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Re: High-frequency hearing in humans

For many years extended high frequencies (> 8 kHz) were believed to have limited value in speech perception. Recent studies have shown that extended high frequencies and extended bandwidth in hearing aids may play an important role in improving sound quality (Ricketts, Ditt­berner, & Johnson, 2008); music quality (Moore & Tan, 2003); speech perception (Pittman, 2008; Stelmachowicz,  Lewis,  Choi, & Hoover, 2007; Stelmachowicz, Pittman, Hoover, & Lewis, 2001; Stelmachowicz, Pittman, Hoover, Lewis, & Moeller, 2004); spatial awareness (Best et al., 2005; Kidd, Arbogast, Mason, & Gallun, 2005; Behrens, Neher, Burmand, Johannesson, 2007); and loudness perception (Soeta, & Nakagawa, 2008).  Considering the additional information provided by extended high frequency acoustical information, it is logical to assume that significant differences in this region may impact speech localization, sound quality, and understanding.    
There are other important clinical reasons why we are interested in assessing human thresholds at extended high frequencies (> 8kHz). Interest in establishing thresholds at high frequencies is based on the fact that most commonly encountered sensorineural hearing losses affect the high frequencies first.  It has been suggested that extended high frequency audiometry (8-16 kHz) might be more sensitive than conventional frequencies (250-8000 Hz) in detecting the early sign of hearing impairment in the most commonly occurring otological conditions such as presbycusis (Ahmed et al., 2001; Wiley et al., 1998), noise induced hearing loss (Ahmed et al, 2001; Somma, et al., 2008) and ototoxicity (Fausti, Henry, Hayden, Phillips, & Frey, 1998).  Early detection of these commonly occurring hearing impairments through extended high frequency audiometry may allow more effective measures for protection and prevention of hearing loss.  
The effect of middle-ear pathologies on extended high frequencies rather than conventional frequencies has also been investigated.  It has been shown that children with histories of otitis media have hearing loss at extended high frequencies (Ahonen & McDermott, 1984; Dieroff & Schuhmann, 1986; Lopponen, Sorri, Pekkala, & Penna, 1992; Margolis, Saly, & Hunter, 2000; McDermott, Fausti, & Frey, 1986).  This is due to transmission of OM-related toxins through the round window membrane (Margolis et al., 2000).  
Navid Shahnaz, Ph.D., Aud. (C)
Associate Professor
School of Audiology & Speech Sciences
Faculty of Medicine
University of British Columbia
2177 Wesbrook Mall, Friedman Building
Vancouver, BC Canada V6T 1Z3

Tel. 604- 822-5953
E-mail: nshahnaz@xxxxxxxxxxxxxxxxxx
Website: http://www.courses.audiospeech.ubc.ca/navid

“U.S. News and World Report” profiles Audiology as one of the Best Careers for 2009.

From: AUDITORY - Research in Auditory Perception [AUDITORY@xxxxxxxxxxxxxxx] On Behalf Of Piotr Majdak [piotr@xxxxxxxxxx]
Sent: Tuesday, January 25, 2011 1:27 AM
To: AUDITORY@xxxxxxxxxxxxxxx
Subject: High-frequency hearing in humans

Dear list,

I'm looking for the reasons for the good high-frequency* hearing  in humans.

The reasons I have until now are actually the obvious ones:
* Pinna localization cues
* Interaural level cues (ILD, they actually start to work from around 2 kHz)

What do you think: if there were no need for the ILD and pinna cues,
would there be any other reasons?


*) say, above 8 kHz

Piotr Majdak
Psychoacoustics and Experimental Audiology
Acoustics Research Institute <http://www.kfs.oeaw.ac.at>
Austrian Academy of Sciences <http://www.oeaw.ac.at/>
Wohllebengasse 12-14, 1040 Vienna, Austria
Tel.: +43 1 51581-2511
Fax: +43 1 51581-2530