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 1. Batteries Sizes and materials 2. Microphones Directional and omnidirectional 3. Amplifiers 4. Receivers External air conduction, bone conduction, vibrotactile

Other Optional Features 1. On/off switch 2. Telecoil  Separate circuit to use with a telephone receiver or an induction loop system  Reduces feedback and improves interference from background noise 3. Volume Control 4. Earmold CD-ROM Ch shows some examples of common earmold styles CD-ROM Ch shows a video example of taking an earmold impression

Hearing Aid Fitting Considerations What does the audiologist consider when making the recommendation for amplification? 1. Hearing aid style

Major Hearing Aid Styles 1. Body hearing aids 2. Eyeglass hearing aids 3. Behind the ear hearing aids 4. In the ear hearing aids 5. Completely in the canal hearing aids CD-ROM Ch 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 Advantages 1. Flexibility 2. Good choice for kids 3. Compatibility with direct audio input 4. Good feedback control 5. Microphone placement 6. True binaural fittings 7. Durable

In the Ear Hearing Aids All hearing aid components fit completely in the ear CD-ROM Ch 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 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? 1. Hearing aid style 2. Level of technology

Hearing Aid Technology 1. Analog Oldest form of signal processing The signal is processed in a manner that is continuously varying over time 2. Programmable Uses analog signal processing with digital control 3. 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? 1. Hearing aid style 2. Level of technology 3. Monaural vs binaural fitting

Advantages to Binaural Amplification 1. Localization 2. Binaural summation 3. Elimination of a bad side 4. Binaural squelch 5. 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 External components Microphone Connecting cables Speech processor Transmitter CD-ROM Ch shows first body worn speech processor CD-ROM Ch is typical earlevel processor

What the Major Components Do.. Microphone Speech processor Transmitter Electrode array CD-ROM Ch illustrates what the implant looks like worn

Wireless Amplification Systems Environmental factors that make speech understanding difficult 1. Reverberation 2. Background noise CD ROM Ch and Ch illustrate typical listening conditions in a classroom

Major Types of Wireless Systems FM systems Personal FM trainers CD-ROM Ch shows an example Soundfield FM systems Infared systems Induction loop systems CD-ROM Ch audio example