title: Effects of contextual cues on speech recognition in simulated electric-acoustic stimulation.
abstract: Low-frequency acoustic cues have shown to improve speech perception in cochlear-implant listeners. However, the mechanisms underlying this benefit are still not well understood. This study investigated the extent to which low-frequency cues can facilitate listeners' use of linguistic knowledge in simulated electric-acoustic stimulation (EAS). Experiment 1 examined differences in the magnitude of EAS benefit at the phoneme, word, and sentence levels. Speech materials were processed via noise-channel vocoding and lowpass (LP) filtering. The amount of spectral degradation in the vocoder speech was varied by applying different numbers of vocoder channels. Normal-hearing listeners were tested on vocoder-alone, LP-alone, and vocoder + LP conditions. Experiment 2 further examined factors that underlie the context effect on EAS benefit at the sentence level by limiting the low-frequency cues to temporal envelope and periodicity (AM + FM). Results showed that EAS benefit was greater for higher-context than for lower-context speech materials even when the LP ear received only low-frequency AM + FM cues. Possible explanations for the greater EAS benefit observed with higher-context materials may lie in the interplay between perceptual and expectation-driven processes for EAS speech recognition, and/or the band-importance functions for different types of speech materials.
authors.affiliation: Department of Communication Sciences and Disorders, Northeastern University, 226 Forsyth Building, 360 Huntington Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Ying-Yee
authors.initials: YY
authors.lastname: Kong
authors.affiliation: Department of Communication Sciences and Disorders, University of South Florida, PCD 1017, 4202 East Fowler Avenue, Tampa, Florida 33620, USA.
authors.forename: Gail
authors.initials: G
authors.lastname: Donaldson
authors.affiliation: Department of Bioengineering, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Ala
authors.initials: A
authors.lastname: Somarowthu
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000162:Acoustics; D000293:Adolescent; D000328:Adult; D001302:Audiometry, Speech; D003198:Computer Simulation; D003463:Cues; D006801:Humans; D010507:Periodicity; D010700:Phonetics; D021641:Recognition, Psychology; D013018:Sound Spectrography; D013061:Speech Acoustics; D013067:Speech Perception; D013997:Time Factors; D014833:Voice Quality; D055815:Young Adult