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[AUDITORY] low frequency noise in booth - UPDATE

Many thanks to all of you who responded to my call for help in dealing
with the 16-Hz noise I was encountering in my sound booth. I was
surprised to see how many people have had similar problems, because it's
something I've never run into before (though I guess I've only
calibrated in a total of 6 booths over my career). 

I tried several of the suggested solutions, including changing the
orientation of my coupler and placing the coupler on a soft surface
(neither of those helped). I checked the spectra of my speech and babble
calibration signals and determined that C weighting would have no impact
on them. Unfortunately, the noise level was still close to 70 dB C. 

Finally, skimming Arlinger (1997) made me think to try my **2-cc**
coupler - and that solved the problem. Measured in this coupler, the
noise is 40 dB C or 50 dB SPL, low enough for me to measure my signals
at my actual test levels. 

All of this raises a larger question about calibration, which I'll pose
in a new thread. 



~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 
Sarah Hargus Ferguson, Ph.D., CCC-A
Assistant Professor
Department of Speech-Language-Hearing: Sciences and Disorders 
University of Kansas 
Dole Center
1000 Sunnyside Ave., Room 3001 
Lawrence, KS  66045
office: (785)864-1116
Speech Acoustics and Perception Lab: (785)864-0610