The performance of different synthesis signals in acoustic models of cochlear implants

• Published in: The Journal of the Acoustical Society of America Vol. 129; no. 2; p. 920
• Main Authors: Strydom, Trudie, Hanekom, Johan J
• Format: Journal Article
• Language: English
• Published: United States 01.02.2011
• Subjects: Acoustic Stimulation; Adolescent; Adult; Analysis of Variance; Audiometry, Speech; Auditory Threshold; Cochlear Implants; Humans; Prosthesis Design; Signal Processing, Computer-Assisted; Sound Spectrography; Speech Acoustics; Speech Intelligibility; Speech Perception; Time Factors; Young Adult
• ISSN: 1520-8524
• DOI: 10.1121/1.3518760

Synthesis (carrier) signals in acoustic models embody assumptions about perception of auditory electric stimulation. This study compared speech intelligibility of consonants and vowels processed through a set of nine acoustic models that used Spectral Peak (SPEAK) and Advanced Combination Encoder (ACE)-like speech processing, using synthesis signals which were representative of signals used previously in acoustic models as well as two new ones. Performance of the synthesis signals was determined in terms of correspondence with cochlear implant (CI) listener results for 12 attributes of phoneme perception (consonant and vowel recognition; F1, F2, and duration information transmission for vowels; voicing, manner, place of articulation, affrication, burst, nasality, and amplitude envelope information transmission for consonants) using four measures of performance. Modulated synthesis signals produced the best correspondence with CI consonant intelligibility, while sinusoids, narrow noise bands, and varying noise bands produced the best correspondence with CI vowel intelligibility. The signals that performed best overall (in terms of correspondence with both vowel and consonant attributes) were modulated and unmodulated noise bands of varying bandwidth that corresponded to a linearly varying excitation width of 0.4 mm at the apical to 8 mm at the basal channels.