[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: low frequency noise in sound booth
Dear List
We've had the exact same calibration problems in our sound booths - mostly caused by a ventilation system that produced very large SPL in the 10-20 Hz region.
When using a portable sound level meter, there is often not a selectable high-pass cut-off. However there is often the option to select 'C' weighting which is much flatter than the 'A' weighting - flat from 100 Hz - 3 kHz and thus well suited for speech level calibration. So that has been our solution to the calibration issue.
There is a good overview of weighting functions on http://en.wikipedia.org/wiki/A-weighting
Regards
Lars
Lars Bramsløw, Ph.D.
Oticon A/S, Audiology
Kongebakken 9
DK-2765 Smørum
lab@xxxxxxxxx
+45 39 13 85 42
-----Original Message-----
From: AUDITORY - Research in Auditory Perception [mailto:AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Stuart Rosen
Sent: 15. december 2007 08:56
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: Re: low frequency noise in sound booth
I too have had this problem. In our quiet room in central London, you
can in fact, just about hear the tube trains as they pass under our
building. But even when it appears to be completely silent, our spectrum
analyser shows strong low frequency sound.
But A-weighting is not necessarily the best way to deal with this
problem and is often inappropriate depending upon what one is trying to
measure. Our spectrum analyser has the option of summing the power over
a specified frequency range, so I simply restrict the measuring range to
something like 50 Hz-10 kHz.
Yours - Stuart
--
/*------------------------------------------------*/
Stuart Rosen, PhD
Professor of Speech and Hearing Science
Dept of Phonetics & Linguistics
UCL
4 Stephenson Way
London NW1 2HE
England
Directions to Wolfson House (where I am based):
http://www.phon.ucl.ac.uk/dept/maps.html
Tel: (+ 44 [0]20) 7679 7404
Admin: (+ 44 [0]20) 7679 7401
Fax: (+ 44 [0]20) 7679 5107
Email: stuart@xxxxxxxxxxxxxx
Home page: http://www.phon.ucl.ac.uk/home/stuart
/*------------------------------------------------*/