Recommended Protocol for Audiological Assessment, Hearing Aid Evaluation, and Cochlear Implant Monitoring

Copyright 2003 Auditory-Verbal International, Inc.

The following protocol is intended to support programs for early detection of hearing impairment, which should include medical evaluation/clearance for hearing aid use for infants and children. It is also a guide to appropriate ongoing audiology services in Auditory-Verbal Therapy programs. Auditory-Verbal International, Inc. recommends this audiological protocol in order to achieve and maintain optimal use of residual hearing to access spoken language. The test battery approach to audiological assessment is well recognized and is recommended in this protocol. This means that no single test should be used in isolation to define and describe the nature and extent of a hearing loss. Ideally, every Auditory-Verbal program will have on-site audiological services, but, regardless of setting, close collaboration of audiologists, therapists, and parents is essential. Parents should be present and participate in all assessments as well as in Auditory-Verbal Therapy sessions. The Auditory-Verbal therapist should also be present at audiological assessments whenever possible or send a report identifying his/her questions or concerns regarding the child’s hearing and amplification.

    Procedures to be included in all assessments regardless of child’s age:

    • Medical/Developmental History

    • Parent Observation Report

    • Otoscopic Inspection

    • Acoustic Immittance including tympanometry with high frequency probe tone and acoustic reflex tests

    Audiological Diagnostic Assessment:

    I. Auditory Brainstem Response (ABR) Assessment

      a. Threshold search to click stimulus in 10dB steps with a 0dB (no stimulus) comparison

      b. Comparison of ABR by rarefaction clicks and condensation clicks presented at 80-90dBnHL using a click rate > 30/second to rule out auditory neuropath

      c. Threshold search to a 500 Hz and 3000 Hz tone pip

      d. Bone conduction ABR using click stimuli

    ABR should not stand alone for diagnostic purposes. Absence of a detectable ABR does not necessarily indicate an absence of usable residual hearing. Special imaging (CT scan and or MRI) may be required to rule out absence or abnormality of the cochlear structures, such as a Mondini Dysplasia or Enlarged Vestibular Aqueduct.

    II. Otoacoustic emissions (TEOAE and/or DPOAE).

    III. Behavioral Observation Audiometry (BOA) using speech as well as 500-2000 Hz warbled tones and/or narrowband noise, by air conduction and bone conduction to identify minimum response levels and to obtain startle response.

    IV. Evaluation of auditory skill status and tests of speech perception.

    V. Discussion of results, questions, and recommendations with parents.

    VI. Written report of all tests and results, including:

      a. Descriptions of test procedures, conditions of testing, and reliability estimate

      b. A complete audiogram with symbol key, calibration, and stimuli identified, as well as plotting results on a “Familiar Sounds” audiogram to support parent/teacher counseling

      c. Identification of hearing device, including manufacturer, model, output and response, compression or special feature settings, earmold specifications, and quality of fit

      d. Copies to parents, primary care provider, Auditory-Verbal therapist and other health/education providers as requested in writing by parents

    VII. Referral to medical, otolaryngological, or other resources (genetic counseling, social services, psychology, occupational therapy, etc.) as appropriate.

    Amplification Assessment

    I. Electro-acoustic analysis of hearing aids

      a. On day of fitting

      b. Every 30 days at user volume as well as full volume

      c. Upon return from repairs

      d. If parental concerns arise from behavioral observation or listening check

    II. Real-Ear-to-Coupler Measures (e.g. Desired Sensation Level (DSL))

      a. To establish fitting parameters for hearing aids using prescriptive methods

      b. To verify instrument settings in order to achieve target gain and output

    III. Probe Microphone Measures

      a. To document hearing aid performance at initial fitting

      b. Upon return from repairs

      c. To assess changes in earmold style

    IV. Sound Field Aided Response

      a. To demonstrate response to speech for parent education purposes

      b. To assess speech perception at average and at soft conversational levels in quiet and in the presence of noise to evaluate the effectiveness of amplification technology

      c. Assessment of distance hearing using the Ling 6 Sound Test to demonstrate the range of audibility provided by the technology

    NOTE: Functional gain measure is an appropriate verification procedure for bone conduction hearing aids, cochlear implants, and vibrotactile aids only. Verification of amplification requires a real ear to coupler (RECD) measure appropriate for children.

    Audiological Monitoring

    • Initial diagnosis and confirmation should be completed as soon as possible, but, at the latest, within the first three months of life in order to ensure that habilitation is underway by age six months.

    • Routine evaluation should occur ideally at 4-6 week intervals during the first 12-18 months of life and at 3-month intervals through age 3, although new earmolds may need to be obtained more frequently.

    • Assessment at 6-month intervals from age 4 is appropriate if progress is satisfactory.

    • Immediate evaluation should be undertaken if parent or caretaker concern is expressed or if behavioral observation by parent, therapist, or teacher expresses concern, or if behavioral observation suggests a change in hearing or device function.

      More frequent evaluation is appropriate when middle ear disease is chronic or recurrent or when risk factors for progressive hearing loss are present.

    Cochlear Implant Monitoring

    • When a child does not achieve optimal access to spoken language through conventional amplification by age 9 months, information should be provided regarding cochlear implant technology, including benefits and risks as documented in published, peer-reviewed literature along with referral to a cochlear implant center.

    • Following initial mapping of a cochlear implant, re-mapping should be conducted on the schedule recommended by the cochlear implant team given the child’s age, device implanted, number of electrodes activated, and additional individual considerations.

    • Even if a map can be programmed to achieve optimal access to the speech spectrum within the first three months of use, ongoing evaluation at six-month intervals for at least three years after initial stimulation is recommended.

    • Routine assessment of cochlear implant performance should occur at 6-12 month intervals if progress is satisfactory.

    • Immediate evaluation is recommended if parent, caregiver, and/or therapist observe behavior suggesting a change in performance or express concern regarding device function.

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