Speech-Envelope Cues as an Acoustic Aid to Lipreading for Profoundly Deaf Children
Norman P. Erber · The Journal of the Acoustical Society of America · 1972
A speaker recorded lists of words on video tape. These lists were presented to normally hearing children and adults and to profoundly deaf children (average hearing threshold level greater than 95 dB ISO) for recognition through visual or combined acoustic-visual (A-V) modalities. For the normals, the acoustic stimulus was a 500-Hz octave-band noise amplitude-modulated by the envelope of the speech signal. For the profoundly deaf observers, the acoustic signal was either modulated noise or linearly amplified speech. Regardless of the type of acoustic signal they received, the mean A-V scores of the deaf children were 7% to 11% higher than their mean visual scores. The normals also demonstrated small mean improvements (6% to 8%) over visual reception when allowed both to watch the speaker's face and to listen to modulated noise. These results suggest that profoundly deaf children perceive mainly time-intensity (envelope) information when they are provided with an amplified speech signal.