title: Perception of stochastic envelopes by normal-hearing and cochlear-implant listeners.
abstract: We assessed auditory sensitivity to three classes of temporal-envelope statistics (modulation depth, modulation rate, and comodulation) that are important for the perception of 'sound textures'. The textures were generated by a probabilistic model that prescribes the temporal statistics of a selected number of modulation envelopes, superimposed onto noise carriers. Discrimination thresholds were measured for normal-hearing (NH) listeners and users of a MED-EL pulsar cochlear implant (CI), for separate manipulations of the average rate and modulation depth of the envelope in each frequency band of the stimulus, and of the co-modulation between bands. Normal-hearing (NH) listeners' discrimination of envelope rate was similar for baseline modulation rates of 5 and 34 Hz, and much poorer than previously reported for sinusoidally amplitude-modulated sounds. In contrast, discrimination of model parameters that controlled modulation depth was poorer at the lower baseline rate, consistent with the idea that, at the lower rate, subjects get fewer 'looks' at the relevant information when comparing stimuli differing in modulation depth. NH listeners could discriminate differences in co-modulation across bands; a multidimensional scaling study revealed that this was likely due to genuine across-frequency processing, rather than within-channel cues. CI users' discrimination performance was worse overall than for NH listeners, but showed a similar dependence on stimulus parameters.
authors.affiliation: MRC Cognition & Brain Sciences Unit, 15 Chaucer Rd., Cambridge, England, United Kingdom; Addenbrookes NHS Trust, Hills Rd., Cambridge, England, United Kingdom; Anglia Ruskin University, East Rd, Cambridge, England, United Kingdom. Electronic address: Philip.Gomersall@mrc-cbu.cam.ac.uk.
authors.forename: Philip A
authors.initials: PA
authors.lastname: Gomersall
authors.affiliation: Dept. Engineering, University of Cambridge, Trumpington Street, Cambridge, England, United Kingdom. Electronic address: ret26@cam.ac.uk.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Turner
authors.affiliation: Addenbrookes NHS Trust, Hills Rd., Cambridge, England, United Kingdom; Anglia Ruskin University, East Rd, Cambridge, England, United Kingdom. Electronic address: dmb29@cam.ac.uk.
authors.forename: David M
authors.initials: DM
authors.lastname: Baguley
authors.affiliation: MRC Cognition & Brain Sciences Unit, 15 Chaucer Rd., Cambridge, England, United Kingdom. Electronic address: John.Deeks@mrc-cbu.cam.ac.uk.
authors.forename: John M
authors.initials: JM
authors.lastname: Deeks
authors.affiliation: MRC Cognition & Brain Sciences Unit, 15 Chaucer Rd., Cambridge, England, United Kingdom. Electronic address: Hedwig.Gockel@mrc-cbu.cam.ac.uk.
authors.forename: Hedwig E
authors.initials: HE
authors.lastname: Gockel
authors.affiliation: MRC Cognition & Brain Sciences Unit, 15 Chaucer Rd., Cambridge, England, United Kingdom. Electronic address: Bob.Carlyon@mrc-cbu.cam.ac.uk.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Carlyon
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000162:Acoustics; D001299:Audiometry; D001307:Auditory Perception; D001309:Auditory Threshold; D016022:Case-Control Studies; D019929:Cochlear Implantation / Q000295:instrumentation*; D003054:Cochlear Implants; D003463:Cues; D004192:Discrimination, Psychological; D004558:Electric Stimulation; D006801:Humans; D046709:Pattern Recognition, Physiological; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D011571:Psychoacoustics; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013269:Stochastic Processes
keywords: Cochlear implants; Envelope discrimination; Sound textures