Intelligibility of frequency-lowered speech produced by a channel vocoder.

نویسندگان

  • M P Posen
  • C M Reed
  • L D Braida
چکیده

Frequency lowering is a form of signal processing designed to match speech to the residual auditory capacity of a listener with a high frequency hearing loss. A vocoder-based frequency-lowering system similar to one studied by Lippmann was evaluated in the present study. In this system, speech levels in high frequency bands modulated one-third-octave bands of noise at low frequencies, which were then added to unprocessed speech. Results obtained with this system indicated, in agreement with Lippmann, that processing improved the recognition of stop, fricative, and affricate consonants when the listening bandwidth was restricted to 800 Hz. However, results also showed that processing degraded the perception of nasals and semivowels, consonants not included in Lippmann's study. Based on these results, the frequency-lowering system was modified so as to suppress the processing whenever low frequency components dominated the input signal. High and low frequency energies of an input signal were measured continuously in the modified system, and the decision to process or to leave the signal unaltered was based on their relative levels. Results indicated that the modified system maintained the processing advantage for stops, fricatives, and affricates without degrading the perception of nasals and semi-vowels. The results of the present study also indicated that training is an important consideration when evaluating frequency-lowering systems.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Evaluation of companding-based spectral enhancement using simulated cochlear-implant processing.

This study tested a time-domain spectral enhancement algorithm that was recently proposed by Turicchia and Sarpeshkar [IEEE Trans. Speech Audio Proc. 13, 243-253 (2005)]. The algorithm uses a filter bank, with each filter channel comprising broadly tuned amplitude compression, followed by more narrowly tuned expansion (companding). Normal-hearing listeners were tested in their ability to recogn...

متن کامل

Simulations of High-Frequency Vocoder on Mandarin Speech Recognition for Acoustic Hearing Preserved Cochlear Implant

Vocoder simulations are generally adopted to simulate the electrical hearing induced by the cochlear implant (CI). Our research group is developing a new four-electrode CI microsystem which induces high-frequency electrical hearing while preserving low-frequency acoustic hearing. To simulate the functionality of this CI, a previously developed hearing-impaired (HI) hearing model is combined wit...

متن کامل

The Effects of Phase Information on the Intelligibility of Channel Vocoded Speech

The intelligibility of vocoded speech with various phase spectra was compared to the intelligibility of the original input natural speech. It was found that vocoded speech with true natural phase was the closest to natural speech in intelligibility.

متن کامل

Effects of envelope filter cutoff frequency on the intelligibility of Mandarin noise-vocoded speech in babble noise: implications for cochlear implants

In cochlear implants, limited spectral and temporal information is provided. Previous studies argued for different effects of temporal information on speech identification in adverse environments. Particularly, it is unclear how speech intelligibility is influenced by the low-pass cutoff frequency of temporal envelope extractors in noise. The current study explored this issue with Mandarin nois...

متن کامل

Speech enhancement for bandlimited speech

Throughout the history of telecommunication, speech has rarely been transmitted with its full analog bandwidth (0 to 8 kHz or more) due to limitations in channel bandwidth. This impaired legacy continues with tactical voice communication. The passband of a voice terminal is typically 0 to 4 kHz. Hence, high-frequency speech components (4 to 8 kHz) are removed prior to transmission. As a result,...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Journal of rehabilitation research and development

دوره 30 1  شماره 

صفحات  -

تاریخ انتشار 1993