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CSD 3000 DEAFNESS IN SOCIETY. Topic 8 HEARING AIDS AND ASSISTIVE TECHNOLOGY. Modern Hearing Aid Design. Miniturization Enhanced signal processing Multiple memories Noise reduction Feedback control Programmability Digital processing Multiple channels. Important Hearing Aid Components.
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CSD 3000DEAFNESS IN SOCIETY Topic 8 HEARING AIDS AND ASSISTIVE TECHNOLOGY
Modern Hearing Aid Design Miniturization Enhanced signal processing • Multiple memories • Noise reduction • Feedback control • Programmability • Digital processing • Multiple channels
Important Hearing Aid Components • Batteries Sizes and materials • Microphones Directional and omnidirectional • Amplifiers • Receivers External air conduction, bone conduction, vibrotactile
Other Optional Features • On/off switch • Telecoil • Separate circuit to use with a telephone receiver or an induction loop system • Reduces feedback and improves interference from background noise • Volume Control • Earmold • CD-ROM Ch.07.06 shows some examples of common earmold styles • CD-ROM Ch.07.07 shows a video example of taking an earmold impression
Hearing Aid Fitting Considerations What does the audiologist consider when making the recommendation for amplification? • Hearing aid style
Major Hearing Aid Styles • Body hearing aids • Eyeglass hearing aids • Behind the ear hearing aids • In the ear hearing aids • Completely in the canal hearing aids CD-ROM Ch.07.01 illustrations of every angle of BTE, ITE, ITC, and CIC
Body and Eyeglass Hearing Aids Popular in the1950’s and 1960’s • CD-ROM Ch7.03 shows image of body hearing aid Receiver is external Needs an earmold • Advantages High gain, no feedback, large controls • Disadvantages Stigma, monaural fittings only,microphone placement • Eyeglass style All components are internal but breakdown is common
Behind the Ear Hearing Aids All hearing aid components built into a case that fits behind the ear Couples to the ear via earmold • CD-ROM Ch.07.04 • Advantages • Flexibility • Good choice for kids • Compatibility with direct audio input • Good feedback control • Microphone placement • True binaural fittings • Durable
In the Ear Hearing Aids All hearing aid components fit completely in the ear CD-ROM Ch.07.05 Biggest advantage is customizing the hearing aid to the individual
Completely in the Canal Hearing Aids All hearing aid components fit completely in the external canal CD-ROM Ch.07.01 • Advanages Easy to use, Reduction of occlusion effect, Reduced feedback, Improved localization ability, Less gain needed, No wind noise, No cerumen problem, Easy use with phone, Invisible, Greater high frequency emphasis • Disadvantage Size demands
Hearing Aid Fitting Considerations What does the audiologist consider when making the recommendation for amplification? • Hearing aid style • Level of technology
Hearing Aid Technology • Analog • Oldest form of signal processing • The signal is processed in a manner that is continuously varying over time • Programmable • Uses analog signal processing with digital control • Digital • Signal is digitized, manipulated, then converted back to analog form
Hearing Aid Fitting Considerations What does the audiologist consider when making the recommendation for amplification? • Hearing aid style • Level of technology • Monaural vs binaural fitting
Advantages to Binaural Amplification • Localization • Binaural summation • Elimination of a bad side • Binaural squelch • Auditory deprivation Koop video
Other Kinds of Amplification Devices Tactile hearing aids • Used by individuals who can’t benefit from traditional amplification • Delivers vibrotactile stimulation • Limited frequency resolution • Main advantage is as a supplement to visual and contextual cues
Other Kinds of Amplification Devices Implantable hearing aids • Middle ear implants • Bone-anchored hearing aids • Cochlear implants
Cochlear Implants Internal components • Internal receiver • Electrode array • CD-ROM Ch.07.10 External components • Microphone • Connecting cables • Speech processor • Transmitter • CD-ROM Ch.07.08 shows first body worn speech processor • CD-ROM Ch. 07.09 is typical earlevel processor
What the Major Components Do.. Microphone Speech processor Transmitter Electrode array CD-ROM Ch.07.11 illustrates what the implant looks like worn
Wireless Amplification Systems Environmental factors that make speech understanding difficult • Reverberation • Background noise CD ROM Ch.07.15 and Ch.07.16 illustrate typical listening conditions in a classroom
Major Types of Wireless Systems FM systems • Personal FM trainers • CD-ROM Ch. 07.12 shows an example • Soundfield FM systems Infared systems Induction loop systems CD-ROM Ch.07.13 audio example