SPL metering, logging, alarm

D

Daniel Postilnik

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Jan 14, 2011
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San Francisco, CA
Hi guys,

I know there is a section of this forum for measurement, and this post involves that partially, but it's really a product query.

In the fitness industry the fact of the matter is that a certain SPL is necessary to maintain the energy level in a room during certain kinds of classes. However, you can avoid damaging the hearing of customers and instructors.

I'm looking for a product that will be able to indicate to someone leading a fitness class if they are operating in a safe range, which could otherwise be difficult to tell if they have been exposed to higher SPL for a while. They It would also be good to be able to collect historical SPL data, such as how loud it gets over the course of a class.

I'm not interested in dosimeters because nobody is being exposed to loud music for 8 hours at a time. However, if people are exposed to 105dbA for 45 minutes from speakers that are 6-8 feet away, I still consider that to be dangerous (it certainly hurts my ears and I'm 26). I found one product that could notify fitness instructors if they're over a certain level:
SL130G - Sound Level Alert with Alarm

However, this can't log data, though there are a number of products that can. Do any of know of a product that has an alarm function and can log SPL data?

Thanks!
 
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Re: SPL metering, logging, alarm

Bennett Prescott said:
Yes, here's a hardware version: AcoPacific - SLARM(TM) Sound Level Alarm, ACOustAlarm(TM) and ACOustAlert(TM) Noise Alert Systems

There may be a great software solution on the way. In general real SPL logging tools are pretty pricey, a better solution might be to add subwoofers so you can get that "energy" without turning up to 105dBA OH MY GOD WHAT ARE THEY DOING IN THESE DANCE STUDIOS THAT IS CRAZY SPL!
Click to expand...
Bennett, I hope your reaction to those levels is not sarcastic. Our audio provider doesn't have an issue with building systems that produce such levels in a small enclosed space, just because a couple of deaf instructors require it.

Unfortunately subwoofers are the main culprit for acoustic penetrations, so they often get turned down first or even turned off at spaces that have particularly sensitive neighbors. This is NYC, and there are always neighbors...

Meanwhile, it actually occurred to me that an SPL meter that can report data wirelessly would be really great to have. Our company can almost definitely afford it.
 
Re: SPL metering, logging, alarm

Daniel Postilnik said:
I work at a company that runs a number of fitness studios for a particular type of exercise activity. Since I started working I have noticed an increasing pattern of complaints both from new instructors as well as customers that the sound systems in our studios are painfully loud. Instructors who have been with the company for a while are usually the cause for these complaints - they have big egos and their hearing is damaged.
Thanks!
Click to expand...

It is definitely an interesting conundrum.. I have installed nearly identical systems in different locations and come back to find some with either blown speakers (where there are no limiters) or complaints of not enough volume, and some with the amps turned back to half and still not tickling the limiters that I had set in DSP before I left...

it all comes down to management.. if they care about hitting a certain Db target, then you need a meter, or at least a measurement and some limiting to stay close to that measurement. In my experience anyone who has a Db number in mind is usually VERY surprised at how quiet the music is when we keep it to that actual number.. often they decide to ignore the threshold.

if you don't have subs, add them. I know they cut through walls, but I still think they add enough to the experience to help avoid excess volume.
Otherwise, you have to ask those in charge, is it really too loud for the participants? or do you need to arrange your space so that those who want it quieter can move to the back?
ps: a well designed system will have even sound throughout the listening space, so this might require adjusting things so that the volume is not as even as it should be...

Jason
 
Re: SPL metering, logging, alarm

Daniel Postilnik said:
Unfortunately subwoofers are the main culprit for acoustic penetrations, so they often get turned down first or even turned off at spaces that have particularly sensitive neighbors. This is NYC, and there are always neighbors...
Click to expand...

There is a "platform" version of a buttkicker designed for bass players. I'm not sure what it's called but it might be worth researching. It'll still produce LF energy, but maybe you wouldn't need as much with them standing (dancing) on top of it.

It might look a bit like one of those dance machine simulators at arcades. Not sure if this is good or bad. :D~:-D~:grin:

Chris
 
Re: SPL metering, logging, alarm

Chris Nixon said:
There is a "platform" version of a buttkicker designed for bass players. I'm not sure what it's called but it might be worth researching. It'll still produce LF energy, but maybe you wouldn't need as much with them standing (dancing) on top of it.

It might look a bit like one of those dance machine simulators at arcades. Not sure if this is good or bad. :D~:-D~:grin:

Chris
Click to expand...
They're on stationary bikes.
 
Re: SPL metering, logging, alarm

The science of hearing protection has been pretty well worked out, if not widely accepted by the entertainment industry. OSHA has formulas for how much SPL can be tolerated without substantially increasing risk of hearing loss, legally enforceable but likely not fully protective. NIOSH has more conservative recommendations, supported by more and better science, but not accepted by industry in the regulatory standard negotiations. dBA is used because it is currently believed that higher frequencies do more damage to hearing than lower frequencies, given similar dB SPL. NIOSH has summarized the science here:
http://www.cdc.gov/niosh/docs/98-126/pdfs/98-126.pdf

While both these systems of recommendations were developed for workplace settings, they do not assume 8 hours of exposure and the formulas are flexible enough to incorporate much shorter periods of exposure to louder levels. All of those recommendations can actually incorporate both occupational and personal/recreational exposures to loud sound. For example, an hour and a half long dance class with SPL of 92 dBA slow at the ear of the dancer "uses up" the entire NIOSH noise dose quota for the entire day, ie assuming that person has zero additional exposure to loud noise over 85 dBA that day. Average SPL above that will increase risk of hearing loss, statistically across the population. People concerned about hearing loss should also pay attention to additional clues such as ringing in the ears or temporary mild hearing loss for hours or days after the exposure, and periodic hearing tests by a competent audiologist are recommended for all people who are exposed to loud sound near these levels. While there is certainly individual variabliity in who gets hearing loss and who doesn't, and we all know people who have great hearing and have been exposed to more than their fair share of loud sound, we do not have adequate science to predict who will and who won't get serious hearing loss later in life. Hearing loss is generally irreversible so once it happens, it is too late, so trying to follow the NIOSH recommendations seems prudent.

That said, I believe SPL is not the only important factor in this discussion. Having played congas for over 40 years on and off for dance classes in dance studios, mostly in NYC, I believe much of the problem is caused by the extreme reflectivity of the walls, floors and ceilings of most studios. Granted, it is even easier to overdo the SPL with a PA speaker than with a conga, but it is amazing how little actual acoustic power it takes to really move people to dance. Quality trumps quantity. In addition, the clarity of rhythmic parts of the music is important and this usually gets seriously smeared by the glass and sheet rock walls with hardwood floors.

In theory adding subs would add rhythmic SPL at frequencies not likely to cause hearing damage, however the acoustics of most dance studios would support strong resonant modes and give very uneven bass. Putting in effective bass traps and broad spectrum absorption and diffusors on the walls and ceiling could get expensive and would require a serious commitment of the owner. In my experience, however, the sound has been much better and more danceable with lower SPLs in the acoustically treated performance spaces I have played in than in untreated dance studios, especially when there is enough audience in the house to absorb a lot of the reflected highs.

Regarding measurement, the Acoustic Alarm unit Bennett recommended looks interesting, thanks Bennett. Another possible option for a logging SPL meter, calibrated but not legally approved for OSHA enforcement, is the Etymotic Research ER-200DW7 personal dosimeter. It looks like a nice inexpensive pocket sized unit that will answer the questions and produce the Leq and cumulative dose plots needed to approach the question the OP has raised. I have not tried it but am considering purchasing one. Has anyone used this?
Etymotic Research, Inc. - ER?200DW7 Personal Noise Dosimeter with Data Logging
http://www.etymotic.com/pdf/er200dw7_user_manual.pdf
 
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Re: SPL metering, logging, alarm

Scott Helmke said:
Two systems that might fit the bill:
Welcome to SPLnet from Studio Technologies, Inc.
http://www.howloudisit.com

(I work at a dealership for both of these)
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Scott, I actually saw that TC Furlong is a dealer for these. They have all the right components, but they are intended for use in conjunction with a computer, which would not be the case in this scenario. Instructors do run their classes off of a computer, but they need to be looking at their playlist the whole time, not some other software. Because of that, a partly hardware solution would be necessary.
 
Re: SPL metering, logging, alarm

Daniel Postilnik said:
Bennett, I hope your reaction to those levels is not sarcastic. Our audio provider doesn't have an issue with building systems that produce such levels in a small enclosed space, just because a couple of deaf instructors require it.
Click to expand...

I am not being sarcastic. I well understand that delivering 105dBA is not challenging. I just wouldn't want to go to a dance studio that was within 10dB of that. To be fair, I wouldn't want to go to a dance studio at all, so clearly I am not the target market.
 
Re: SPL metering, logging, alarm

Jason Lavoie said:
ps: a well designed system will have even sound throughout the listening space, so this might require adjusting things so that the volume is not as even as it should be...
Click to expand...

A well designed system will provide coverage at the volumes required for each space. In a concert venue, yes, having equal coverage at all seats is desirable. In most other venues, it's NOT desirable to have the same SPL at all places in the room. This allows people to position themselves at a location with the SPL that they want.
 
Re: SPL metering, logging, alarm

Chris Nixon said:
There is a "platform" version of a buttkicker designed for bass players. I'm not sure what it's called but it might be worth researching. It'll still produce LF energy, but maybe you wouldn't need as much with them standing (dancing) on top of it.

It might look a bit like one of those dance machine simulators at arcades. Not sure if this is good or bad. :D~:-D~:grin:

Chris
Click to expand...

It's called Pleasure Board. It would take quite a few of them to fill a dance floor in a studio but maybe the general idea is worth it to go further into it. On the other hand at least one foot has to make contact with the floor in order to "hear" the sub.
 
Re: SPL metering, logging, alarm

Christian Tepfer said:
It's called Pleasure Board. It would take quite a few of them to fill a dance floor in a studio but maybe the general idea is worth it to go further into it. On the other hand at least one foot has to make contact with the floor in order to "hear" the sub.
Click to expand...
Just to be clear, nobody is in physical contact with the floor in these studios. They are on heavy stationary bikes.
 
Re: SPL metering, logging, alarm

Bennett Prescott said:
Yes, here's a hardware version: AcoPacific - SLARM(TM) Sound Level Alarm, ACOustAlarm(TM) and ACOustAlert(TM) Noise Alert Systems
Click to expand...
Bennett,

AcoPacific appears to have exactly what we're looking for. However, the aesthetics of this product--from the hardware device to the software interface--is incredibly unsexy. I'm only mentioning this because my employer is very aesthetically sensitive - it's part of the brand, and it's not cool for things to be "off-brand." Whatever.

More importantly, I'd like to present more than one option to my supervisor. Do you know of anybody else selling this kind of solution? Thanks.
 
Re: SPL metering, logging, alarm

George brings up some very good points but I take the view that OSHA and NIOSH do only address 8 hour periods and that references to shorter periods are included only to address how to relate varying levels of less than 8 hour duration to an overall 8 hour exposure. This gets into the general issue that exposure as it relates to hearing loss is a function of level and duration/time and that documenting only the levels, even if logged over time, does not by itself really address exposure as that is addressed by a statistical combination of level and duration.

Perhaps some basic points but if you are trying to address hearing loss or damage then a) most of the references such as OSHA and NIOSH address the effects of long term exposure, b) they address the exposure of individuals rather than just the SPL levels, c) they tend to address both administrative/passive and engineering/active responses and d) there may be different criteria for enacting a hearing monitoring system for exposures below those requiring direct action. A concept that many do not seem to realize is that OSHA and NIOSH do not restrict or even actually address the sound levels themselves, you can have any noise levels for any length of time, only that you have to limit the resulting exposure for individuals. Thus NIOSH and OSHA are likely difficult to directly apply to your situation. That does not mean you may not use information in them as a guideline for whatever you do, but you might have to be careful of exactly what it is seen as representing.

Another potential factor is the frequency response. OSHA and NIOSH use A-weighted overall SPL levels which are really not appropriate for reflecting the perceived loudness at higher levels. As others have noted, systems with the same same perceived loudness but varying frequency response may have quite different A-weighted SPL levels (or systems with the same SPL and different responses may have a different perceived loudness). So if it is the perceived loudness and not just potential hearing damage that is the issue then assessing only the overall A-weighted levels may not provide all of the relevant information.

On the aesthetics, most acoustical measurement equipment is going to be more focused on functionality, accuracy and reliability than aesthetics and you'll find few brands that are well known outside the industry, even B&K is probably not a well known brand name to the general public.

I guess the overall point is that you may need to decide what it is that you are really trying to do and achieve before looking at what hardware may be appropriate. It may be that something as simple as the Extech unit you referenced is all that is needed, however that or a simple logging SPL meter is not going to actually address loudness or exposure. And what is the intent of any measurements? Documenting or making apparent that they are producing sound levels that they consider as potentially causing hearing damage may not to be in Owner's best interests unless they actually act upon it.
 
Re: SPL metering, logging, alarm

Brad Weber said:
I guess the overall point is that you may need to decide what it is that you are really trying to do and achieve before looking at what hardware may be appropriate. It may be that something as simple as the Extech unit you referenced is all that is needed, however that or a simple logging SPL meter is not going to actually address loudness or exposure. And what is the intent of any measurements? Documenting or making apparent that they are producing sound levels that they consider as potentially causing hearing damage may not to be in Owner's best interests unless they actually act upon it.
Click to expand...
Brad,

We don't plan to use the official standards as hard rules for enforcement. I didn't even mention them in my original post. The idea is to be able to collect some data about sound levels currently being produced, compare that to the experience of being exposed to those levels in the studio for the allocated amount of time (for a customer, usually 45 minutes), reach a consensus among the decision makers at this company about what would be considered unhealthy, and then use the data to address customer complaints and recurring instructor violations.

I should mention that this is a company where everyone from the CEO, to the sound engineer, to the VP of operations, to the head of design, is expected to take classes on a regular basis to be in touch with what customers are experiencing. This is especially important when we want to be able to say to an instructor who is going deaf and taking others down with him/her: "Look, all these people of various ages and backgrounds who work for the company took your class and found it to be painfully loud, and we have data to indicate that you are above the guidelines recommended by several official bodies." Being able to monitor this data in realtime is also very handy, so we can identify the main offenders in the act.
 
Re: SPL metering, logging, alarm

Daniel Postilnik said:
AcoPacific appears to have exactly what we're looking for. However, the aesthetics of this product--from the hardware device to the software interface--is incredibly unsexy. I'm only mentioning this because my employer is very aesthetically sensitive - it's part of the brand, and it's not cool for things to be "off-brand." Whatever.

More importantly, I'd like to present more than one option to my supervisor. Do you know of anybody else selling this kind of solution? Thanks.
Click to expand...

Daniel,

The AcoPacific is just what came to mind. You might also look at Larson Davis, Extech, Casella, Quest, and of course B&K. Those are all hardware solutions, there are a handful of software or hybrid solutions as well but I can't speak about them as I did some contract work for one of those manufacturers.
 
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