Hearing Impairment and Audiological Foundations
Audiological basics
Know the types of hearing loss: conductive (outer/middle ear), sensorineural (cochlea/auditory nerve), and mixed. Understand pure-tone audiometry (air vs. bone conduction), speech audiometry (SRT, WRS), tympanometry, and otoacoustic emissions. Know the degree classifications: mild (26–40 dB), moderate (41–55), moderately severe (56–70), severe (71–90), profound (>90). Understand that bone conduction better than air conduction indicates conductive loss; both equal indicates sensorineural.
Impact on speech and language
Know that hearing loss affects speech perception, phonological development, and vocabulary. Early identification (newborn screening) and amplification (hearing aids, cochlear implants) improve outcomes. Understand the role of the speech-language pathologist in auditory training, speech perception, and language intervention.
Traps in questions
A common trap is confusing air and bone conduction results. Another is assuming a child with a cochlear implant needs no language therapy-they still do. Do not confuse tympanometry (middle-ear status) with audiometry (hearing thresholds). Remember that unilateral loss can still affect classroom listening and localization.
Rule of thumb
Air worse than bone → conductive. Air equals bone → sensorineural. Both abnormal with a gap → mixed.
Worked example: Air thresholds at 40 dB and bone at 10 dB across frequencies → conductive hearing loss, likely middle-ear effusion.