Hearing aids / Harvey Dillon.

Previous ed.: 2000.

Includes bibliographical references and index.

POGO--NAL--DSL--Examples and comparisons: POGO II, NAL-RP and DSL-- Difficult issues in prescription--Acclimatization and adaptation to gain and frequency response--Preferred loudness--Dead regions--Severe hearing loss, effective audibility and high-frequency amplification--Prescribing compression thresholds--Need for accuracy in prescription--Gain, Frequency response, and input-output functions for non-linear amplification--LGOB--IHAFF/Contour--ScalAdapt--FIG6--DSL(i/0) and DSLm(i/0)--NAL-NL1 and NAL-NL2--CAMREST, CAMEQ and CAMEQ2-HF--Compassion of procedures--Allowing for conductive and mixed hearing losses--Selecting options for multi-memory hearing aids--Music programs--Candidates for multi-memory hearing aids--Prescribing OSPL90--General principles: avoiding discomfort, damage and distortion--Type of limiting: compression or peak clipping--OSPL90 prescription procedures--Prescribing OSPL90 at different frequencies--OSPL90 for non-linear hearing aids--OSPL90 for conductive and mixed losses--Excessive amplification and subsequent hearing loss-- Concluding comments--11. SELECTING, ADJUSTING AND VERIFYING HEARING AIDS:- Selecting hearing aid style: CIC, ITC, ITE, BTE,Spectacle aid, or body aid--Selecting hearing aid features--Hearing aid selection and adjustment--Allowing for individual ear size and shape in the coupler prescription--Verifying and achieving the prescribed real-ear response--Verifying signal processing features--Evaluating and fine-tuning OSPL90 --Concluding comments--12. PROBLEM SOLVING AND FINE-TUNING:- Solving common problems--Management difficulties--Earmold or earshell discomfort--Poor earmold or earshell retention--Own voice quality and occlusion--Feedback oscillation--Tonal quality--Noise, clarity, and loudness--Systematic fine-tuning procedures--Paired comparisons--Absolute rating of sound quality--Systematic selection by paired comparisons--Adaptive parameter adjustment by paired comparisons--Adaptive fine-tuning by absolute rating of quality--Fine-tuning at home with multi-memory or trainable hearing aids--Concluding comments: Fine-tuning in perspective--13. PATIENT EDUCATION AND COUNSELING FOR HEARING AID WEARERS:- Understanding hearing loss--Acquiring a hearing aid--Using hearing aids--Adjusting to new experiences with sound and hearing aids--Care of hearing aids--Hearing strategies--Observing the talker and surroundings--Manipulating social interactions-- Manipulating the environment--Teaching hearing strategies--Involving families and friends--Auditory training--Computer-based auditory training at home--Avoiding hearing aid-induced hearing loss--Assistive listening devices--Counseling support--Interacting with different personality styles--Structuring appointments--The assessment appointment(s)--The fitting appointment(s) --The follow-up appointment(s)--The power of groups--Concluding comments--14. ASSESSING THE OUTCOMES OF HEARING REHABILITATION:- Outcome domains--Speech understanding tests--Limitations of speech tests to assess benefits--Role of speech testing in evaluating benefit--Self-report questionnaires for assessing benefit--Questionnaire methodology--Practical self-report measures--Meeting needs and goals--Assessing usage, problems, and satisfaction--The International outcomes innventory for hearing aids (IOI-HA)--Changes in outcomes with time after fitting--Impact of hearing loss and hearing aids on health-related quality of life--Effect of hearing loss on health-related quality of life--Effect of hearing aids on health-related quality of life--Concluding comments--15. BINAURAL AND BILATERAL CONSIDERATIONS IN HEARING AID FITTING:- Binaural effects in Localization--Localization cues in normal hearing--Effects of hearing loss on localization--Binaural effects in detection and recognition--Dead diffraction effects--Binaural squelch in noise--Binaural redundancy--Binaural loudness summation--Advantages of bilateral fittings--Speech intelligibility--Localization--Sound quality--Avoiding late-onset auditory deprivation--Suppression of tinnitus--Miscellaneous advantages--Disadvantages of bilateral fittings--Cost--Binaural interference--Self-image--Miscellaneous disadvantages--Tests of bilateral advantage--Bias in choosing the reference ear for the inilateral condition--The sensitivity of speech tests for assessing bilateral advantage--Role for speech tests in assessing bilateral advantage--Localization test--Fitting asymmetrical hearing losses--Bilateral versus unilateral fittings for asymmetrical losses--Better ear versus poorer ear for unilateral fittings--Alternatives: FM and CROS-- Deciding on bilateral versus unilateral fittings--Effect of bilateral versus unilateral fitting on electroacoustic prescriptions--Concluding comments--16. SPECIAL HEARING AND ISSUES FOR CHILDREN:- Sensory experience, sensory deprivation, and candidacy for hearing aids--Binaural stimulation--Unilateral loss--Slight and mild hearing loss--Cochlear implantation--Auditory neuropathy spectrum disorder--Assessment of hearing loss--Frequency-specific and ear-specific assessment--Small ears and calibration issues--Auditory processing disorders--Miscellaneous issues in assessment--Hearing aid and earmold styles--Hearing aid style--Earmolds--Prescribing amplification for children--Speech identification ability and amplification requirements--Threshold-based versus loudness-based procedures--Allowing for small ear canals--Signal processing features--Assistive listening devices (ALDs)--Verifying real-ear performance--Evaluating aided performance--Speech tests--Paired- comparison tests--Evaluation of discomfort--Subjective report measures--Articulation index or speech intelligibility index (SII)--Evoked cortical responses--Speech production and language acquisition--Helping parents--Hearing habilitation goals--Goals and strategies for infants--Goals and strategies for toddlers--Goals and strategies for pre-schoolers--Goals and strategies for primary school children--Teenagers and cosmetic concerns--Safety issues--Concluding comments--17. CROS, BONE-CONDUCTION, AND IMPLANTED HEARING AIDS:- CROS hearing aids--Simple CROS aids--Vilateral CCROS (BICROS) aids--Stereo CROS (CRIS-CROS)aids--Transcranial CROS aids--Bone-conduction Hearing aids--Applications of bone-conduction hearing aids--Bone-conduction hearing aid output capabilities--Prescribing, adjusting and verifying electrocoustic characteristics for bone-conduction hearing aids--Disadvantages of bone-conduction hearing aids--Bone-anchored hearing aids--BAHAs for unilateral conductive or mixed hearing loss--Bilateral BAHAs for bilateral conductive or mixed hearing loss--BAHAs for single-sided sensorineural deafness--Complications with BAHAs--Middle-ear implantable hearing aids--Output transducers--Microphones--Complete systems--Candidacy and benefits--Complications with middle-ear implants--Concluding comments.

1. INTRODUCTORY CONCEPTS:- Problems faced by people with hearing impairment--Decreased audibility--Decreased dynamic range--Decreased frequency resolution--Decreased temporal resolution--Physiological origins of hearing loss--Deficits in combination--Acoustic measurements:- Basic physical measures--Linear amplifiers and gain--Saturation sound pressure level- couplers and real ears--Types of hearing aids--Historical perspective--The acoustic era--The carbon era--The vacuum tube era--The transistor and integrated circuit era--The digital era--The wireless era--2. HEARING AID COMPONENTS:- Block diagrams--Microphones--Principle of operation-- Frequency response of microphones--Microphone imperfections--Directional microphones--microphone location--Amplifiers:- Amplifier technology--Peak clipping and distortion--Compression amplifiers--Digital circuits:-Analog-to-digital converts--Digital signal processors--Hard-wired digital processing--General arithmetic digital processing--Sequential processing,block processing, and hearing aid delay--Digital-to-analog converters--Specifications for digital hearing aids--Digital versus analog hearing aids--Filters, tone controls and filter structures--Filters--Tone controls--Filter structures--Receivers:- Principle of operation--Frequency response of receivers--Acoustic Dampers:- Telecoils--Audio (Electrical) input--Remote controls--Bone conductors--Batteries:- Principle of operation--O perating voltage--Capacity and physical size--Rechargeable batteries--Concluding comments-- 3.HEARING AID SYSTEMS:- Custom and Modular Construction--Custom hearing aids--Modular hearing aids--Semi-modular, semi-custom hearing aids--Hearing aid reliability--Linked bilateral hearing aids--Programming the hearing aid--Programmers, interfaces, and software--Multi-memory or multi-program hearing aids--Paired comparisons--Remote sensing and transmitting hearing aid systems--Induction loops--Field uniformity and direction--Magnetic field strength--Loop frequency response--Radio-frequency transmission--Frequency modulation--Digital modulation techniques--Coupling to the hearing aid--Combining wireless and local microphones--Infra-red transmission--Classroom sound-field amplification--Comparative strengths and weaknesses of magnetic loops, radio-frequency wireless systems, infra-red, and sound-field amplification systems--Assistive listening devices--Connectivity and convergence--Connecting electronic devices to hearing aids--Convergence--Interference between mobile phones and hearing aids--Concluding comments -- 4. ELECTROACOUSTIC PERFORMANCE AND MEASUREMENT:- Measuring Hearing aids in couplers and ear simulators--Couplers and ear simulators--Test boxes--Measurement signals--Gain-frequency response and OSPL90-frequency response--Input-Output functions--Distortion--Internal noise--Magnetic response--ANSI,ISO and IEC standards-- Real ear to coupler-difference (RECD)--Factors affecting RECD--Measurement of RECD--RECD and REDD--Real-ear aided gain (REAG)--Positioning the probe for REAG measurement--Relationship between REAG, coupler gain and ear simulator gain--Detecting incorrect aided measurements--Insertion gain--Positioning the probe for insertion gain measurement--Relationship between insertion gain, coupler gain and ear simulator gain--Detecting incorrect insertion gain measurements--Accuracy of insertion gain measurements--Practical issues in Real-Ear testing--Probe calibration--Control microphones---Effects of wax--Contamination by background noise--Hearing aid saturation--Loudspeaker orientation--Measurement signal characteristics--Aided threshold testing and functional gain--Feedback in hearing aids--The feedback mechanism--Effects of feedback on sound quality--Probe-tube measurements and feedback--Troubleshooting faulty hearing aids--Concluding comments-- 5. HEARING AND EARMOLDS,EARSHELLS AND COUPLING SYSTEMS:- Earmold, earshell and canal fitting physical styles--BTE earmold styles--ITE, ITC and CIC

earshell styles--Overview of earmold, eaarshell and canal fitting acoustics--Venting--Effects of vents on hearing aid gain and OSPL90--Venting and the occlusion effect--Effects of vents and leaks on feedback oscillations--Interaction of vents with digital signal processing algorithms--Parallel versus Y (or diagonal) vents--Open-canal fittings in summary--The sound bore: tubing, horns and constrictions--Acoustic horns and constrictions--Tubing insertion depth--Dampers--Specific tubing, damping and venting configurations--Procedure for selecting earmold and earshell acoustics--Ear impressions--Standard ear impression techniques--Ear impression techniques for CICs and high-gain hearing aids--Ear impression materials--Earmolds and earshells--Earmold and earshell construction--Materials for earmolds and earshells--Instant earmolds and hearing aids-- Modifying and repairing earmolds and earshells--Concluding comments--6. COMPRESSION SYSTEMS IN HEARING AIDS:- Compression\'s major role: reducing the signal\'s dynamic range--Basic characteristics of a compressor--Dynamic compression characteristics: attack and release times--Static compression characteristics--Input and output control--Multichannel compression--Rationales for use of compression--Avoiding discomfort, distortion and damage--Reducing inter-syllabic and inter-phonemic intensity differences--Reducing differences in long-term level--Increasing sound comfort--Normalizing loudness--Maximizing intelligibility--Reducing noise--Empirical approaches--Combinations of compressors in hearing aids--Benefits and disadvantages of different compression systems--Compression relative to linear amplification--The benefits of multichannel relative to single-channel compression--Slow versus fast compression--Concluding comments--7. DIRECTIONAL MICROPHONES AND ARRAYS:- Directional microphone technology--First-order subtractive directional microphones--Additive directional arrays--Complex directional arrays--Bilateral directivity--Quantifying directivity--2D and 3D directivity index--AI-DI--Directional benefit--Impact of listening environment--Objective benefit in the clinic and self reported benefit in real life--Interaction of directivity with other technologies--Disadvantages of directivity--Candidates for directional microphones--Evaluation of directional microphones in the clinic--Concluding comments--8. ADVANCED SIGNAL PROCESSING SCHEMES:- Adaptive noise reduction--Adaptive noise reduction technology--Adaptive noise reduction benefits--Impulse noise reduction--Feedback reduction--Feedback reduction by gain-frequency response control--Feedback reduction by phase control--Feedback reduction by feedback path cancellation--Feedback reduction by frequency shifting--Feedback reduction systems in combination--Frequency lowering --Frequency lowering rules--Frequency lowering techniques--Commercially available frequency lowering schemes--Fequency lowering, speech intelligibility and candidacy--Speech cue enhancement--Other signal processing schemes--Concluding comments--9. ASSESSING CANDIDACY FOR HEARING AIDS:- Factors affecting the lower limit of aidable hearing loss--Attitude and motivation--Pure tone loss and audiogram configuration--Speech identification ability--Self reported disability--Acceptance of noise--Listening environment, needs and expectations--Stigma and cosmetic concerns--Manifulation and management--Age--Personality--Central auditory processing disorders--Tinnitus--Factors in combination--Counseling the unwilling patient: some examples--The Upper Limit of Aidable hearing loss--Poor speech identification ability--Hearing aids or cochlear implants?--Hearing aids and cochlear implants: bimodal and hybrid / electroacoustic stimulation---Hearing aids or tactile aids?--Medically related contra-indications to hearing aid fitting-- Concluding comments--10. PRESCRIBING HEARING AID AMPLIFICATION:- General concepts behind a Prescriptive approach and brief history--Gain and frequency response prescription for linear amplification--

This title is completely revised to reflect the research and technological advances of the last decade. It features new chapters on directional microphones and the latest digital signal processing strategies, and includes extensive coverage of all aspects of open-canal, thin-tube hearing aids.