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dB reference for acoustic reflexes

Lisa-Jane Moody bunningm at MAIL.AUSTASIA.NET
Mon Nov 25 02:33:08 EST 1996


Dear Auds,

As I understand it, ipsi reflexes are measured in "dBSPL in 2cc Coupler",
as this is how the probe is calibrated, while contra's delivered via the
headphone are in dBHL.

For 226Hz probe tone, dBSPL in 2cc Coupler is approx dBSPL in the ear canal
if C max (maximum total compliance) is 2cc.

This can be converted to dBHTL by subtracting Minimal Audible Pressure
values.

If Cmax is not 2cc, further correction is necessary: double compliance,
subtract 6dB:
	Cmax (cc)	Correction (dB)
	0.5		+12
	1.0		+6
	1.5		+2		
	2.0		0
	2.5		-2
	3.0		-4
	4.0		-6
	5.0		-8

I hope this is helpful. 
Kind regards,
Lisa-Jane Moody
Chief Audiologist
The Geelong Hospital
Victoria Australia


----------
> From: Jeffrey Sirianni <audioman at HCTC.NET>
> To: audiolog at net.bio.net
> Subject: dB reference for acoustic reflexes
> Date: Wednesday, 20 November 1996 15:39
> 
> Forwarded from personal email received:
> 
> >Date: Mon, 18 Nov 1996 17:49:10 -0800 (PST)
> >From: nancy nigg <nancy_nigg at csufresno.edu>
> >To: audioman at HCTC.NET
> >Subject: dB reference for acoustic reflexes
> >Newsgroups: bionet.audiology
> >Organization: California State University, Fresno
> >
> >Can anyone explain why ipsilateral reflexes are measured in dBSPL
> >while contralateral reflexes are measured in dBHL?  I have searched a
> >number of books and can not find the reason why.  Any help would be
> >appreciated.  Thanks, Nancy
> >
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