Nature's Noise Reduction

William J. Campbell M.S., Audiologist

Have you ever wondered how you were able to understand everyday conversation in all types of adverse (noisy) situations  prior to your hearing loss?  The complaint of “I hear everything but not clearly” is most commonly associated with inner ear hair cell degeneration in addition to other system weaknesses that develop with advancing age. Normal hearing is complex from top to bottom .  Nature has provided us with the capability of reducing confusion related to competing messages by means of an outer and middle ear mechanical system connected to the cochlea, brainstem, and cortex with all the necessary  bio-electric noise reduction circuitry included.   When the two ears are balanced in terms of their pick up patterns, the brain will have an easier time perceiving the  locations of multiple voices, thus enabling us to pinpoint the one of most interest .  This  auditory grouping ability assumes a mechanism capable of pitch, time, frequency, and correlational analysis------a lot to ask of one ear, let alone two,  with years of noise exposures, hereditary related glitches and just plain aging!!  Though the hearing aids of today are striving to perform their own noise reduction through directional microphone/computer processing,  none can match the exquisite performance of a normal hearing adult.  The best minds involved in the psychology/physiology  of hearing readily admit that the system is far more involved than most clinicians seem to admit.  There appears to be a healthy dose of magical thinking concerning what represents effective treatment  for hearing impairment.  Remember that a properly fitted hearing aid will enable you to understand speech significantly better in many instances but we must be realistic about the inherent complexities associated with our rehabilitative efforts.  The most important thing to remember when one is a hearing aid user is to have  regular check-ups to keep the aids in good operating condition.  Finally, wear your hearing aid full time for optimal results since the brain needs a robust ‘audio  baseline’ to make ongoing decisions about the communication environment.  Research suggests that given time, an impaired hearing system has the potential to rearrange some of its internal number crunching to maximize performance.

Suggested Readings

Journal of Acoustical Society of  America;  Vol. 118, No. 3,  September 2005, pp- 1614-1635

Journal of Acoustical Society of America,  Vol. 119,  No. 1,  January 2006,  pp  406-417

Journal of Acoustical Society of America,  Vol. 119,  No.  3,  March 2006,  pp  1597-1605

Journal of Acoustical Society of America,  Vol. 120,  No. 5, November 2006,  pp  2926-2937

Journal of Acoustical Society of America,  Vol. 121, No. 2, February 2007,  pp  1047-1055

Journal of Acoustical Society of America,  Vol. 121, No. 2, February 2007,  pp 1070-1076

Journal of Acoustical Society of America, Vol. 121, No. 3, March 2007, pp 1621-1631

Journal of Acoustical Society of America, Vol. 121, No. 4, April 2007, pp 2111-2126

Journal of Acoustical Society of America, Vol. 121, No. 5, May 2007, pp  2805-2818; 2832-2841

Journal of Acoustical Society of America, Vol. 121, No. 6, June 2007, pp 3655-3665

Journal of Acoustical Society of America, Vol. 122, No. 3, September 2007, pp 1713-1723

Ear & Hearing, Vol. 29, No.1, January 2008

Journal of Acoustical Society of America, Vol. 123,No. 2, February 2008, pp 1140-1153

Proc Nat Acad Sci., 2007; 104(51):20594-20599.

Journal of Acoustical Society of America, Vol. 123, No. 4, April 2008, pp 2237-2248

Journal of Acoustical Society of America, Vol. 124, No. 2, August 2008, pp 1130-1145; 1294-1305

Audiology Today, November/December 2008, Vol. 20, #6, pp 61-67

Journal of Acoustical Society of America, Vol. 124, #5, pp 3064-3075

Journal of Acoustical Society of America, Vol. 125, #4, April 2009, pp 2182-2188

Journal of Acoustical Society of America, Vol. 125, #5, May 2009, pp 3328-3345

Journal of Acoustical Society of America, Vol. 126, #3, November 2009, pp 2522-2535

Journal of Acoustical Society of America, Vol. 127, #2, February 2010, pp 943-954; 955-969

Journal of Acoustical Society of America, Vol 127, #4, April 2010, pp 2509-2520

Journal of Acoustical Society of America, Vol 127, #5, May 2010, pp 3075-3084