CSD 3000DEAFNESS IN SOCIETY

Topic 8HEARING AIDS AND ASSISTIVE

TECHNOLOGY

Modern Hearing Aid Design

MiniturizationEnhanced signal processing

Multiple memories Noise reduction Feedback control Programmability Digital processing Multiple channels

Important Hearing Aid Components

1. BatteriesSizes and materials

2. MicrophonesDirectional and omnidirectional

3. Amplifiers4. Receivers

External air conduction, bone conduction, vibrotactile

Other Optional Features

1. On/off switch2. Telecoil

Separate circuit to use with a telephone receiver or an induction loop system

Reduces feedback and improves interference from background noise

3. Volume Control4. 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?

1. Hearing aid style

Major Hearing Aid Styles

1. Body hearing aids2. Eyeglass hearing aids3. Behind the ear hearing aids4. In the ear hearing aids5. 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

aidReceiver is externalNeeds an earmold

AdvantagesHigh gain, no feedback, large controls

DisadvantagesStigma, monaural fittings only,microphone placement

Eyeglass styleAll 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

1. Flexibility2. Good choice for kids3. Compatibility with direct audio input4. Good feedback control5. Microphone placement6. True binaural fittings7. Durable

In the Ear Hearing Aids

All hearing aid components fit completely in the ear

CD-ROM Ch.07.05Biggest 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

DisadvantageSize demands

Hearing Aid Fitting Considerations

What does the audiologist consider when making the recommendation for amplification?

1. Hearing aid style2. 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 style2. Level of technology3. Monaural vs binaural fitting

Advantages to Binaural Amplification

1. Localization2. Binaural summation3. Elimination of a bad side4. Binaural squelch5. 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 ImplantsInternal 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..

MicrophoneSpeech processorTransmitterElectrode arrayCD-ROM Ch.07.11 illustrates what

the implant looks like worn

Wireless Amplification Systems

Environmental factors that make speech understanding difficult

1. Reverberation2. 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 systemsInduction loop systemsCD-ROM Ch.07.13 audio example