Objective assessment of multichannel cochlear implants: comparison between different strategies for vowel recognition.
Source: Acustica 84(5):918-28.
Abstract: The paper proposes a method to enable the assessment and improve the speech recognition performance with cochlear implants (CIs). The CI bases this method on the processing of large speech databases. It involves the TRANSCLAS method, which transfers of the output signals from the implants on computer for classification into phonetic categories. It was indicated by the automatic assessments obtained with a Digisonic DX10 that "Mel" tuning strategy gives a more correct classification of vowels. Unlike the "Linear" strategy in which channel frequencies are equally spaced in Hz, the "Mel" strategy has a Digisonic channels spaced at equal intervals on a psychoacoustic scale. The higher density of channels in the range of formant frequency improves the performance of this strategy. This study explores "Mel Modified High Shaping Strategy" (MMHS), which attempts to improve the implant performance by increasing the channel density further in the formant frequency range, and by using energy gain of 6 dB per octave. These strategy modifications have a slightly lower performance when all the fifteen channels are active, as shown by the automatic assessments. The MMHS strategy makes the vowel recognition less resistant to signal distortions. (CIRRIE Abstract)
Institution: Lab. de Stat. Med., Univ. Libre de Bruxelles, Belgium