TY - JOUR
T1 - Single Band Amplitude Envelope Cues as an Aid to Speechreading
AU - Grant, Ken W.
AU - Braida, Louis D.
AU - Renn, Rebecca J.
N1 - Funding Information:
The authors wish to thank Quentin Summerfield, Arthur Boothroyd, William Rabinowitz, and an anonymous reviewer for their helpful comments on earlier drafts of this manuscript. This research was supported by NIH grants DC 00010 and DC 001 17 to Massachusetts Institute of Technology, Cambridge, Massachusetts.
PY - 1991/8/1
Y1 - 1991/8/1
N2 - Amplitude envelopes derived from speech have been shown to facilitate speechreading to varying degrees, depending on how the envelope signals were extracted and presented and on the amount of training given to the subjects. In this study, three parameters related to envelope extraction and presentation were examined using both easy and difficult sentence materials: (1) the bandwidth and centre frequency of the filtered speech signal used to obtain the envelope; (2) the bandwidth of the envelope signal determined by the lowpass filter cutoff frequency used to “smooth” the envelope fluctuations; and (3) the carrier signal used to convey the envelope cues. Results for normal hearing subjects following a brief visual and auditory-visual familiarization/training period showed that (1) the envelope derived from wideband speech does not provide the greatest benefit to speechreading when compared to envelopes derived from selected octave bands of speech; (2) as the bandwidth centred around the carrier frequency increased from 12.5 to 1600 Hz, auditory-visual (AV) performance obtained with difficult sentence materials improved, especially for envelopes derived from high-frequency speech energy; (3) envelope bandwidths below 25 Hz resulted in AV scores that were sometimes equal to or worse than speechreading alone; (4) for each filtering condition tested, there was at least one bandwidth and carrier condition that produced AV scores that were significantly greater than speechreading alone; (5) low-frequency carriers were better than high-frequency or wideband carriers for envelopes derived from an octave band of speech centred at 500 Hz; and (6) low-frequency carriers were worse than high-frequency or wideband carriers for envelopes derived from an octave band centred at 3150 Hz. These results suggest that amplitude envelope cues can provide a substantial benefit to speechreading for both easy and difficult sentence materials, but that frequency transposition of these signals to regions remote from their “natural” spectral locations may result in reduced performance.
AB - Amplitude envelopes derived from speech have been shown to facilitate speechreading to varying degrees, depending on how the envelope signals were extracted and presented and on the amount of training given to the subjects. In this study, three parameters related to envelope extraction and presentation were examined using both easy and difficult sentence materials: (1) the bandwidth and centre frequency of the filtered speech signal used to obtain the envelope; (2) the bandwidth of the envelope signal determined by the lowpass filter cutoff frequency used to “smooth” the envelope fluctuations; and (3) the carrier signal used to convey the envelope cues. Results for normal hearing subjects following a brief visual and auditory-visual familiarization/training period showed that (1) the envelope derived from wideband speech does not provide the greatest benefit to speechreading when compared to envelopes derived from selected octave bands of speech; (2) as the bandwidth centred around the carrier frequency increased from 12.5 to 1600 Hz, auditory-visual (AV) performance obtained with difficult sentence materials improved, especially for envelopes derived from high-frequency speech energy; (3) envelope bandwidths below 25 Hz resulted in AV scores that were sometimes equal to or worse than speechreading alone; (4) for each filtering condition tested, there was at least one bandwidth and carrier condition that produced AV scores that were significantly greater than speechreading alone; (5) low-frequency carriers were better than high-frequency or wideband carriers for envelopes derived from an octave band of speech centred at 500 Hz; and (6) low-frequency carriers were worse than high-frequency or wideband carriers for envelopes derived from an octave band centred at 3150 Hz. These results suggest that amplitude envelope cues can provide a substantial benefit to speechreading for both easy and difficult sentence materials, but that frequency transposition of these signals to regions remote from their “natural” spectral locations may result in reduced performance.
UR - http://www.scopus.com/inward/record.url?scp=0026201759&partnerID=8YFLogxK
U2 - 10.1080/14640749108400990
DO - 10.1080/14640749108400990
M3 - Article
C2 - 1775660
AN - SCOPUS:0026201759
SN - 0272-4987
VL - 43
SP - 621
EP - 645
JO - The Quarterly Journal of Experimental Psychology Section A
JF - The Quarterly Journal of Experimental Psychology Section A
IS - 3
ER -