same side

measuring probe and stimulus are in the same ear

opposite side

measuring probe and stimulus are in opposite ears

• Acoustic reflex threshold = lowest level at which the acoustic reflex occurs

• Typically measure ipsilateral and contralateral reflex thresholds at 500, 1000, and 2000 Hz

• May also measure acoustic reflex decay – how long does the reflex persist (stapedius continue contracting) for a continuous tone presented 10 dB above reflex threshold?

500, 1000, 2000Hz

• Normal acoustic reflex thresholds are 70 to 90 dB SL above the behavioral thresholds 

(85 to 100 dB SPL) - when you dont know the beginning behavioral thresholds 

• Absent or elevated reflexes indicate a problem somewhere on the acoustic reflex arc.

Possiblities: – Middle ear problem – Cochlear hearing loss – Auditory nerve problem – Facial nerve problem

sensorineural

• Acoustic reflex thresholds will occur at reduced sensation levels (< 70 dB SL)

• e.g., pure-tone threshold = 40 dB HL, acoustic reflex threshold = 80 dB HL (40 dB SL)

• Acoustic reflex threshold may be absent in presence of normal hearing

• e.g., pure-tone threshold = 10 dB HL, acoustic reflex threshold absent at 110 dB SPL (100 dB SL)

1. present reflex

2. reduced sensation level reflex

3. absent reflex

4. elevated reflex (fluid in ME)