Behavioral Testing; Hearing Aid Selection and Fitting AG Bell/MUSC OTO-HNS Conference October 18, 2013

Transcription

1 Behavioral Testing; Hearing Aid Selection and Fitting AG Bell/MUSC OTO-HNS Conference October 18, 2013 Kimberly Astrid Orr, Au.D., CCC-A Director of Audiology Medical University of South Carolina Department of Otolaryngology, Head and Neck Surgery Charleston, S.C.

2 What is a Behavioral Test? A test requiring the participant to reliably demonstrate a change in behavior when a sound is heard. Goal is to determine the lowest (softest) intensity level (threshold) at which a child can detect a sound at specific frequencies. Techniques utilized in behavioral testing are selected based upon the child s developmental level.

3 Behavioral Test Techniques Behavioral Observation Audiometry (BOA) Used when testing infants 5 months of age or for those functioning at a developmental age of 5 months. Not used for diagnosis of hearing loss. Unconditioned responses consist of startle, eye widening, sucking or cessation of sucking, etc. Results can be examiner biased. Levels reported are minimum response levels.

4 Visual Reinforcement Audiometry (VRA) Technique used to obtain behavioral audiometric thresholds from children who function at at 6 month through 30 month old developmental level. Operant conditioning task in which the child is trained to look for an auditory stimulus and is reinforced with flashing lights/animated toy. Can be used in sound field, under headphones, with insert earphones or bone oscillator. Results should correlate with ABR predicted thresholds.

5 VRA Demo

6 Conditioned Play Audiometry (CPA) Used to obtain behavioral thresholds from children who function at the 2.5 through 5 year old developmental level. Child is engaged in a play-oriented activity and trained to perform a task such as stacking rings, dropping blocks, placing pegs etc, in response to an auditory stimuli. Testing performed under headphones, insert earphones, in sound field or through bone oscillator. Speech awareness testing may also be completed using this method. Language is never a barrier, as there are no verbal directions. Degree of hearing loss should not be an issue. If child does not respond, attempt conditioning using vibrotactile stimulation.

7 Conventional Hand Raising Method used to establish pure-tone thresholds from children who have a developmental age of 5 years of age. Can be less engaging to those < 7 years, so if fatigue or reliability is an issue, try implementing CPA techniques. Remember.just because a child can raise their hand in response to a stimulus like an adult, they are NOT adults. Children require consistent and positive feedback during testing.

8 Speech Audiometry For infants developmental age of 2 years, speech awareness thresholds (SAT) can be obtained via air and bone conduction stimuli. SAT is often obtained at slightly lower thresholds (5-10 db) than frequency specific pure tone thresholds, as speech stimuli can be more interesting and meaningful to a child.

9 Speech Audiometry Continued Speech reception thresholds (SRT) can be obtained from young children by having them point to body parts or spondees on a picture board, after they have been familiarized to the test stimuli. SRT can be obtained via air or bone conduction transducers. Word recognition scores (WRS) is not usually attempted until at least a developmental age of 3 years. If pictures are used, child must know the vocabulary. If task is to repeat words orally, articulation must be good. It is far more important to obtain accurate pure tone thresholds prior to attempting word recognition testing.

10 Physiological Test Components Acoustic Immitance Tympanometry and acoustic reflex thresholds are most common. Used to assess middle ear function. Used to evaluate acoustic reflex pathways, which include cranial nerves VII and VIII and the auditory brainstem. Is the measurement of energy or air pressure flow, which involves the ear canal, eardrum, ossicular chain, tensor tympani, stapedius muscle, cochlea, CNs VII and VIII and the brainstem.

11 Physiological Test Components Otoacoustic Emissions (OAEs) OAEs are low-level sounds generated by the outer hair cells of the cochlea in response to auditory stimuli. Present in nearly all normal hearing ears. Absent in ears with hearing loss and/or middle ear pathology. OAEs are often PRESENT in infants with auditory neuropathy/dyssynchrony.

12 Auditory Brainstem Response Neurologic test of auditory function in response to auditory stimuli. It is an evoked potential generated by a brief click or tone transmitted from an acoustic transducer. It is measured via surface electrodes (one on forehead and one on each mastoid). Produces identifiable waveforms plotted in amplitude (microvolts) versus time (milliseconds) Waveform components include waves I, II, III, IV and V. V is most commonly analyzed in clinical applications of ABR. Used to provide information regarding auditory function and hearing sensitivity. Should be used in conjunction with behavioral audiometry, if possible.

13 Types of Hearing Loss Conductive (CHL) Occurs when sound is not conducted efficiently through the outer ear canal to the tympanic membrane and the ossicles of the middle ear. Hearing loss can often be medically or surgically corrected. Examples: fluid/infection in the middle ear, poor eustachian tube function, perforation of the TM, tumor in outer or middle ear (cholesteatoma), impacted cerumen, presence of foreign body, microtia or atresia, ossicular fixation or malformation.

14 Types of Hearing Loss Continued Sensorineural (SNHL) Occurs when there is damage to the cochlea or to the VIII nerve pathways or from the inner ear (retrocochlear) to the brain. Cannot be medically or surgically corrected. Permanent, but not necessarily stable. In addition to making sounds appear soft, SNHL also affects both speech understanding or the ability to hear clearly. Can be caused by: birth injury, ototoxic drugs, genetic syndromes, diseases, noise exposure, viruses, head trauma, aging, tumors and congenital malformations.

15 Types of Hearing Loss Continued Mixed Combination of CHL and SNHL. Transient CHL issues are treated more aggressively in children with underlying SNHL.

16 Types of Hearing Loss Continued Auditory Neuropathy Spectrum Disorder (ANSD) Disorder characterized by evidence of normal cochlear outer hair cell function and abnormal auditory nerve function Children should be fit with amplification when reliable, stable hearing thresholds are determined. Children should be considered for cochlear implantation if not making progress in language development regardless of behavioral pure-tone thresholds.

17 Degrees of Hearing Loss

18 Diagnosis of Hearing Loss Referral to ENT for Otologic workup Offer referal for genetics Offer referral for opthalmology Referral to speech pathology Possible referral for developmental evaluation Referral to Babynet for Early Intervention services for those from 0 months to 30 months Referral to public schools for 31 months to 5 years

19 Habilitation/Rehabilitation Hearing aids Fit only after comprehensive medical evaluation and workup. Medical clearance is required by FDA for those less than 18. Behind-The-Ear Bone conduction, including BAHA Early intervention Babynet SCSDB Beginnings Speech therapy AVT

20 Candidacy for Amplification Children with aidable unilateral hearing loss, including good WRS in affected ear. Children with severe/profound unilateral hearing loss (CROS or bone conduction devices can be considered, not traditional HA). Children with minimal or mild sensorineural hearing loss. Children with ANSD who have reliable, behavioral audiograms consistent with hearing loss. Children with permanent conductive hearing loss. Children considered for cochlear implantation should have a trial with amplification prior to CI surgery.

21 Hearing Aid Considerations Good quality amplification which when programmed appropriately allows for maximized audition while keeping amplified sounds comfortable and safe for the user. Flexible in programming to accommodate fluctuating or progressive hearing loss. Compatible with direct audio input. Durable units with moisture protection and locking mechanisms.

22 Signal Processing and Features Compression: input levels should be compressed sufficiently to accommodate sensitivity to loud sounds while allowing low level speech audibility. Channels: number of software channels/bands that can be manipulated for sufficient frequency shaping to meet the needs of the audiometric configuration. Frequency compression: compresses selected high frequency sounds into a lower frequency range where both hearing sensitivity and discrimination ability are better. Feedback suppression Directional microphones Digital noise reduction circuitry

23 Verification Measures Use of evidence based prescriptive methods: typically DSL (Desired Sensation Level) for children. For children, there are two options 1. Real-ear aided probe microphone measurements: output of the hearing aid is measured in the child s ear at a variety of input levels, including speech-like stimuli and maximum power output. 2. Simulated real-ear aided response measurements in the coupler using measured or age-appropriate real-ear to coupler difference (RECD) using a variety of input levels, including speech-like stimuli and maximum power output.

24 Functional Gain Aided thresholds determined in the sound field while the child is wearing the hearing aids, compared to the unaided thresholds. Word recognition testing in the presence of speech noise is often utilized. Provides helpful information regarding frequency transposition /compression hearing aids. Potential errors secondary to interaction with input stimulus and hearing aid signal processing. Parents, teachers and therapists value the aided audiogram. Audiologists should use these in addition to verification measures.

25 Management and Follow-up Hearing impaired children require on-going audiologic evaluation and management/adjustment of amplification to ensure consistent audibility over time. Managing audiologist should ensure proper medical referrals. Managing audiologist should ensure proper referrals to early intervention and schools. Managing audiologist should provide resources for financial support and funding to aid in offset of amplification fees. Managing audiologist should offer parent-to-parent support for families and caregivers with hearing impaired children.

26 Team Approach The diagnosis and management of hearing loss in children in an ongoing and collaborative effort among the otolaryngologist, audiologist, primary care physician, educational personnel/early interventionist, speechlanguage pathologist and the family.

27 The End