Re: AUDITORY Digest - 22 May 2002 to 23 May 2002 (#2002-83) (Jont Allen )

Subject: Re: AUDITORY Digest - 22 May 2002 to 23 May 2002 (#2002-83)
From:    Jont Allen  <jba(at)auditorymodels.org>
Date:    Fri, 24 May 2002 15:07:44 -0400

Automatic digest processor wrote:

>There are 2 messages totalling 106 lines in this issue.
>
>Topics of the day:
>
>  1. Transfer function of middle ear
>  2. Middle ear transfer function
>
>----------------------------------------------------------------------
>
>Date:    Thu, 23 May 2002 07:51:18 -0400
>From:    Jont Allen <jba(at)AUDITORYMODELS.ORG>
>Subject: Transfer function of middle ear
>
>Vivek,
>The middle ear acts as a high pass filter, with a cutoff about 800 Hz.
>It is almost
>flat from 800 to 20 kHz or so, depending on the size of the middle ear
>(i.e.,
>the head). There is a very large literature, much of it in the Jol. of
>the Acoustical
>Soc. of America. Look at the following papers, for example:
>
>(at)article{Guinan67,
>author={Guinan, J. J. and Peake, W. T.},
>year={1967},
>title={Middle-ear characteristics of anethetized cats},
>journal=JASA,
>volume= {41},
>pages={1237-1261}
>        }
>
>(at)inproceedings{Shaw78,
>author={Shaw, Edgar A. G.},
>year={1978},
>booktitle={Acoustical Factors Affecting Hearing Aid Performance},
>title={The acoustics of the external ear},
>editor={Studebaker, G. A. and Hochberg, I.},
>publisher={University Park Press},
>address={Baltimore, MD},
>pages={109--125}
>        }
>
>(at)article{Stinson82,
>author={Stinson, M., Shaw, E.A.G. and Lawton, B.W.},
>year={1982},
>title={Estimation of acoustical energy reflectance at the eardrkum from meas
>urements of pressure distribution in the human ear canal},
>journal=JASA,
>volume={72},
>pages={ 766-773}
>        }
>
>(at)article{Puria91b,
>author={Puria, Sunil and Allen, Jont B.},
>year={1991},
>title={A parametric study of cochlear input impedance},
>journal=JASA,
>volume={89},
>number={1},
>month=jan,
>pages={287-309}
>        }
>
>
>--
>Jont B. Allen,     jba(at)auditorymodels.org;   908/654-1274voice; 908/789-9575 fax
>382 Forest Hill Way
>Mountainside NJ 07092
>http://auditorymodels.org/jba
>
>
>``It is hard to abandon the feeling that the unfamiliar is absurd and illogical.''
>        --G.A. Miller, p. 5 of his book `Language and communication'
>
>------------------------------
>
>Date:    Thu, 23 May 2002 15:50:49 +0100
>From:    "Brian C. J. Moore" <bcjm(at)CUS.CAM.AC.UK>
>Subject: Middle ear transfer function
>
>Dear List,
>
>While I always hesitate to disagree with Jont Allen, my interpretation of
>the literature is that the middle ear transfer function, measured as the
>ratio of cochlear pressure to pressure at the ear drum, is not flat from
>800 Hz to about 20 kHz, but is more like a bandpass function, rolling off,
>in humans, above 5 kHz.
>
I do agree with Brian, that there is some roll-off above a few kHz.
There is a great deal
of variability between ears on this point. It is my interpretation of
the data,
That really high quality ears (having no dammage) show less of this rolloff
between 5 and 20 kHz. But there is no doubt that it is there in the majority
if not all ears, to different degrees.  I am guided by Fig. 10 of
Puria and Allen, JASA, Vol. 104(6), Dec. 1998 page 3474.
I have placed a .jpg file of this figure at the following URL:

http://auditorymodels.org/jba/images/MEFig10.jpg

This figure shows a 10 or so dB attenuation between 5 and 20 kHz.
That is 10 dB in 2 octaves, or 5dB/oct.
Remember, speech contains information from 300 Hz to 7 or 8 kHz.
So this effect is quite small on the speech signal.

Jont

> See:
>
>Puria, S., Rosowski, J. J. and Peake, W. T. (1997). Sound-pressure
>measurements in the cochlear vestibule of human-cadaver ears, J. Acoust.
>Soc. Am. 101, 2754-2770.
>
>Aibara, R., Welsh, J. T., Puria, S. and Goode, R. L. (2001). Human
>middle-ear sound transfer function and cochlear input impedance, Hear. Res.
>152, 100-109.
>
>
>Brian C. J. Moore, Ph.D., FMedSci, FRS
>Professor of Auditory Perception,
>Department of Experimental Psychology,
>University of Cambridge,
>Downing Street,
>Cambridge CB2 3EB,
>England
>Tel. + 44 1223 333574
>Fax. + 44 1223 333564
>http://hearing.psychol.cam.ac.uk/
>
>------------------------------
>
>End of AUDITORY Digest - 22 May 2002 to 23 May 2002 (#2002-83)
>**************************************************************
>

--
Jont B. Allen,     jba(at)auditorymodels.org;   908/654-1274voice; 908/789-9575 fax
382 Forest Hill Way
Mountainside NJ 07092
http://auditorymodels.org/jba


``It is hard to abandon the feeling that the unfamiliar is absurd and illogical.''
        --G.A. Miller, p. 5 of his book `Language and communication'