NOTE: Free essay sample provided on this page should be used for references or sample purposes only. The sample essay is available to anyone, so any direct quoting without mentioning the source will be considered plagiarism by schools, colleges and universities that use plagiarism detection software. To get a completely brand-new, plagiarism-free essay, please use our essay writing service.
One click instant price quote
... en adjusting for both noise, and sound quality. The most versatile type of ASP (automatic signal processor) comes from PILL circuitry that can provide either a BILL or a TILL response. In order to accomplish this, the instrument must have a minimum of two channel compression. (Tobin 1997) In effect, the audiologist can choose which type of processing better suits his client, while taking into consideration the subjective needs of his client. Presumably, PILL type hearing aids cost more than BILL or TILL type aids. Adding any programmable feature to a hearing aid generates more expense, and any consumer would need to reap considerable benefit with each increase in price.
Many users have tried, and failed, with recent approaches at signal processing for improving speech intelligibility in noise. These failures have led many hearing aid users, and their friends, to take a very cautious attitude toward new technology that claims to resolve some of these complaints. Some are convinced that the quality of the amplified signal provided by programmable hearing aids is not significantly better than their present non programmable aids. (Sandlin 1994) Regardless of these consumer attitudes, a PILL type aid will give a clinician more options when responding to client complaints of poor sound quality, or difficulty with speech intelligibility in noise. One of the more intriguing recent developments in hearing aid technology promises to deliver a more naturalistic sound quality and unequaled performance in noise.
Jonathan Spindel at the University of Virginia has shown advancing growth with a magnetic hearing aid. The new device uses a tiny implanted electromagnet attached to the round window of the inner ear to enhance hearing, reduce background noise, and eliminate feedback. (Source? 1998) Spindel believes that by leaving the human acoustic system intact and unobstructed, the device will be able to create constructive and destructive sound patterns in the cochlea. The magnetic aid consists of a microphone, a processing unit and an electromagnetic coil, all of which are implanted. For amplification purposes, the aid will generate sound waves that match the desired sound or voice. Combining both signals in phase will have the constructive effect of directly increasing the amplitude of the wave travelling over the basilar membrane. To account for noise reduction, the system is analogous to a FlowMaster&# 61668; muffler (see figure).
As shown, the signal processor generates a sound wave that is out of phase with the incoming signal. The two signals then combine in the cochlea and cancel each other out. The elimination of feedback is another substantial gain of this type of aid. Since the device does not transmit acoustic energy, magnetic energy at the cochlea generates no feedback potential. Our tests to date have shown that the signals produced with our magnetic hearing device are very nearly those of natural acoustic sound. (Spindel 1998) By not obstructing the normal hearing process and implanting the microphone in the ear, the magnetic hearing aid utilizes a unique feature. The natural resonance of the pinna and external auditory meatus is not impeded so in essence, the device uses our current anatomy as a fully functioning directional microphone.
Although the system is currently being tested on animals with favorable results, human testing will be necessary. The human subject, with a control module, can adjust the aid to reduce undesired sounds and produce maximum benefit. With the advent of miniature computer chips, the magnetic aid allows for an adjustable frequency / intensity analyzer to be implanted in the skull. The noise reduction possibilities for this type of aid are substantial, even if combined with other digital processing techniques. In conclusion, the advantage of noise reduction techniques in hearing aids is directly related to a reduction in hearing aid complaints, and an increase in client satisfaction. The directional microphone has been a valuable source for noise reduction since early Rock and Roll musicians wanted to reduce feedback during live performances as they got louder and louder.
A hearing aid fitted with a directional microphone receives benefit from the assumption that a person will most likely want to attend to a person he is directly facing. In reality, a good portion of our daily communication occurs in less than ideal circumstances. A conversation partner may be just leaving the room when he remembers something important to say, and for normal hearing individuals it is quite commonplace to yell an instruction from one room to another. In some cases, this will defeat the purpose of direc tivity. Thankfully, manufacturers have responded to these complaints by offering the ability to switch the sound focusing on or off, sometimes with a remote control. (Phonak 1997) Automatic signal processing in hearing aids is also a valuable advantage for noise reduction. By determining which frequencies are responsible for noise at different intensities, BILL, TILL, or PILL circuits can compress or limit those frequencies from being amplified.
Instead of a linear aid, in which all frequencies are amplified equally, these hearing aids reduce noise by limiting frequency bands. Once again, the question becomes a choice as to which frequency bands account for noise. If the hearing aid user is in a room with a noisy air conditioner, low frequency compression may eliminate that noise. If on the other hand the user works in an apiary, high frequency compression during conversation may be a better choice. Frequency range modification is also contingent upon the persons individual type of loss. For example, common sense dictates that a person with a high frequency hearing loss would probably not benefit from any circuit that provides treble reduction, unless it serves to prevent recruitment.
The magnetic hearing aid offers promises of exquisite noise reduction capability. In theory, the implantable processor will analyze sounds and isolate speech based on a users configurations. While the sources dont reveal how it is possible, or how it might work, the concept is valid. Regardless, each of these noise reduction techniques should be applied on an individual basis, accounting for a persons nature and degree of loss. Considering the price of inserting additional features into a hearing aid, an audiologist must also balance perceived need with a determination of what actual use might be, and the economical well being of his clients.
Perhaps in the future, correct hearing aid selection combined with ever advancing technology will yield the comment, Boy, this thing works great in a noisy restaurant! Alas, that is the nature of the beast. Bibliography: REFERENCES Bacon SP, Cook JA, Sammeth CA. (1997). Effect of Low-Frequency Gain Reduction and its Relation to Upward Spread of Masking. Journal of Speech, Language, and Hearing Research. 40 (2): 410 - 422. Beck LB, Bess FH, Studebaker GA. (1991).
Programmable and Automatic Noise Reduction in Existing Hearing Aids. The Vanderbilt Hearing Aid Report II. Parton, Maryland: York Press; 66 - 67. Bess FH, Christensen LA, Hedley-Williams A, Humes LE. (1997). A Comparison of the Benefit Provided by Well-Fit Linear Hearing Aids and Instruments with Automatic Reduction of Low-Frequency Gain. Journal of Speech, Language, and Hearing Research. 40 (3): 666 - 685 Tobin H. (1997).
Circuitry Options Average Conversation. Practical Hearing Aid Selection and Fitting. Baltimore, MD: Department of Veterans Affairs Rehabilitation Research and Development Service; 24. Phonak. (1997).
The New Standard in Noise-Reduction Technology. Micro Zoom. Phonak advertisement. Sandlin RE. (1994). Dispenser Resistance to Programmable Hearing Aids. Understanding Digitally Programmable Hearing Aids.
Needham Heights, MA: Allyn and Bacon; 253. Search B. (1998). The Audiologists Rehabilitative Tools: Hearing Instruments. Clinical Audiology: An Introduction. San Diego, CA: Singular Publishing Group, Inc. ; 469. Unlisted. (1998).
Electromagnetic Hearing Aid. Medical Materials Update. Online 5 (11). (For more information contact: Implantable Device Laboratory, P. O.
Box 430, Charlottesville, VA 22908; Tel: 804 / 924 - 2050, attn: Jonathan Spindel. ) Valente M. (1996). Amplifiers and Circuit Algorithms of Contemporary Hearing Aids. Hearing Aids: Standards, Options, and Limitations. New York: Thieme Medical Publishers, Inc; p. 189.
Free research essays on topics related to: high frequency, sound quality, signal processing, hearing, hearing aids
Research essay sample on Noise Reduction In Hearing Aids
