Measurement of the Electrically Evoked Stapedial Reflex Response with Wideband Acoustic Reflectance Measurement

Background: The electrically evoked stapedial reflex threshold (ESRT) has been shown to be a good predictor of upper stimulation level for cochlear implant recipients. Previous research has shown that the ESRT may be recorded at lower stimulation levels and with a higher incidence of success with the use of higher frequency probe tones (e.g., 678 and 1000 Hz) relative to the use of the conventional 226-Hz probe tone. Research has also shown that the acoustic reflex may be recorded at lower stimulus levels with the use of wideband reflectance when compared to the acoustic reflex threshold recorded with a conventional acoustic immittance measurement.

Purpose: The objective of this study was to compare the ESRT recorded with acoustic immittance and wideband reflectance measurements.

Research design: A repeated measures design was used to evaluate potential differences in ESRTs with stimulation at an apical, middle, and basal electrode contact with the use of two different techniques, acoustic immittance measurement and wideband reflectance.

Study sample: Twelve users of Cochlear Nucleus cochlear implants were included in the study.

Data collection and analysis: Participants' ESRTs were evaluated in response to simulation at three different electrode contact sites (i.e., an apical, middle, and basal electrode contact) with the use of two different middle ear measurement techniques, acoustic immittance with the use of a 226-Hz probe tone and wideband reflectance with the use of a chirp stimulus.

Results: The mean ESRT recorded with wideband reflectance measurement was significantly lower when compared to the ESRT recorded with acoustic immittance. For one participant, the ESRT was not recorded with acoustic immittance before reaching the participant's loudness discomfort threshold, but it was successfully recorded with the use of wideband reflectance.

Conclusions: The ESRT may potentially be recorded at lower presentation levels with the use of wideband reflectance measures relative to the use of acoustic immittance with a 226-Hz probe tone. This may allow for the ESRT to be obtained at levels that are more comfortable for the cochlear implant recipient, which may also allow for a higher incidence in the successful recording of the ESRT.