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_ Six _

Joined: 03/06/06
Posts: 1398
Loc: Liverpool

Transmission loss in acoustic materials
#722036 - 31/03/09 07:43 PM

I have found an equation to calculate transmission loss however its units of mass are lb/ft squared.

TL (dB) = 14.5log M+23

where TL is the transmission loss in dB and M is the surface density in pounds per square foot.

Is there a more up to date version that uses metric units?

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mankind-nil

Joined: 07/06/06
Posts: 117
Loc: Edinburgh, UK

Re: Transmission loss in acoustic materials new

[Re: _ Six _]
#722628 - 02/04/09 10:53 PM

The transmission loss is also a function of frequency, so the equation you've provided doesn't really make sense to me.
Try here for a useful paper explaining transmission loss.

Equation 1 gives TL= 20 log10 (mf) - 48
where m is the mass (in kg) per unit area (in m2) and f is frequency (in Hz), though this equation is only valid for part of the frequency spectrum, as explained in the paper.

ps June '06 was a great time to join the forums (or is it fora?) !

--------------------
MacBook, Logic 8, headphones, too many ideas...
www.mankind-nil.co.uk

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_ Six _

Joined: 03/06/06
Posts: 1398
Loc: Liverpool

Re: Transmission loss in acoustic materials new

[Re: _ Six _]
#723127 - 05/04/09 07:30 AM

Thanks mate. That's what I was looking for.

The first equation doesn't include the frequency, that's why it doesn't make much sense. I haven't got the book to hand but it was detailing the density of a mass and the TL relationship.

Cheers for that paper. Exactly what I need

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mankind-nil

Joined: 07/06/06
Posts: 117
Loc: Edinburgh, UK

Re: Transmission loss in acoustic materials new

[Re: _ Six _]
#723389 - 06/04/09 10:49 AM

No probs, glad it helped.
All the best.

--------------------
MacBook, Logic 8, headphones, too many ideas...
www.mankind-nil.co.uk

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