Re: [AUDITORY] how often should we calibrate?

[Jeremy Federman <jeremy.federman@xxxxxxxxxxxxxx>]

Hi - 

Although I sympathize with your desire not to have to train all your
research assistants to do otoscopy, how do you plan on eliminating middle
and outer ear problems as potential confounds without looking in subjects'
ears?  It would seem to me the benefits of inserts (e.g., disease control,
eliminate risk of ear canal collapse, increased inter-aural attenuation,
etc.) outweigh the training requirements especially considering the risk for
possible contamination of your experimental results.  Your method of using
supra-aural phones for calibration is unclear to me.  Regardless, the two
types of phones you are using likely have different response
characteristics.

Regarding calibration frequency, we typically calibrate prior to the first
test session of each day as an absolute bare minimum.  Frequently, we
calibrate more often depending on the equipment and setup involved.  We have
many people using equipment, so our risk for being out of calibration may be
higher than others.  In any case, if I were you, I would ask myself, "How
much risk am I willing to put up with?"  In other words, would the savings
in time (and cost) spent on calibration be worth losing data if calibration
problems were discovered after test sessions, or, worse, not discovered at
all...

With kind regards,

Jeremy

On 1/7/08 4:31 PM, "Ferguson, Sarah Hargus" <safergus@xxxxxx> wrote:

> Hello all - As I said, my recent trouble with booth noise has raised a
> larger question for me. With the digital equipment most of us are using
> nowadays, how often do we really need to calibrate?
> 
> I can't use insert phones for all of the experiments in my lab, mostly
> because of the time it would take to teach every lab member how to
> perform otoscopy. So my plan for experiments using supra-aural phones is
> to measure the maximum output of the system for the supra-aural phones,
> use that level to determine the needed attenuator settings, and then use
> insert phones to confirm that the attenuator is doing what it's supposed
> to do. 
> 
> Certainly I need to go through these steps at the beginning of an
> experiment. But how often should I repeat them? I was taught, way back
> when, to calibrate every day that data were being collected. But if the
> signal is a digital file stored in the computer, and the signal is being
> delivered through digital equipment, is that really necessary?
> 
> ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
> 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
> http://www.ku.edu/~splh/Faculty/FergusonBio.html
> 
> 

-- 
Jeremy Federman, MS, CCC-A
PhD Student & Research Assistant
Dam Maddox Hearing Aid Research Lab
Department of Hearing & Speech Sciences
Vanderbilt University
Nashville, TN  37232
Jeremy.federman@xxxxxxxxxxxxxx