Shifting fundamental frequency in simulated electric-acoustic listening

Previous experiments have shown significant improvement in speech intelligibility under both simulated [ Brown, C. A. , and Bacon, S. P. ( 2009a ). J. Acoust. Soc. Am. 125 , 1658-1665 ; Brown, C. A. , and Bacon, S. P. ( 2010 ). Hear. Res. 266 , 52-59 ] and real [ Brown, C. A. , and Bacon, S. P. ( 2009b ). Ear Hear. 30 , 489-493 ] electric-acoustic stimulation when the target speech in the low-frequency region was replaced with a tone modulated in frequency to track the changes in the target talker's fundamental frequency (F0), and in amplitude with the amplitude envelope of the target speech. The present study examined the effects in simulation of applying these cues to a tone lower in frequency than the mean F0 of the target talker. Results showed that shifting the frequency of the tonal carrier downward by as much as 75 Hz had no negative impact on the benefit to intelligibility due to the tone, and that even a shift of 100 Hz resulted in a significant benefit over simulated electric-only stimulation when the sensation level of the tone was comparable to that of the tones shifted by lesser amounts.