Interpretation Normal acoustic reflex threshold Elevated acoustic reflex threshold Lowered acoustic reflex threshold Absent acoustic reflex 1

Acoustic reflex results: Patterns 2

Objective tests of the auditory system Acoustic immittance measures Static acoustic compliance Tympanometry Acoustic reflex Otoacoustic emissions (OAE) Transient-evoked OAE (TEOAE) Distortion-product OAE (DPOAE) Auditory evoked potentials Electrocochleography (ECog) Auditory brainstem response (ABR) Auditory middle latency response (AMLR) Auditory late response (ALR) 3

Otoacoustic emissions Sounds generated by the cochlea and recorded in the external auditory meatus. By-product of the active non-linear cochlea. Conductive pathway must be normal for OAEs to be recorded. Types: Spontaneous (SOAE) Evoked: Distortion-product OAE (DPOAE) Transient-evoked OAE (TEOAE) 4

Occur in many normal ears Level: About 10 dB TEOAE Spontaneous OAE Occur in many normal ears Level: About 10 dB TEOAE Transient sounds like clicks or tone-bursts. Present many stimuli (260 to 500). Average responses to separate emissions from the noise floor. DPOAE Two pure tones (f1 and f2) that vary in frequency. Cochlea produces additional tones called distortion products. Does not require as many stimulus repetitions and averaging as TEOAE 5