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Syllabus — Hearing Aids CD 5703
Instructor: Robert de Jonge, Ph.D.
Office: Martin 58, 660-543-8809, ,
Required Text: see list at end of syllabus
Exams: There will be two exams, a mid-term and a final. Each will be multiple choice. The final will not be comprehensive. Ms. Galley will describe the assessments for the hearing aid lab.
Attendance: Class attendance policy is consistent with University policy. In addition, four absences are allowed for whatever reason (approved or not, at your discretion). Beyond this the final grade is reduced by 1/4 of a letter grade for each additional absence. The final grade will be increased by 1/4 for each of the allowed absences that is not used. Perfect attendance improves performance by one full letter grade.
The second half of the class will focus upon hearing aid measurement and selection. The main idea is to get you comfortable with the process of converting an audiogram to an appropriate hearing aid prescription, including venting, special earmolds, etc. To facilitate this we will work with a HyperCard stack, "Hearing Aid Selection," which runs on the Macintosh computer. The final exam will include a practical section where you will use this stack to fit a hypothetical client. It will help you a lot if you become familiar with this stack. There's lots of useful and practical ideas are within it. Consider it a "reading assignment." The hearing aid lab will also include a practical assessment.
Topics (a wish list)
1. Introduction/Overview
1.1 Overview of major issues involving amplification
1.2 History of hearing aids
1.3 Federal Regulations & state licensure
1.4 Types of hearing aids
-body -in-the-ear (ITE) -canal (ITC) -completely in-the-canal (CIC)
-CROS -eyeglass -behind-the-ear (BTE)
1.5 Components/functions/controls of hearing aids
-microphone -amplifier -receiver
-gain control -tone control -SSPL control
-noise suppression -telecoil -battery types
-compression, AGC -feedback -analog/digital programmables -multiband, channels -memories -remote controls
-programming software
1.6 Troubleshooting/routine maintenance
1.7 Taking an earmold impression
2. Measuring hearing aid performance
2.1 Test equipment
2.2 HA-1 and HA-2 couplers
2.3 Specification of hearing aid characteristics:
(ANSI S3.22-1982, 1987, 1996 or ASA STD 7-1982, 1987, 1996)
-OSPL90 -HF-ave OSPL90 -HF-ave full-on gain
-Full-on gain -reference test gain -frequency response
-equivalent input noise level -harmonic distortion
-battery current -induction coil -AGC aids
-chart paper
2.4 Real-ear measures of hearing aid performance (ANSI S3.46-1997):
-REUG, REIG, REAG, RESR, RECD, REDD, etc.
3. Hearing aid coupling/acoustics
3.1 Receiver characteristics
3.2 Earhook
-damping
3.3 Tubing
-length/diameter -damping -smoothing the response
3.4 Venting earmolds
-parallel/side branch -open mold
-length/diameter -damping
-PVV/SAV -insertion depth -vent response
-feedback control (Macrae)
3.5 Stepped diameter earmolds
-effects of diameter -damper placement
-Libby horn -belled -high freq cavity
3.6 Real ear effects
-KEMAR, probe-mic measurements -sound field-to-eardrum transform
-Zwislocki vs. 2-cc coupler gain -in-situ vs. insertion (etymotic) gain
-middle ear effects, middle ear pressure -microphone placement, baffle effects
-effects of varying ear canal dimensions -modeling hearing aid performance
-venting large canals (resonance effects) -Fry's test box (Fonix 6500)
4. Hearing aid selection/evaluation
4.1 Candidacy for a hearing aid
-degree of loss -speech recognition ability
-tolerance problems -unilateral losses -subjective characteristics
4.2 Preselection process
-ear(s) to fit -type of aid -specifications (gain,etc.) -coupling
4.3 Selective amplification
-Mirroring the audiogram -Master hearing aid
-Gain equal to a proportion of hearing loss -Harvard report
-Mirroring the MCL curve -MCL and LDL measurements -Bisecting the dynamic range -Effects on speech recognition
-Software (IHAFF, DSL, Fig6, HAS)
4.4 Hearing aid evaluation
-Carhart (1946) method -Measuring functional gain
-Tournament strategies -Real-ear measures
4.5 Reliability/validity of selection/evaluation process
-reliability of speech testing -problems with measuring functional gain
5. Binaural amplification
5.1 Advantages of binaural amplification
-objective benefits -subjective evaluation
5.2 Reported disadvantages
5.3 Candidacy
5.4 Selection and evaluation
5.5 Dichotic, split band amplification
5.6 Varieties of CROS hearing aids
6. Management
6.1 Counseling
6.2 Follow-up
6.3 Adjustment
6.4 Measures of user satisfaction (eg., APHAB, COSI)
Assignments
•The hearing aid lab will meet for approximately 2 hours per week. You will be able to document skills you have developed.
Readings
Pluvinage, V., "Rationale and development of the ReSound system," in Understanding Digitally Programmable Hearing Aids, R. Sandlin (ed.), 1994.
de Jonge, R., "Hearing aid evaluation and selection: A perspective," Corti's Organ, Fall newsletter of the American Auditory Society, 1989.
"Hearing Aids: Standards, Options, and Limitations," Michael Valente (ed), Thieme, 1996.
•Chap 6, Valente, Valente, Potts, and Lybarger, "Options: Earhooks, Tubing, and Earmolds."
"Strategies for Selecting and Verifying Hearing Aid Fittings," Michael Valente (ed), Thieme, 1994.
•Chap 9, de Jonge, "Selecting and verifying hearing aid fittings for symmetrical hearing loss."
"Probe Microphone Measurements: Hearing Aid Selection and Assessment," H. Gustav Mueller, David B. Hawkins, Jerry L. Northern, Singular Publishing Group, 1992.
•Chap 3, Mueller, "Terminology and procedures."
•Chap 5, Hawkins, "Prescriptive approaches to selection of gain and frequency response."
•Chap 6, Mueller, "Insertion gain measurements."
•Chap 7, Hawkins, "Selecting SSPL90 using probe-microphone measurements."
•Chap 13, Hawkins & Mueller, "Test protocols for probe-microphone measurements."
"Handbook of Hearing Aid Amplification, Volume I and II," Robert E. Sandlin (ed), College Hill Press, 1988.
Volume I
•Chap 1, Lybarger, "A historical overview."
•Chap 5, Dillon, Compression in hearing aids."
√Chap 7, Libby & Westermann, "Principles of acoustic measurement and ear canal resonances." (Scan for exposure to info)
Volume II
•Chap 1, Reiter, "Psychology of the hearing impaired and hearing aid use: The art of dispensing."
•Chap 3, Pascoe, "Post-fitting and rehabilitative management of the adult hearing aid user."
"Hearing Aid Evaluation," Margaret W. Skinner, Prentice Hall, 1988.
•Chap 2, "Effects of hearing impairment on the identification of speech sounds."
•Chap 10, "Counseling and hearing aid orientation."
"Amplification for the Hearing-Impaired," 3rd Edition, Michael C. Pollack (ed.), 1988.
•Chap 2, Pollack, "Electroacoustic characteristics."
•Chap 11, Glaser & Pollack, "Private practice and hearing aid dispensing."
Assignments for mid-term
1. Introduction/Overview
•Pollack, Chap 2, 3 (p. 105-114, impression technique), 11
•Sandlin, Volume I, Chap 1
•Sandlin, Volume II, Chap 1
•Skinner, Chap 2
•Hearing aid selection and evaluation: A perspective.
Assignments for final
2. Measuring hearing aid performance
•User's manual for the Fonix hearing aid test system.
•Sandlin, Volume I, Chap 5, 7
3. Hearing aid coupling/acoustics.
•Valente, et al. Chap 6 (p. 252-326)
4. Hearing aid selection/evaluation.
•Mueller et al., Chap 3, 5, 6, 7, 13
•HyperCard stack: Hearing Aid Selection.
5. Binaural amplification.
•Valente, Chap 9.
6. Management.
•Skinner, Chap 10.
•Sandlin, Volume II, Chap 3
7. Programmable hearing aids
•Pluvinage