Assessment of adjustment to electrical threshold (T) level and electrical stimulation rate on IDL and AM detection at soft presentation level in adult CI users
* Presenting author
Cochlear Implant (CI) users often show poorer speech perception at low intensity levels.Very little is understood about the influence of sound processor fitting parameters on the discrimination of low intensity acoustic cues. A pilot study was conducted to evaluate the influence of electrical stimulation rate and the setting of electrical threshold (T) Level on intensity difference limens (IDLs) and amplitude modulation (AM) discrimination.Participants were thirteen adult experienced Advanced Bionics CI users. The frequency of the acoustic sinusoidal stimuli was set to 1076Hz with the intention of stimulating electrode seven. Nine experimental maps were created with T levels set at: the perceptual threshold of audibility; perceptually equivalent to ‘very soft’ and 10% of the perceptual equivalent to ‘most comfortable loudness’. Rates of electrical stimulation used were 900, 1800 and 2700 pulses-per-second. Adaptive 2I-2AFC IDL and AM discrimination tasks were presented via headphones at soft presentation levels (48 and 54dBSPL for IDL and AM tasks respectively). The influence of T Level and stimulation rate adjustments on IDL and AM detection have been explored with the intention of understanding the impact of altering individual parameter settings to optimise detection of acoustic cues at low presentation levels.