Subject: Re: Hearing Loss "False Positive" From: Jeffrey Willson <willsonj@xxxxxxxx> Date: Tue, 28 Sep 2010 16:45:39 -0500 List-Archive:<http://lists.mcgill.ca/scripts/wa.exe?LIST=AUDITORY>--001636d352720c19bb049158c4df Content-Type: text/plain; charset=ISO-8859-1 Okay then, bottom line, what's your estimate of the percentage of teenagers who actually have a measurable and persistent noise-induced high-frequency hearing loss? Jeffrey On Tue, Sep 28, 2010 at 8:14 AM, Torben Poulsen <tp@xxxxxxxx> wrote: > Dear List, > > Thanks to Al for a clear explanation and 'calm down' statement. > I can add to things > > 1) In the audiometry standard ISO 8253-1 'Basic pure tone audiometry' an > example is given for the uncertainty: "The expanded measurement uncertainty > is evaluated for the determination of the hearing threshold level of a test > subject using air conduction audiometry at a frequency below 4 kHz without > masking and assuming that the requirements on ambient noise are met and that > no further uncertainty contribution arises from any other > sources. The uncertainty budget then has a form as presented in Table A.2. > ---I omit the table ---. The result is: Combined standard uncertainty: u = > 4,9 dB. > Expanded measurement uncertainty for 95 % coverage probability, rounded to > the nearest full decibel: U = 10 dB." > In other words there is a 10 dB uncertainty in the measurements itself - > for frequencies below 4 kHz. The uncertainty will increase at higher > frequencies (e.g. 4, 6, and 8 kHz) > > 2) It is well known that a fake hearing loss is often seen at 6 kHz when > thesholds are determined with a Telephonics THD39 or THD49 earphone. This > 'hearing loss' is about 5 dB and is possibly caused by an error in the > reference value for audiometer calibration (for this specific earphone). > This is mentioned as one of the conclusions in the Schlauch & Carney paper > that the UMNews refer to. > > Regards > Torben > > --001636d352720c19bb049158c4df Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Okay then, bottom line, what's your estimate of the percentage of teena= gers who actually have a measurable and persistent noise-induced high-frequ= ency hearing loss?<div><br></div><div>Jeffrey<br><br><div class=3D"gmail_qu= ote"> On Tue, Sep 28, 2010 at 8:14 AM, Torben Poulsen <span dir=3D"ltr"><<a hr= ef=3D"mailto:tp@xxxxxxxx">tp@xxxxxxxx</a>></span> wrote:<br>= <blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1p= x #ccc solid;padding-left:1ex;"> Dear List,<br> <br> Thanks to Al for a clear explanation and 'calm down' statement.<br> I can add to things<br> <br> 1) In the audiometry standard ISO 8253-1 'Basic pure tone audiometry= 9; an example is given for the uncertainty: "The expanded measurement = uncertainty is evaluated for the determination of the hearing threshold lev= el of a test subject using air conduction audiometry at a frequency below 4= kHz without masking and assuming that the requirements on ambient noise ar= e met and that no further uncertainty contribution arises from any other<br= > sources. The uncertainty budget then has a form as presented in Table A.2.<= br> ---I omit the table ---. The result is: Combined standard uncertainty: u = =3D 4,9 dB.<br> Expanded measurement uncertainty for 95 % coverage probability, rounded to = the nearest full decibel: U =3D 10 dB."<br> In other words there is a 10 dB uncertainty in the measurements itself - fo= r frequencies below 4 kHz. The uncertainty will increase at higher frequenc= ies (e.g. 4, 6, and 8 kHz)<br> <br> 2) It is well known that a fake hearing loss is often seen at 6 kHz when th= esholds are determined with a Telephonics THD39 or THD49 earphone. This = 9;hearing loss' is about 5 dB and is possibly caused by an error in the= reference value for audiometer calibration (for this specific earphone). T= his is mentioned as one of the conclusions in the Schlauch & Carney pap= er that the UMNews refer to.<br> <br> Regards<br> Torben<br><br></blockquote></div></div> --001636d352720c19bb049158c4df--