AES Technical Committee

Hearing and Hearing Loss Prevention

Chair:	Robert Schulein	(Send E-mail)
Vice Chair:	Michael Santucci	(Send E-mail)
Vice Chair:	Jan Voetmann	(Send E-mail)

Would you like to contribute?

If you are interested in participating in the committee's work please send an e-mail to the chair Robert Schulein. Please indicate in your e-mail that you are interested in the AESTC-HHLP. We welcome those interested in joining the committee to attend a future committee meeting. AES and non AES members are always welcome. Please Note: You do not have to be an AES member to join this committee, however you must be an AES member to serve as Chair or Vice-Chair of the committee. The committee communicates by means of an e-mail reflector site. This committee meets approximately evety 6 months at alternate European and US conventions.

Emerging Technology Trends

Current technology in the field of audiology allows for the primary measurement of hearing loss by means of:

1. Minimum sound pressure level audibility vs. frequency producing an audiogram record. Such a record is used to define hearing loss in dB vs. frequency.

2. Measurement of speech intelligibility masked by varying levels of speech noise. Such measurements allow individuals to compare their speech intelligibility signal-to-noise ratio performance to the normal population.

Other tests are commonly used as well for diagnosis as to the cause of a given hearing loss and as a basis for treatment. Within the past ten years, new tests have evolved for diagnosing the behavior of the cochlea by means of acoustical stimulation of hair cells and sensing their resulting motion. Minute sounds produced by such motions are referred to as otoacoustic emissions.

Measurement systems developed to detect and record such emissions work by means of distortion product detection resulting from two-tone stimulations as well as hair cell transients produced from pulse-like stimulations. Test-equipment design for such measurements are now in common use for screening newborn children. Additional research is being conducted directed at using such test methods to detect early stages of hearing loss not yet detectable by hearing-threshold measurements.

The AESTC-H&HLP is currently working to establish a cooperative relationship between researchers in this field and AES members, who will serve as evaluation subjects.

Currently there is no known cure for what is referred to as sensory neural hearing loss, in that irreparable damage has been done to the hearing mechanism. Such loss is commonly associated with aging and prolonged exposure to loud sounds, although it is well established that all individuals are not affected to the same degree. Considerable research is ongoing with the purpose of devising therapies leading to the activation of cochlear stem cells in the inner ear to regenerate new hair cells. There are however drug therapies being introduced in oral form to prevent or reduce damage to the cilia portion of hair cells in cases where standard protection is not enough, such as in military situations.

Hearing instruments are the only proven method by which sensory neural hearing loss is treated. In general the task of a hearing instrument is to

use signal processing and electroacoustical

means to compress the dynamic range of sounds in the real world to the now limited audible dynamic range of an impaired person. This requires the

implementation of level-dependent compression circuits to selectively amplify low-level sounds and power amplification and high-performance

microphone and receiver transducers fitted into miniature packages. Such circuitry is commonly implemented using digital signal processing techniques powered by miniature 1-volt zinc-air batteries.

In addition to dynamic-range improvements, hearing aids serve to improve the signal-to-noise ratio of

desired sounds in the real world primarily for better speech intelligibility in noise. Currently miniature directional microphone systems with port

spacings in the 5-mm range are being used to provide improvements in speech intelligibility in noise of 4 to 6 dB. Such microphones have become

rather sophisticated, in that many designs have directional adaptation circuits designed to modify polar patterns to optimize the intelligibility of desired sounds. In addition some designs are

capable of providing different directional

patterns in different frequency bands. Furthermore, some hearing aid manufacturers have introduced products using second-order directional

microphones operating above 1 kHz with some success.

In many situations traditional hearing aid technology is not able to provide adequate improvements in speech intelligibility. Under such circumstances wireless transmission and

reception technology is being employed to essentially place microphones closer to talkers mouths and speakers closer to listeners ears. This

trend appears to offer promise enabled by the evolution of smaller transmitter and receiver devices and available operating-frequency allocations. Practical devices using such technology are now being offered for use with cellular telephones. This is expected to be an

area of considerable technology and product growth.

Another hearing disorder, tinnitus, is commonly experienced by individuals, often as a result of ear infections, foreign objects or wax in the ear, and injury from loud noises. Tinnitus can be perceived in one or both ears or in the head. It is usually described as a ringing, buzzing noise or a pure tone perception. Certain treatments for tinnitus have been developed for excessive

conditions in the form of audio masking, however most research is directed toward pharmaceutical solutions and prevention. In Europe, psychological

assistance to help individuals live with their tinnitus is a well established procedure.

Hearing-loss prevention has become a major focus of the AESTC-H&HLP due to the fact that a majority of AES members come in contact with high-level

sounds as a part of the production, creation, and reproduction of sound. In addition, this subject has become a major issue of consumer concern due to the increased availability of fixed and portable audio equipment capable of producing damaging sound levels as well as live sound performance attendance. One approach to dealing with this issue is education in the form of communicating acceptable exposure levels and time guidelines. Such measures are however of limited

value, as users have little practical means of gauging exposure and exposure times. This situation represents a major need and consequent opportunity for the AESTC-H&HLP, audio equipment manufacturers, and the hearing and hearing-conservation communities.

Current and Future Activities

1. The TC is in the process of developing workshops and Tutorials for the 124 and 125 AES conventions in Amsterdam, The Netherlands, and San Francisco, CA.

2. The TC is in the initial stages of developing a proposal for an AES Conference with the working Title “Engineering Technology for Hearing Conservation and Sound Reproduction”.

3. The TC is looking for a research partner to study the relationship between individual Otoacoustic Emissions data and Hearing Threshold Data. We have identified a potential research partner and are now developing a research plan.

4. The TC is working on implementing a hearing screening and consultation program at the 126th AES Convention in Munich, Germany

5. The TC organized a "How Loud Do You Listen" test and demonstration in conjunction with the NHCA (National Hearing Conservation Association). This activity took place at the 121 AES Convention in San Francisco. We expect to have results from this test program by October of 2008.

Committee Members

Elizabeth Cohen	Ivan Stamac	Jan Voetmann
Peter Mapp	Richard S Stroud	Robert Schulein
William L Martens	Bozena Kostek	Ian Kuhn
Laurie Wells	Michael Santucci	Scott Snyder
Brian Fligor	Marilee Potthoff	Jeff Schwartz
Benjamin Kanters	Jason Corey	Preben Kvist
Waldo Nogueira	Lawrence Revit	Pam Gunn
Beno Groothoff	Jeanne Stiernberg	Neil Cherian
Keith Gordon	J M Woodgate	Marshall Chasin
Ainslie Harris	John Usher	Gonzalo J. Rodriguez
Christopher Struck	Omatali Beckett	Vicki Silver
Benjamin Mesiti	Michiel Van Eeden	Joseph Blasingame
Anton Schlesinger	Colin Bigland	Stephen Ambrose
John Dawson	Jan van Doorn	Zhong Xuan
Kathy Peck	Kristin Bidwell	Linda Pink
Tom Fritsch	Retnaguru Sandrakasan	Dorte Hammershoi

To request membership in this Technical Committee please e-mail the Chair by using the link above.