title: Robustness against distortion of fundamental frequency cues in simulated electro-acoustic hearing.
abstract: Speech recognition by cochlear implant users can be improved by adding an audible low frequency acoustic signal to electrical hearing; the resulting improvement is deemed "electro-acoustic stimulation (EAS) benefit." However, a crucial low frequency cue, fundamental frequency (F0), can be distorted via the impaired auditory system. In order to understand how F0 distortions may affect EAS benefit, normal-hearing listeners were presented monaurally with vocoded speech (frequencies >250 Hz) and an acoustical signal (frequencies <250 Hz) with differing manipulations of the F0 signal, specifically: a pure tone with the correct mean F0 but with smaller variations around this mean, or a narrowband of white noise centered around F0, at varying bandwidths; a pure tone down-shifted in frequency by 50 Hz but keeping overall frequency modulations. Speech-recognition thresholds improved when tones with reduced frequency modulation were presented, and improved significantly for noise bands maintaining F0 information. A down-shifted tone, or only a tone to indicate voicing, showed no EAS benefit. These results confirm that the presence of the target's F0 is beneficial for EAS hearing in a noisy environment, and they indicate that the benefit is robust to F0 distortion, as long as the mean F0 and frequency modulations of F0 are preserved.
authors.affiliation: Hearing and Balance Centre, Institute of Sound and Vibration Research, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom.
authors.forename: Arthur
authors.initials: A
authors.lastname: Vermeulen
authors.affiliation: University of Southampton, Auditory Implant Service, Highfield, Southampton SO17 1BJ, United Kingdom.
authors.forename: Carl
authors.initials: C
authors.lastname: Verschuur
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D001309:Auditory Threshold; D003054:Cochlear Implants; D003463:Cues; D005260:Female; D006309:Hearing; D006801:Humans; D008297:Male; D009622:Noise; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult