The role of time and place cues in the detection of frequency modulation by hearing-impaired listeners.
Frequency modulation detection limens (FMDLs) were measured for five hearing-impaired (HI) subjects for carrier frequencies f(c) = 1000, 4000, and 6000 Hz, using modulation frequencies f(m) = 2 and 10 Hz and levels of 20 dB sensation level and 90 dB SPL. FMDLs were smaller for f(m) = 10 than for f(m) = 2 Hz for the two higher f(c), but not for f(c) = 1000 Hz. FMDLs were also determined with additional random amplitude modulation (AM), to disrupt excitation-pattern cues. The disruptive effect was larger for f(m) = 10 than for f(m) = 2 Hz. The smallest disruption occurred for f(m) = 2 Hz and f(c) = 1000 Hz. AM detection thresholds for normal-hearing and HI subjects were measured for the same f(c) and f(m) values. Performance was better for the HI subjects for both f(m). AM detection was much better for f(m)  = 10 than for f(m) = 2 Hz. Additional tests showed that most HI subjects could discriminate temporal fine structure (TFS) at 800 Hz. The results are consistent with the idea that, for f(m) = 2 Hz and f(c) = 1000 Hz, frequency modulation (FM) detection was partly based on the use of TFS information. For higher carrier frequencies and for all carrier frequencies with f(m) = 10 Hz, FM detection was probably based on place cues.
Department of Experimental Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, United Kingdom. stephan.ernst2@uni-oldenburg.de
Stephan M A
SM
Ernst
Brian C J
BC
Moore
D000161:Acoustic Stimulation; D000368:Aged; D000704:Analysis of Variance; D001309:Auditory Threshold / Q000502:physiology; D016022:Case-Control Studies; D003463:Cues; D034381:Hearing Loss / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019986:Persons with Hearing Disabilities; D010897:Pitch Discrimination / Q000502:physiology*; D013017:Sound Localization / Q000502:physiology; D013997:Time Factors