Austin Noise has been Retired

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In case it’s not obvious by the long span of time between now and the last time an article was posted here, Austin Noise has been retired. I’ll keep this website up for archival purposes for as long as I feel like paying for the domain name. I’ve moved from Austin and so am not in much of a position to be involved in its community noise issues.

Many thanks to the excellent people I worked with in my adventures. When I started this website, I had no idea that I would meet such interesting people or engage in such interesting projects. I may have gotten into a little trouble here and there, but it was all worth it.

Good luck to you Austinites in resolving your noise issues, and please remember that the person on the other side is a person. In 13 years as an acoustical engineer I’ve run into only a very small handful of people who intentionally tried to get away with doing something unfair. Chances are very good that the person or people who you think are being unreasonable are trying their best to be good neighbors.

Talk to each other!

-Joshua

The Drummer Next Door

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Hi Joshua,

I am a professional touring musician (drummer). I recently purchased a house in Round Rock. I have been sound checking and playing for the last few weeks. All I can find on the laws here online is that between the hours of 7am and 10:30 pm “reasonable noise levels are acceptable” in residential areas. Unfortunately my neighbors felt it necessary to have the police come by last Saturday (at 9pm) which I was repremanded and informed I would be getting a citation if they came back. The noise level measures 10 db at the side walk . It is noticable but sounds like a radio (to me) and I am speculating that it can’t be heard in the other houses. Can you advise me on what specific levels are acceptable in my area and how I can respectfully deal with the local law enforcement if I am with in my legal right? I do not want to upset my neighbors by any means but I need to play and quite frankely if I have to listen to 10 kids, dogs barking all night and the occasional domestic dispute I don’t think I should have to abstain from practice as long as I am legally with in my rights. Thank you for your time. It seems musicians are easy targets for this vague regulation.

The Round Rock noise ordinance has fairly high sound level limits, but the language concerning audibility is otherwise quite strict. The section that applies to you is 14-213.b.8…

Radios, television sets, musical instruments and similar devices.

a. Operating or playing, or allowing the operation or playing of a radio, television, phonograph, musical instrument, or similar device that reproduces or amplifies sound so it creates a noise disturbance for any person other than the operator of the device.

b. Operating or playing any such device so as to cause a noise disturbance.

c. Operating or playing any self-contained, portable, handheld music or sound amplification or reproduction equipment in a public space or public right-of-way so as to cause a noise disturbance.

…which relies on the “noise disturbance” definition in 14-210…

Noise disturbance means any sound which:

(1) Disturbs a reasonable person of normal sensitivities;
(2) Exceeds the sound level limits set forth in this article; or
(3) Is plainly audible as defined in this section.

…which relies on the “plainly audible” definition in the same section…

Plainly audible means any sound or noise from any source that can be clearly heard by a person with normal hearing faculties at a distance of 200 feet or more from the real property line of the source of the sound or noise.

…So it would seem that if your playing isn’t audible 200 feet beyond your property line, you’re in the clear. In reality, I doubt that’s
the case, especially in light of 14.211.b.3…

The official need not determine the particular words or phrases being said or produced, or the name of the song or artist producing the
noise. The detection of a rhythmic bass reverberating type of noise is sufficient to constitute a plainly audible noise.

Just the sound of your kick drum, which is likely to be “detectable” more than 200 feet away, would be enough to put you into the “plainly audible” definition and mean that you are not in your legal right to play at any time of day. It’s very strict, yes, but that’s how it’s written.

About your noise measurement, what do you mean by “10 db”? What type of instrument did you use to measure that, and what were the settings?  The Round Rock ordinance specifies using A-weighted with the “slow” time constant. It’s extremely unlikely that you measured 10 dBA anywhere in your neighborhood, as this is far below typical background noise levels in a residential area.

Sound can transmit through more mediums than just the air. While it may seem like your playing shouldn’t be audible inside another house based on how it sounds outside, it’s very possible that it is actually more audible inside a nearby house than it is outside. I know it
isn’t intuitive, but it happens more often than you think, particularly with drums.

Your kick drum sits on the floor, and your toms and snare are pointed towards the floor and walls. A drum kit is an efficient machine for
injecting vibration energy into the ground through your building structure, particularly if your house has a slab foundation. That
vibration energy can travel quite efficiently through soil to your neighbors’ house, where it radiates from their walls and floors as
audible sound. Inside the house, it wouldn’t be possible to tell whether the sound arriving there is traveling through air or soil or both, but it doesn’t matter because the effect is the same.

Here is my advice:  Forget about sound levels and take full advantage of psycho-acoustics.

Before you do anything else, and this really is important, have a short conversation with your neighbor. Let them know that it’s not your intention to disturb them. See if you can establish a practice schedule with them and promise to always be done at a particular time, and be sure to stick to that schedule. Tell them you’re a professional musician and that practice is an important part of your livelihood.

There is plenty of research that shows a person’s reaction to a sound is affected in a major way by their knowledge of and disposition to
the sound. If they have no sense of when a sound will start or when it will end, and they have no sense that the person making the sound cares about their well-being, the sound will seem especially annoying. However, if a person knows that the noise-maker is concerned about them, and knows when to expect the sound and that it will end at a particular time, the sound seems less annoying, meaning they’re less likely to call the police.

Be friendly, be understanding of their position, don’t be demanding or act like you’re entitled to anything, and you can buy yourself 10 dB
with a single conversation. An offer of a plate of cookies might be worth another 3.

The next thing to do is to get some 2x4s and plywood and build a platform for your drum kit. 12″ high ought to do it. Make feet by standing 2x4s on end. The idea is to minimize the area of contact between the drum platform and your floor, as this will be the pathway
for vibration to get into your building structure and into the soil. It wouldn’t be a bad idea to place some insulation under the platform,
either. You don’t need to stuff it under there, just lay it loose and it will do its job.

When you talk to your neighbor tell them you’re going to build a drum platform designed by an acoustical engineer and that it should reduce the amount of sound reaching their house. Maybe even show them the platform when it’s finished. If they expect the platform to make the sound quieter, it WILL seem quieter, even if sound levels are actually unchanged. We tend to hear what we expect to hear (how else could Monster Cable get away with asking $50 for a 4′ cable?).

And finally, if you have windows in your practice room, cover them up. Build some temporary panels out of 3/4″ plywood that you can place across your windows. They don’t need to be permanent, they just need to do a good job of keeping sound from going out the windows, which is by far how most sound usually leaves a building. Be sure your panel overlaps the edges of the window by at least a few inches. Put some weather-stripping around the edges of the panel so that it forms a nice seal with the wall. Blocking off the windows will probably make a pretty big difference. And of course, be sure to let your neighbor know you’re doing this.

In answer to my response and my question about how he measured sound…

I have an application on my phone which is fairly accurate and it uses the mic input to measure sound waves and turns it into a relative decibel reading. I agree with you about contacting the neighbors, I have not had a chance to meet them yet and tell them about myself and what steps I am taking to prevent noise from leaving the house. Thank you again for the advise. Though to me the noise is low and unoffensive I do not think for a minute that my neighbors right to solitude should be violated. I just want to be able to practice uninterrupted  and definitely with out police involvement.

Thanks so much Joshua!

Those smartphone applications are handy, but they’re not good for measuring anything impulsive or low frequency, as the microphones they put in smartphones just aren’t capable of handling those types of sounds.  Drums are both impulsive and low frequency, so it’s really not a good tool for that type of measurement.  Also, A-weighting (what the ordinance uses) discounts low frequencies very aggressively, so even with a professional sound level meter you wouldn’t be able to make much in the way of meaningful conclusions based on measurements.  In this case I think it’s most pragmatic to abandon technical argument and approach the problem from a public relations and psycho-acoustics angle, which seems to be your game plan.

This works both ways.  If you’re reading this article and you are on the side receiving the noise from a neighbor, it’s worth taking the time to talk to them before you call the police.  Your neighbor may not realize that their activity is disturbing you.  If their first message from you is a visit from the police, it’s likely to put them into a defensive mindset and assume that you are an unreasonable person.  Save the calls to the police until after diplomacy has failed.  A single conversation could solve the issue and put you on good terms with the people you live next to.

The Music Venue Assistance Program and Noise Mitigation Case Study

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Item 14 of February 2nd’s City Council meeting was discussion and approval of a resolution to change the name of the existing Music Venue Relocation Program to the Music Venue Assistance Program, and to provide $40,000 from the Downtown Development Fund for a music venue noise mitigation case study.  The action items in the resolution are worded as follows.

  • The City Manager is directed to change the name of the Downtown Venue Relocation Program to the Music Venue Assistance Program.
  • The City Manager is directed to initiate, fund, and oversee a sound mitigation case study of a relevant music venue in an amount up to $40,000 from the Downtown Development Fund.
  • The City Manager is directed to engage cross-departmental staff to work with the Music Commission to develop recommendations, based in part from the case study, to mitigate sound from music venues and report recommendations to Council on or before July 20, 2012.
  • Subject to Council approval and availability of funds, the City Manager is directed to add the amount of $100,000 per fiscal year to the Downtown Development Fund for the Music Venue Assistance Program until the amount available for the program is $750,000 [or other funding recommendation, pending results from the case study].

The previously existing Music Venue Relocation Program holds  $224,000 that was meant to be available to loan to music venues forced to relocate.  The original intended recipient was Liberty Lunch, but that relocation never panned out.

With the change of the fund’s name, its purpose is converted to making low-interest loan money available to music venues who want to implement noise mitigation measures.  I think this is a very smart move, as resistance to building improvements for noise purposes is naturally due to cost in most cases.

Having access to a lump of cheap money means venues can implement a variety of effective mitigation measurements simultaneously.  The typical, low-cost approach is to consider a variety of mitigation techniques and try them out one by one, often starting with the cheapest.  This means that small, single ideas are implemented without much to show in terms of results.  The best approach is usually to make significant, coordinated changes that are known to be effective, and having money available for this at a discount rate will make this much easier for venues to accomplish.

I’m not as convinced of the value of the case study.  As I understand it, the point is to explore some noise mitigation ideas to show that noise mitigation is possible and to learn a little about what does and doesn’t work.  Such knowledge can be used to start a sort of play back used by the Music Department to offer recommendations to venues seeking advice.

While there is sense in this, it does seem like re-inventing the wheel.  Noise issues like those we experience in Austin are far from unique.  They’re regularly studied and often solved all over the world.   There is a wealth of information available in the form of case studies and other papers in the journals of professional societies such as the Institute of Noise Control Engineering (INCE) and the Acoustical Society of America (ASA).

One has to wonder why the city doesn’t spend the money retaining one or more acoustical engineering firms to provide this kind of information.  $40,000 can buy a substantial amount of time from a noise control expert; certainly more than enough to commission the writing of a set of guidelines for improving noise isolation of music venues.

Perhaps the underlying purpose of the case study is to show Austin that co-existence of music venues and residences can be improved through the use of effective noise control that doesn’t diminish the live music experience.  This I can understand, as I’ve often found that the very concept of acoustical engineering as a field distinct from “sound engineers” is unknown among those involved in the Downtown Austin discussion.  A clear example of what can be done set in an environment people are familiar with could do quite a bit to raise awareness of the potential benefits of good planning for noise reduction.  I can see the value in that approach.

In order to maximize the opportunity, a venue will need to be chosen that suffers from a range of problems.  Since each venue has a particular set of characteristics, it seems unlikely that studying a single location would yield $40,000 worth of information.  Maybe the study would produce better results if multiple venues were considered.

Whether or not an acoustical engineering firm is part of the case study, I implore the Music Department to take good, meaningful before and after sound level measurements (or, better yet, have measurements taken by a knowledgeable professional).  This case study will be a great opportunity to put some real numbers to the noise the venue produces before and after.  Limiting measurements to simple, police style A-weighted levels at the property line would be an unfortunate loss of some very valuable information.

1/3-Octave values should be taken in Leq and Ln (statistical values), and measurements should be made at a number of key locations that will allow the true noise reduction to be described.  Measurement positions should include multiple locations inside the venue, including at the mixer and at enough spots in the audience to make a valid determination of whether the music is “loud enough” for the crowd.  Outside the venue measurements must be taken at the nearest residences, so that the actual noise impact can be described.  Of course property line measurements will be taken, but their only real value is in comparison to our curious source-oriented noise ordinance.

The W’s Unpopular Windows

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The windows at the W Hotel and Block 21 Residences above have been in the news quite a bit lately.  In the below video, KXAN’s Jarrod Wise gives a good overview of the situation.  It also summarizes a 3rd party study (referred to hereafter as “the consultant”) concerning the Block 21 Residences and Cedar St. Courtyard that was recently released by the City.

In this article I will expand on these 3 points from the port covered by Mr. Wise in the video:

  • Cedar Street Code Compliant
  • COA Measurements Questionable
  • W Residences Not Built to Reasonable Sound Standards

Caveat emptor:  In the report are many measured sound levels referred to as “dB.”  Frustratingly, the consultant never specifies what frequency weightings or time constants were used for the measurements.  It seems reasonable to assume he had his meter set to A-weighted SPL with the “slow” time constant to match the noise ordinance, but I can’t know that.  Reading and recording an instantaneous sound pressure level (SPL) with sound level meter during this type of measurement requires the user to make judgments about what sound level to record, as the actual measured level changes frequently in time, especially with music as the noise source.  Without having observed the measurements myself, I am unable to know what type of methodology the consultant used to interpret the meter’s display, nor can I know how consistent he was measurement to measurement.  My assumption is that he attempted to choose representative values that would be comparable to a time-averaged Leq measurement.  If this assumption is incorrect, some of the conclusions drawn below in the Construction Quality discussion will be less accurate.

Is Cedar Street code compliant?

Mr.  Wise’s news story concludes that Cedar St operated according to code, as measured by the consultant.  This is not strictly true.  The report concludes that “Cedar Street stayed within compliance virtually all the time” and indicates that occasionally they measured levels exceeding “85 dB” (presumably 85 dBA) at the property line.  The noise ordinance makes no allowance for any kind of time averaging or momentary spikes in noise level.  85 dBA (slow) is an instantaneous value, and if the sound level exceeds that value for any period of time, even a few milliseconds, they are not in compliance with the ordinance as it is written.

The City’s Noise Measurements Are Questionable

I won’t spend much time on this topic because any regular reader of this site already knows I agree with this fully.  The report raises the issue that A-weighted broadband level is a poor choice for measuring music, and that is absolutely true.  The nature and frequency signature of live music is simply not compatible with simple A-weighting in all situations.  The report suggests using C-weighting instead of or in addition to A-weighting, which I agree with.  It also suggests using time averaging.  Assuming the author is referring to Leq, I agree with this as well, as it would make measurements far more objective and would eliminate the problem of deciding whether occasional spikes should constitute an ordinance violation (see above).

Note that these objections aren’t really about how the city measures sound, but actually how the noise ordinance specifies that sound should be measured.  On the topic of how measurements are conducted, there are further problems that need repair.  I am unaware of what type of meter the Music Office uses, or how they operate it, but I do know that APD uses B&K 2240 meters, which don’t support the slow time constant.  In other words, with that meter, APD is literally incapable of conducting sound level measurements as specified by the noise ordinance.

W Residences Construction of Dubious Quality

To me, this was the most interesting part of the report, and the part I will spend the most effort on.  The consultant took some basic but meaningful measurements at several residences with windows open and windows closed.  With windows closed (standing next to a window), levels of 55-62 dB (again, presumably dBA) were recorded, and in the same position with the windows open, they recorded levels of 68-73 dB.  Comparing these measurements results in a rough approximation of an A-weighted outdoor to indoor noise reduction of 11-13 dBA.

Simply put, this level of performance is terrible for any type of residence.  As a point of reference, HUD expects that basic residential building shells should provide noise reduction of 20 dBA.  HUD projects are meant to provide low-income housing and are generally not high-end buildings.  It is reasonable to expect exterior partitions of luxury condominiums to significantly exceed 20 dBA noise reduction, particularly when they are placed in a downtown area close to outdoor music venues.  If the reported measurements are accurate, the level of sound insulation provided by these residences is far below what is expected at their price range.

Poor acoustical performance can be attributed to poor design or poor construction, or both.  In the case of Block 21, it appears to be both.

The consultant observed “outside air moving through parts of the windows, doors and mullion assemblies in each of the apartments visited.”  Properly sealed windows and mullions are vital to controlling noise transmission.  Air leaks in windows large enough to allow outside air to be felt permeating the window certainly can explain noise reduction of less than 15 dBA.  In fact, 15 dBA is the expected noise reduction value of a partially open window in the World Health Organization’s Guidelines for Community Noise.  Those observations, along with the falling glass problem, seem to indicate major shortcomings in the quality of glass installation.

Suppose the construction quality was up to standards, would the design of the building envelope provide adequate noise isolation?  To attempt to answer this question, I performed a fairly standard outdoor to indoor noise analysis based on the following information.

  • The floor plan of a W Residence unit on the Northeast corner of the building (facing the Cedar Street Courtyard), available on the W’s website.
  • A spectrum for live music sound measured by me on the balcony of a downtown Austin residence.
  • The “windows open” sound levels from the report
  • Supposed STC values for exterior windows discovered by the consultant on an architectural drawing
The floor plan I used for the room dimensions in my analysis is shown below, with some significant acoustical features in text that I added.
The important features to consider are:
  • The area of the windows.  Larger windows are exposed to more exterior sound energy.
  • The size and sound absorption of the room being analyzed.  Hard surfaces, such as windows and wood floors, cause sound to bounce around a room more than soft surfaces.  This leads to higher interior noise levels.
  • The expected use of the room.  People are expected to be sleeping in bedrooms, so more stringent criteria should be applied there than to rooms more likely to be occupied in the day.

Almost half of all the partitions surrounding the living/dining/kitchen area floor to ceiling exterior windows.  This is a challenging situation acoustically.  High performing (read: expensive) windows are required to properly isolate interior spaces from downtown noise.  According to a detail the consultant saw on an architectural drawing, the exterior windows used on this building are STC 35 (he was unable to verify that STC 35 windows were installed).  STC 35 windows are on the expensive side of the cost spectrum, but not quite “high end.”

For my analysis I used typical transmission loss values for large area STC 35 windows taken from a collection of STC test data.

An exterior noise spectrum based on measurements I did earlier this year in downtown Austin.  The location of these measurements was on an exterior balcony with a partial view of several music venues.  The two situations are similar enough for this analysis.  I adjusted the spectrum to 71 dBA, which is the center of the range reported by the consultant for his open window measurements.  In reality, an open window will provide at least a few dB of noise attenuation, so 71 is a pretty conservative number to use here.

Based on the above information, the calculated interior noise level for the Living/Kitchen/Dining room is 48 dBA.  Compared to the WHO suggested criterion for indoor levels of 35 dBA Leq, this is quite loud.  Also consider that low frequency sound typically found in live music is mostly unaccounted for in A-weighting.  Music noise transmitting into this room through the windows is likely to be quite bothersome to occupants, even with no construction defects.  (Remember that I am assuming the SPL measurements taken by the consultant are comparable to Leq).The Master Bedroom is a little more absorptive (carpet instead of wood floor) and has a smaller total window area than the living room.  However, it is smaller in volume and should have more stringent noise criteria, as sleep disturbance becomes the primary concern.

The calculation predicts a level of 45 dBA in the master bedroom.  This is well above the 30 dBA Leq suggested by the WHO for sleeping areas.  It is equivalent in magnitude to the 45 dBA Lmax suggested as a limit for impulsive, maximum levels using the “fast” time constant.  With a varying noise source, “fast” measurements will always be greater than “slow” measurements.  Therefore both the Leq and Lmax aspects of the WHO’s suggested criteria are predicted to be exceeded.  Remember, again, that low frequency sound typical to live music is not well accounted for in A-weighted levels, meaning the intrusive noise is likely to be even more disturbing.

According to these calculations, the exterior partition design and window selection of the Block 21 residences appear to be in appropriate from an acoustics standpoint.

Additionally, the report mentions several instances of wall insets that essentially reduce the exterior partition at those locations to a single layer.  The consultant claimed that noise could clearly be heard coming through these areas.  Another apparent design flaw.

An acoustical analysis should have been performed during the design phase to catch these types of problems.  Units costing half a million to several million dollars and located in a downtown area known to have significant noise from music should provide a high degree of acoustical isolation (for a residential structure).  According to the information in the report, the Block 21 Residences fall quite short of those standards, in terms of both design and construction.

It’s actually very possible that an acoustical analysis was performed.  Recommendations from acoustical consultants are typically some of the first on the “value engineering” chopping block.  The VE phase is when the architect and the developer review the nearly complete building design to determine what features can be removed in the name of cost savings.  Design elements meant to reduce noise exposure are frequently cut out, presumably because their value is more difficult to conceptualize.  Acoustical retrofits are very expensive.  So are lawsuits, which it seems reasonable to predict will occur.  If proper acoustical design was VE’d out of the W project, it is a gamble that does not seem likely to pay off.

In closing, please remember that many of the values discussed in this article are not known absolutely.  I’ve done my best to clearly identify where assumptions needed to be made, and to be as reasonable as I could in making them.

The Halfway Point Between Developers and Venues

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Tonight I watched the Austin Music Commission hold their regular monthly meeting, conveniently broadcast live over the internet.  When the video is ready, you can see it on Channel 6.  One of the items on their agenda was to discuss the “cultural impact of noise in [the] downtown area.”

All of the members in attendance thought it made sense for the City to encourage, or possibly even require, the use of higher performing windows (“thicker windows,” they called them) in downtown buildings that were expected to be exposed to downtown noise, particularly related to music venues.  I think this is a good idea (with some qualifiers, read on).

When searching for ways to express their idea in material terms, they got as far as saying that mitigation (“thicker” windows) should be based on the allowable noise of surrounding venues according to the noise ordinance.  In most cities, this would be a perfectly sensible thing to say.  The problem is Austin’s ordinance is source-oriented rather than receiver-oriented.  If you have ever spoken to me about Austin’s ordinance, or read any of my earlier articles, you know that this is my number one complaint about our noise ordinance, and something that sets us apart from most other cities.

The commission was also looking for ideas on ways the venues could meet half-way with the developers.  They noted that Don Pitts and the Music Office work regularly with venue owners to lessen noise impacts.  By every report, Mr. Pitts does a great a job in communicating with venues and works very hard on finding reasonable solutions, but relying on the Music office is itself not an objective determination of where venues should meet developers, of what the half-way point is.

It turns out it’s very easy to define a half-way point in terms that are completely objective and simple to explain.  A half-way point can be defined as a maximum sound level a venue is allowed to cause at a nearby property.

The first step is to rearrange Austin’s noise ordinance with receiver-oriented sound level limits (or to change the permitting system to use receiver-based venue specific levels).  Under the current system, a producer of noise is required to maintain a certain sound level at their own property line (source-oriented).  This treats all venues as if they’re the same distance from their neighbors.  A source-oriented system provides no reward to venue owners who make sensible decisions about their venue’s location, or orientation, or any sound mitigating features they may install to protect their neighbors from excessive noise.  Likewise, the source-oriented system is no more restrictive on venues that are set up poorly with respect to noise control.  There’s no legal incentive to try to be a good neighbor.

A receiver-oriented noise ordinance specifies the sound level limits you are allowed to create as measured at your neighbor’s property, and according to the type of neighbor you have (i.e residential, commercial, and industrial, where residential would have the most restrictive limits).  This system implicitly rewards venue owners who choose their locations carefully and arrange their venues in ways that are conscious about their neighbor’s noise exposure.  Noise mitigation measures such as orienting a stage away from a residential building or constructing a noise wall result in effectively higher permitted sound levels inside the venue.  This means the person operating the mixer has greater freedom to turn things up if the performance demands it.

On the developer’s side of the equation, the half-way point (in the form of a sound level limit) provides a reference point for buildings to be designed with respect to noise.  Knowing what the maximum expected outdoor sound levels are, an architect (or the architect’s acoustical sub-consultant) can specify the appropriate walls, windows, and doors to meet an acceptable indoor noise level.  The acceptable indoor level can be set by building code.

Some cities attempt to over-simplify this process by defining a one-size-fits-all minimum window STC.  This is a mistake.  Interior sound levels due to sound energy transmission through a window depend on the size of the window, the size of the room, and the furnishings inside the room (how absorptive or echoic the room is).  Very large windows in rooms with all hard surfaces require higher STC values than small windows in plush rooms to achieve the same indoor sound levels.

Implementing these requirements would create a reward system for developers.  When developers are willing to do the work to find sensible building designs, they are rewarded with less expensive ways of protecting the residents of their buildings from noise.  The noise arriving at their windows will be a known quantity, so appropriate building elements can be chosen in the design phase.  This is much less expensive than lawsuits and retrofits.

Declaring a half-way point in the form of a receiver-oriented noise ordinance that is written with thought and research while requiring developers to meet a maximum interior noise level is the most elegant and fair way to encourage both developers and venue owners to respect one another while providing a framework where everyone can prosper.  Both sides can proceed confidently, knowing there’s an objective measure to show that they’re doing their part.

Appropriate sound level limits (both indoor and outdoor) can be established based on consideration of relevant factors, including:

  • Sleep disturbance research
  • Construction costs research
  • A survey of existing sound levels, including consideration of contributing venues
  • Comparison to successful noise ordinances from other cities
  • Importance of live music in the city’s identity
  • Research into sound levels typical Austin residents are willing to endure, as compared to other cities

Building an apartment with huge windows downtown might provide for outstanding views that people are willing to pay a lot of money for, but it’s absolutely not sensible for anyone to expect such an apartment to be quiet at night, unless they’re willing to pay a lot of money for high-STC windows.  It’s unfair to expect downtown music venues to turn things down to accommodate such poor design.

Similarly, no sensible person would believe that setting up a roof-top bar with no sound containment across the street from an apartment building will not cause residents of that building to lose sleep.  It’s especially distasteful when these types of actions are defended by declaring any complainers haters of live music.  This is also unfair.

I think the Music Commission is absolutely on the right track with the discussion they had this evening.  I hope to see their ideas fleshed out into thoughtful and meaningful changes in the way our city considers noise.

The Nutty Brown Cafe – Review of Analysis and Mitigation

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In November of 2009, I set up a sound level meter near a home in the vicinity of the Nutty Brown Cafe (NBC) in Dripping Springs to take measurements during a show.  I did this in response to the public discussion about some of the Nutty Brown’s neighbors being upset by music from the amphitheater.  Like many community noise topics, this discussion was becoming very emotional with increasingly negative and personal things being said by supporters of both sides, but with little to no technical facts as a basis.  I summarized my measurements and compared them to a handful of meaningful criteria in a post on Austin Noise. The measurements I took showed, pretty clearly that, in that location, sound from the Nutty Brown could be considered loud and disturbing.  Conversations followed my article on various websites, including this one, and at one point I mentioned that, due to the amount of high frequency noise escaping the venue, there may actually be some things that could be done to reduce the noise impact of the venue on the neighborhood.

A few months later I heard from Mike Farr, the owner and operator of the Nutty Brown Cafe.  He offered to bring me on as a consultant to help find ways of reducing the amount of sound reaching neighbors from the amphitheater.  Here was a chance to actually work on the problem directly, instead of just talk about it on a website.  I gladly accepted but included the condition that, when all was said and done, I would be able to write about my experience on Austin Noise.  Here is that article.  Make sure you have some time, because this is a long one.

The first step was to meet with Mr. Far and Mr. Smith, the contractor in charge of configuring and operating the sound equipment at the amphitheater.  I learned that community noise had been a concern since the time the stage had been erected, and that they had tried various techniques at containing sound.  They had chosen flown arrays over stage-sitting stacks of speakers for their ability to be pointed down, and they had tried alternate scrims to cover the speakers in hopes of achieving better diffusion or otherwise alter the propagation path of sound from the arrays.  They had also tried some other measures that I don’t recall the specifics of.  Some of their attempts had yielded success, but without objective measurements at receiving locations, they relied mostly on response from the community for feedback (still a valid source of information).

Probably the most dependable technique they employed was to watch property line noise levels closely, with measurements at regular intervals.  Originally they attempted to keep property levels at 80 dBA or less.  Currently they strive for 75 dBA.

After a few meetings, I devised a plan and Mr. Farr approved it.  The first step was to attempt to establish where the music was bothersome geographically.  I published a survey on this website that asked people living within a few miles of the cafe to report where they lived, whether music from the cafe was bothersome to them and, if so, what qualities of the music was bothersome.  About 20 people responded with usable information, which was enough to give a general sense of where people were being disturbed.

In internet conversations the residents of Belterra were frequently blamed for being unreasonable complainers.  Belterra residents were cast into a role of being newcomers who bought a house near the Nutty Brown and then proceeded to complain about it.  I had my doubts about this, as the geography didn’t really match that scenario.  The survey (and the later filing of a TABC complaint by a group of homeowners) confirmed my suspicions.  I received more pro-NBC responses from Belterra than any other neighborhood, and all but one of the complainants lived in old neighborhoods to the northwest.

The first survey question was simply “can you hear music from the Nutty Brown?”  The responses are shown below.  Each circle is the location of someone answering the survey.  A green circle means they can’t hear the music at all (there are more of these outside the frame of this image).  A yellow circle means they can hear the music but aren’t bothered by it (some of the people from Belterra answered that they like that they can hear it).  A red circle means they find the sound bothersome.

The stage faces WNW.

The survey had a fairly predictable outcome. People bothered by the music are either close to the venue or in the “line of fire” of its speakers.

The next two questions dealt with the audible qualities of the sound.  I asked people to consider high frequency noise (cymbals, vocals, guitars) and low frequency noise (kick drum, bass guitar) separately.  A green circle means the sound is inaudible.  A yellow circle means it’s audible outdoors but not indoors.  An orange circle means it’s audible indoors.  A red circle means it’s clearly audible indoors.

Here is the high frequency audibility map.

And here is the low frequency audibility map.

The results are, again, somewhat predictable.  Low frequency has better carry and is better able to penetrate building shells.  What was surprising was how far away high frequency noise can be heard, even indoors.  This suggests that special ground and atmospheric effects are at work to carry the sound further than it would be able to carry over a plain, flat surface.

To attempt to find a link between the geography of the area and the locations of houses where the sound is audible, I constructed a computer model of the area using SoundPLAN acoustic modeling software.  I built the model using elevation data from the USGS, and built a “stage” at the location of the Nutty Brown with a couple of simple noise sources to represent the arrays and subwoofers.  When I superimposed the approximate locations of survey respondents things became more interesting.

SoundPLAN does not consider unusual atmospheric effects, but it does consider the effects of roads and valleys.  Based on ground shape alone, it looks as though people who can hear the music tend to live in locations that receive more sound energy than others.  if you follow the contours away from the stage towards the northwest, you can see that the noise drops off from red to green, but then picks up again, all the way back to orange in some places.  Due to the specific changes in elevation, noise is able to reach these “hot spots” more efficiently than if it were just traveling over perfectly flat land.

In this figure the yellow, red, and green circles are the results of the “can you hear” survey, and the white circles are the approximate locations of some of the protestants against NBC’s liquor license.  Notice that the red and white circles almost all land on a hot spot (or the leading edge of one).  I will come back to this concept later in the article.

This is important because it helps to explain the sharp divisions between people living in the area between those who are bothered by the sound and those who are not.  Due to the complicated geography of the area, it’s possible for people living only a few hundred feet from each other to have very different experiences.  To some, the sound may be barely audible, or even inaudible, while to their neighbors the sound may be clearly audible.  This is not an intuitive situation, and it’s easy to imagine people who receive little sound energy considering those who complain about the sound to be unreasonable or overly sensitive.

At this point it was clear that there would be no easy answers.

Continue reading ‘The Nutty Brown Cafe – Review of Analysis and Mitigation’ »

Austin Formula 1 Track Noise Analysis

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With construction on the new Circuit of the Americas track underway in Southeast Austin after a quick approval process, some are uncertain about what benefits and detriments the track will have for the city in the long run.  Unable to find evidence of any kind of environmental or noise study, I decided to build a computer noise model of the track and the surrounding areas using SoundPLAN to investigate the potential noise exposure of the surrounding area caused by vehicles operating on the track.

These are the data and assumptions that went into the model:

  • Terrain data and image data for the area came from the National Map.  Construction of the track will result in elevation changes in certain places, especially along the track itself, but I don’t have access to that data so I had to assume the elevations would be close to existing conditions.  Long-distance propagation like this should not be highly affected by the types of elevation changes that the track area will undergo.
  • Track layout and facility building locations were taken from the posted Conceptual Master Plan at the Circuit of the Americas website.
  • The noise source was assumed to be a single open-wheel car circling the track alone.  I was unable to locate noise data for a Formula 1 vehicle, but measurement data for an IndyCar pass-by was presented by Harris, Miller, Miller & Hanson in their analysis of the Baltimore Formula 1 track.  Formula 1 and IndyCar vehicles are indeed different, but should be similar enough for the purposes of this study.  If anything, this is a conservative substitution as Formula 1 vehicles operate at more extreme parameters.
  • Facility Buildings that could provide some noise shielding, including the grandstands and maintenance buildings, were included in the model.
  • Natural Seating Areas around the track were modeled as grassy berms to provide noise shielding where they are located.

The noise model predicted the maximum level experienced based on a single trip around the track for one car.  Multiple cars in a group would, of course, be additive and would increase the predicted levels based on the number of cars according to logarithmic addition.  2 cars would be ~3 dB louder than one car, 3 cars would be ~5 dB louder than 1 car, 4 cars would be ~ 6 dB louder than one car, 5 cars would be ~7 dB louder than one car, and so on.

The results for the entire analysis area are shown below:

CotA Single Car Pass

To the West, there appear to be no real problems.  Out in the country the car on the track would be clearly audible outdoors, but probably not disturbing.  To the North, South, and East, the track is much closer to the property line and to residences.  A single car would register levels as high as the upper 80’s dBA for the closest residences, which most people would find disturbing, both indoors and outdoors.

Scanning the satellite images, I located what appear most likely to be residential structures close to the track and included them as buildings in the model.  They are shown as dark blue boxes in the figures.

On the north side of the track, the houses near the entrance can expect noise exposure from a single vehicle pass-by ranging from about 70 dBA to 80 dBA.  This would be difficult to talk over in an outdoor environment, and would be clearly audible inside of most homes (though not necessarily disturbing).  Multiple cars on the track would likely increase interior sound exposure to levels that most people would find annoying.

CotA Single Car Pass Zoomed North

To the East, the track is closer to residential buildings, so greater impacts are expected.  Noise exposure between the mid 70’s and mid 80’s dBA from a single car pass is predicted for homes in this area.  Assuming a difference of about 20 dBA outside to inside (typical for residential buildings), inside noise levels could be expected between 55 and 65 dBA for a single car.  These levels correlate to loud but normal conversation volumes, meaning that people inside these houses would need to either speak loudly or wait for a car to pass to carry on a conversation.

CotA Single Car Pass Zoomed East

Predicted noise exposure on the south side is greater still, with some buildings expected to be exposed to levels in the mid to upper 80’s dBA for a single vehicle pass.  With these exterior noise levels, it may be difficult to carry on a conversation inside of any building with ordinary construction.

CotA Single Car Pass Zoomed South

There are still other potential noise impacts to consider beyond just the sound from a single car on the track affecting residences in the area.

  • Other noise sources, such as traffic and the cheering of spectators may produce noise sufficient to disturb residents of the area.
  • Race car noise may stress or frighten livestock.
  • Noise signatures from other types of cars using the track, such as the V8 Supercars, may have lower frequency content, resulting in noise with longer carry and better ability to penetrate building structures.
  • It appears very likely that the track will be operating in exceedance of the Austin noise ordinance.
If noise problems are identified and addressed early in the design process, they can be solved before any impacts occur, during the original construction.  In most cases, it is several times more expensive to solve a noise problem through retrofit than to include mitigation in construction.  Additionally, once a noise impact on a community has already occurred, it is substantially more difficult to achieve satisfaction with the surrounding community than it would have been had the impact been avoided at the outset.
Based on the results of this analysis, and the potential for other noise impacts associated with the race track facility, a comprehensive noise analysis as part of the track’s design and construction seems like a prudent investment.  An analysis performed by an acoustical engineer could determine the necessary locations and heights of barriers and berms that would mitigate the noise impacts on nearby residences.

Questions for Place 4 City Council Candidates on the Austin Noise Ordinance

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The Austin Noise Ordinance, particularly as it relates to live music,
is a topic of discussion in the Place 4 City Council race. Running
for this position are Toby Ryan, Eric Rangel, and the incumbent, Laura
Morrison. I am offering this website as a venue to discuss the noise
ordinance in as much detail as they like. I’ve asked all three
candidates the following questions and promised to copy their
responses word for word.

Question 1 – What do you like about the noise ordinance as it
currently stands, and why?

Question 2 – What do you dislike about the noise ordinance as it
currently stands, and why?

Question 3 – Suppose you are given a blank piece of paper and asked to
write a brand new Austin Noise Ordinance. How would you write an
ordinance that is fair to residents and venues while preserving the
characteristics that you see as being important to Austin’s identity?

Here’s how Laura Morrison responded:

Question 1 – What do you like about the noise ordinance as it currently stands, and why?

In 2009, I supported and cosponsored the recommendations of the Live Music Taskforce
addressing outdoor live music venue sound permits, marking a significant union between
neighborhood activists and the music community to find common ground and work
towards solutions.

The compromises reached in the new ordinance are by no means perfect, but they
include several improvements to the city’s outdated permitting process, such as including
consideration of what land use existed first. If a new residential condo tower is being
built next to an existing live music venue, the developers of the tower need to focus
on soundproofing for their tenants. Likewise, if a new venue is being built next to
an existing residence, the venue needs to work with the neighbor so the two uses can
reasonably coexist.

Within the new process, there is more opportunity for a conversation between the venue
owners and the adjacent residents. I supported the creation of the Music Department,
which was transformed into the Music Office. There, we have three staff members,
including an experienced sound engineer, working to help address concerns, with
recommendations that can strike a balance to allow the venues to play music with
minimal disturbance to adjacent residents.

The success in resolving conflicts has been outstanding, including venues along South
Congress, Lamar Boulevard and Barton Springs Road.

Question 2 – What do you dislike about the noise ordinance as it currently stands, and
why?

The current permitting process has additional room for improvement, and we are
continuing to adjust it. We have found that the previous permitting process was rigid
and inflexible, as it assumed a “one size fits all” for music venues. We are working on
new options for music venues, including a multi-day permit that allows venues to host
festivals or do weekly series. During this year’s SxSW, the city saw a 20% increase in
venues using the multi-day option, which avoids the need of temporary venues to get
year-round permits.

Additionally, as I mentioned briefly in the first question, I believe our development
regulations need to be strengthened for soundproofing of residents being built near
existing music venues. This is especially important in the downtown area, where new
condos and apartments are being built around established entertainment districts.

Also, now that we have a Music Office to help resolve conflicts between venue
owners and adjacent residents, I believe the ordinance should be more focused on the
development of a sound impact plan. Earlier this year, I cosponsored changes to make
the sound impact plan a formal process for permitting. The way noise travels is unique
for every location, and the focus on decibel limits is incomprehensive. If we can do a
better job at containing noise or redirecting it, we can avoid unnecessary conflicts and
regulations.

Question 3 – Suppose you are given a blank piece of paper and asked to write a brand
new Austin Noise Ordinance. How would you write an ordinance that is fair to residents
and venues while preserving the characteristics that you see as being important to
Austin’s identity?

The key to writing a new noise ordinance is engaging stakeholders on all sides of the
issue to work together to find a balance. It is my fundamental belief that the more
perspectives we have reviewing a proposal, the better results we will have for our
community.

Over the past 3 years, I have worked diligently, collaborated, and had success in bringing
the neighborhoods and music industry together at the table to arrive at consensus
approaches that have really helped to make progress in finding the balance. There may
be people on both sides that would prefer to take hard lines and continue to fight, but that
gets us nowhere. We can only move forward by working together. Austin must remain
the Live Music Capital of the World.

Toby Ryan did not respond.

Eric Rangel did not respond.

Venue Specific Outdoor Music Permits: How To Make Them Work

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In my September 2009 article Certifying Outdoor Live Music Venues, I suggested that, rather than creating an acoustics training and certification program for sound engineers as the Live Music Task Force suggested, it would make more sense to certify the venues themselves.  The subject has come up in recent conversations so I went ahead and fleshed out the idea to a fully developed system for analyzing and certifying venues.  The slideshow presentation below explains my proposal for a system where issuance of outdoor music venue permits are contingent on a noise impact analysis being performed on the venue.

The impact analysis considers potential impacts to nearby residences and, based on a relatively simple and repeatable analysis method, determines sound level limits specific to that venue.  The sound level limits for each venue will be specified in multiple locations, including at the mixer, and will be back-calculated from the maximum allowable residential noise impact.  The presentation goes far more detail and discusses my reasoning for the idea.  It might be a bit of a thick read, but there is a step-by-step example with pictures that starts on slide 15.

What I want people to take away from this, more than anything, is the idea that basing the conditions of a music venues permit on its actual residential noise impact implicitly encourages owners to locate and build music venues with noise as an initial consideration.  Currently in Austin there are too few venue owners who are concerned about the noise impacts they create and are willing to take steps to be better neighbors.  Under the current system there is little incentive to operate this way outside of accumulating karma and receiving fewer angry phone calls.  Under the system I am proposing, venues that are located, built, and organized in ways that reduce noise impacts will reap tangible benefits in the form of higher sound level limits at the mixer. Being a better neighbor is automatically incentivized.

When reading through the presentation, don’t put any weight on the specific sound levels that are used as examples. They’re just examples. The important idea is using a procedure that is objective, fair, and repeatable from venue to venue. When a procedure like this is implemented by the City, the specific sound level criteria can be later decided based on a careful study.

SXSW 2011 Sound Permits Posted

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The list of sound permit holders for this year’s SXSW week are posted on the PACE website.  You can find information about the locations, the dates, the start times and cut-off times, as well as the “decibel limits” set for each venue (either 70 or 85).  Here is the complete list on one pdf.

These follow the new rules for permits that were added in another emergency change to the ordinance in February.