desired dB levels for sound and recording studio

mesmith2 · Post by **mesmith2** » Fri Oct 15, 2004 6:09 am

i am a project manager assisting an architect retrofit an inoperable recording studio. we have recommended a variety of "bandaids" to help attenuate HVAC noise, rain on the roof, etc. however we have no means of measuring how good or how bad the solutions are.

if we purchase a Decible Meter to test before and after:
1. what is a good meter to buy?
2. what is the optimal dB reading for a studio and control room?
3. what is acceptable db readings for a studio and control room?
4. can you recommend an acoustical engineer, preferably in the Tidewater area of Virginia?

any other information you can provide to retrofit a 3rd floor recording studio with exposed ceiling (joist/deck) would be greatly appreciated!

knightfly · Post by **knightfly** » Sun Oct 17, 2004 3:37 pm

First, welcome to the board; your questions aren't quite clear in meaning to me; by dB levels in the studio, am I correct in assuming you mean Noise Criteria, or do you mean typical Sound Pressure Levels during operation?

AS to SPL meters, if you want one that's sensitive enough to measure critical NC levels in a digital-based studio, I'm not sure where you'd get one - it should be able to measure down to at least 20 dB spl, and I've yet to see one for under $4000 that can do that; you can get one for around $300 that will measure down to 30 dBa, including software and a cable that lets you use your PC for storage, etc; here's one I'm planning on ordering this week that's in that price range -

http://www.contractor-books.com/EX/407750.htm

This meter seems to be about the best "bang for buck" of the ones I've researched in this price range, but again if you're trying to determine REALLY quiet NC curves you would probably be better off renting one of the higher priced meters for your project.

As to Acoustic engineers on the East coast, I only know one I'd be confident in recommending, he's in the Durham, NC area - here's his website

http://www.overdublane.com/

If he's not close enough, he may be able to recommend someone closer to you; you'd need to contact Wes personally for that.

If you can clarify your questions 2 and 3, I'll be glad to answer those for you... Steve

mesmith2 · Post by **mesmith2** » Tue Oct 19, 2004 4:01 am

What i meant to say is that the studio that exists now is too loud for the Owner to record a CD b/c of the HVAC air flow in the space, the rain on the roof, the cars driving by, the jets overhead. WE want to be able to measure the current noise in the space (i assumed you would do this by decibel levels) and then take action to reduce the noise.

Am i making any sense yet?

AVare · Post by **AVare** » Wed Oct 20, 2004 1:52 am

Steve gave you great advice. You have a recommendation for a SPL Meter.

2. what is the optimal dB reading for a studio and control room?
3. what is acceptable db readings for a studio and control room?

You are asking for a simple answer to a complex question. Within simple (not complete or accurate!) terms, 20 dBA is a common design criteria for modern commercial studios.

What is acceptable? We don't know. All we know is that your client does not like what he/she has right now. To give a quick reference, movie theaters are around 30 dBA. That is for modern, not older ones.

Andre

mesmith2 · Post by **mesmith2** » Wed Oct 20, 2004 3:08 am

Thanks to you both for the assistance!

knightfly · Post by **knightfly** » Fri Oct 22, 2004 9:22 pm

OK, so you're looking for a way to measure noise floor in a studio then; the meter I linked to will NOT do this directly, as it (and anything else I've found for under $4000) doesn't measure below 30 dBA - for that, you need a meter that's designed for the increased sensitivity required to measure that quiet.

I just found these links today, so you can get an idea of price range;
This one goes down to 21 dBA, but unless you intend to do a lot of this work it would make more sense to find a local acoustics consultant and RENT one -

http://www.noisemeters.com/product/cr831.asp

This one is a little cheaper, goes down to 21 dBA also -

http://www.noisemeters.com/product/cr811.asp

Still, even this last one runs $ 2900...

Something else - HVAC noise is something that can be drastically reduced by using a larger, slower air handler - you would need to talk to a HVAC person who's done studios for this, as inexperienced techs won't know what you need for a studio system. The noise made by moving air is roughly equal to somewhere between the 4th and 5th POWER of the air velocity, so larger ducts and slower bigger fans make a HUGE difference in this noise source; so do specially shaped grilles, proper location of grilles away from engineers' ears, typical mic locations, etc.

Another possibly useful link on aircraft noise -

http://irc.nrc-cnrc.gc.ca/fulltext/ir760/ir760.pdf

http://irc.nrc-cnrc.gc.ca/fulltext/ir831/ir831.pdf

All the above are mainly for reference; if you've not studied sound control in serious depth, it is really easy to make assumptions that end up costing much more than they help. For this reason, you're wise to be asking about an acoustic consultant.

If you aren't able to work something out with Wes LaChot, I have another friend in Connecticut who has contacts in this field in several states; let me know, and he may know of someone closer to you... Steve

rod gervais · Post by **rod gervais** » Sat Oct 23, 2004 1:55 am

Most any 1/2 way decent acoustic engineer is going to be able to give you the information you're looking for.

But, this isn't as simple as just getting existing decibel levels....... you really need to be able to pinpoint what frequencies you're dealing with at particular levels in order to devise the designs you need to deal with those frequencies.

For example - suppose you go into a room and measure 60db of background noise - and thus you devise a wall that will develope a 60 STC rating - does the fact that this wall is rated to give you 60 db of sound reduction on a weighted scale do you any good if the 60db your meter picked up was an 83hz signal?

The answer my friend (is blowing in the wind?) is "no".........

Developing a wall assembly that will give you even a solid 40db of reduction (at that frequency) is a much more daunting task than picking and building an STC 60 wall assembly out of a book.

So if you don't deal with this right - you could choose and build a wall assembly - spend tons of money - and then find out that the problem noise is still there.

I don't think buying a meter makes sense - just get an acoustic engineer out there to determine what really existing for ambient background noise.

By the way - i think that Steve's reccomendation of Wes Lachot is an excellent one - although I don't know how available he is at this moment - this due to the fact that he is hot and heavy into the construction of his new home right now.

Good luck,

Rod

knightfly · Post by **knightfly** » Sat Oct 23, 2004 8:30 am

And you just heard from the friend in Connecticut - don't hate him 'cause he's a

drummer; love him 'cause he won't sugarcoat anything (and that's very very good considering the alternatives...) Thanks Rod - Steve