Karl,
I have some material on sound absorption and the "metric sabin". From
that and the application presented in my source, this unit has
dimensions of [L]^2. One multiplies a coefficient (based on specific
frequency and type of material) by the area of that material to obtain
sound absorption in "metric sabins". The coefficients themselves are
unitless (much like emissivity, albedo, etc.) so any tables of
coefficients you have should still be valid.
The equation that uses these in the reference I hold is
T_60 = (0.16 s/m)(V/a)
where
T_60 (T sub 60) is the reverberation time in seconds (time required
for a 60 dB rolloff in SPL),
V is the volume of the space in m3, and
a is the sum of the absorptions for the individual surfaces.
One multiplies each surface area (in m2) by the proper coefficient
(depending on material and frequency) and then sums these numbers for
all the surfaces in the ensonified volume.
If you have been using measurements in square and cubic feet, then you
probably have an equation of the form
T_60 = (0.0485 s/ft)(V/a).
Alternatively, one could maintain the magnitude of the constant 0.16 and
adjust the coefficients, but this is unlikely to have been done. A
coefficient of 1.00 would indicate total absorption by the material
regardless of the units used to measure a piece of it.
Occupancy by people, furniture, and so forth would of course reduce the
reverberation times.
I hope this helps answer your questions. Please let me know directly or
on this list if you need any clarification of the above.
regards,
Jim Frysinger
"Karl G. Ruling" wrote:
>
> Does anyone know the SI or metric equivalent of the sabine? The sabine is
> the unit of sound absorbtion of one square foot of a perfect sound absorber
> (an open window, e.g.). I can't find the sabine listed in IEEE/ASTM SI 10
> or in the NIST guide.
> Best regards,
> Karl G. Ruling
> Technical Standards Manager
>
> The Entertainment Services & Technology Association
> 875 Sixth Avenue, Suite 2302
> New York, NY 10001
> +1-212-244-1505
> Fax: +1-212-244-1502
--
Metric Methods(SM) "Don't be late to metricate!"
James R. Frysinger, CAMS http://www.metricmethods.com/
10 Captiva Row e-mail: [EMAIL PROTECTED]
Charleston, SC 29407 phone/FAX: 843.225.6789
