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Direct answers to specific audiology questions, one page per question.
Prevention
Newborn hearing screening and the JCIH timeline
The Joint Committee on Infant Hearing's 1-3-6 timeline calls for screening by 1 month, diagnostic evaluation by 3 months for anyone who does not pass, and enrollment in early intervention by 6 months for anyone diagnosed with hearing loss. JCIH's 2019 statement kept 1-3-6 as the benchmark but added a 1-2-3 goal, moving diagnosis to 2 months and intervention to 3 months.
NIOSH vs OSHA noise exposure limits
NIOSH vs OSHA: OSHA PEL 90 dBA 8-hour TWA, 85 dBA action level, 5 dB exchange. NIOSH: 85 dBA and 3 dB exchange. At 95 dBA, OSHA 4 hours; NIOSH about 47 minutes.
Assessment
ABR waves I, III, and V: latencies and what shifts them
At a high click level, normal adult latencies are roughly wave I at 1.6 to 1.65 ms, wave III at 3.7 to 3.8 ms, and wave V at 5.5 to 5.65 ms, with an I to V interpeak interval near 4 ms. A conductive loss delays every wave equally, leaving interpeak intervals normal, while a retrocochlear lesion delays wave III and V and prolongs the interpeak intervals themselves.
Acoustic reflex thresholds and the four-box patterns
Normal contralateral acoustic reflex thresholds run roughly 75 to 95 dB HL at 500 to 2000 Hz, about 2 to 5 dB lower for ipsilateral, and broadband noise thresholds sit about 20 dB lower than tonal ones. The four boxes, probe right, probe left, each with ipsilateral and contralateral stimulation, form vertical, diagonal, or horizontal patterns of absence that localize conductive, cochlear, eighth nerve, and brainstem lesions.
Dix-Hallpike BPPV test: findings by canal
Dix-Hallpike BPPV by canal: posterior upbeating torsional nystagmus to the affected ear, fading in a minute. Anterior downbeating. Horizontal: supine roll test.
How to read an audiogram: symbols, degree, and PTA
Circles and X's mark unmasked air conduction, carets mark bone conduction, and triangles and squares mark masked air conduction, in red for the right ear and blue for the left. Degree of loss is read off the pure-tone average using a named scale such as Clark, and a loss spanning more than one category is described as a range, such as mild sloping to severe, not a single label.
Interaural attenuation values for clinical masking
Use the minimum of the reported range so cross-hearing is never missed: 40 dB for supra-aural earphones, 55 dB for insert earphones, and 0 dB for bone conduction. Insert earphones buy the most headroom because they contact far less of the skull than a supra-aural cushion, which is why they resolve so many masking impasses.
SRT vs WRS: speech reception and word recognition
SRT vs WRS: SRT is 50 percent spondee ID and should match PTA within 5 to 10 dB. WRS is percent-correct at a suprathreshold level (clarity, not sensitivity).
Tympanogram types A, As, Ad, B, and C explained
Tympanogram types: A normal peak; As shallow (stiff/otosclerosis); Ad tall (discontinuity); B flat; C negative-pressure peak (eustachian tube dysfunction).
Intervention
Adult cochlear implant candidacy criteria
Adult cochlear implant candidacy generally requires moderate to profound sensorineural hearing loss and limited benefit from well-fitted hearing aids, most often shown as poor sentence or word recognition in the best-aided condition. FDA labeling has broadened to include less severe losses than it once did, but exact cutoffs vary by device and insurer, so confirm current labeling rather than treating any one number as fixed.
REM verification: real-ear measurement and targets
REM verification confirms hearing-aid output at the eardrum for soft to loud speech. A NAL-NL2 or DSL target within 5 dB matches the prescription.