TY - JOUR
T1 - Measuring access to high-modulation-rate envelope speech cues in clinically fitted auditory prostheses
AU - Stone, Michael
AU - Prendergast, Garreth
AU - Canavan, Shanelle
PY - 2020
Y1 - 2020
N2 - The signal processing used to increase intelligibility within the hearing-impaired listener introduces distortions in the modulation patterns of a signal. Trade-offs have to be made between improved audibility and the loss of fidelity. Acoustic hearing impairment can cause reduced access to temporal fine structure (TFS), while cochlear implant processing, used to treat profound hearing impairment, has reduced ability to convey TFS, hence forcing greater reliance on modulation cues.
Target speech mixed with a competing talker was split into 12-22 frequency channels. From each channel, separate low-rate (EmodL, < 16 Hz), and high-rate (EmodH, < 300 Hz) versions of the envelope modulation were extracted, which resulted in low or high intelligibility, respectively. The EModL modulations were preserved in channel valleys, and cross-faded to EModH in channel peaks. The cross-faded signal modulated a tone carrier in each channel. The modulated carriers were summed across channels and presented to hearing-aid and cochlear-implant users. Their ability to access high-rate modulation cues, and the dynamic range of this access, was assessed. Clinically fitted hearing aids resulted in 10% lower intelligibility than simulated high-quality aids. Encouragingly, cochlear implantees were able to extract high-rate information over a dynamic range similar to that for the hearing-aid users.
AB - The signal processing used to increase intelligibility within the hearing-impaired listener introduces distortions in the modulation patterns of a signal. Trade-offs have to be made between improved audibility and the loss of fidelity. Acoustic hearing impairment can cause reduced access to temporal fine structure (TFS), while cochlear implant processing, used to treat profound hearing impairment, has reduced ability to convey TFS, hence forcing greater reliance on modulation cues.
Target speech mixed with a competing talker was split into 12-22 frequency channels. From each channel, separate low-rate (EmodL, < 16 Hz), and high-rate (EmodH, < 300 Hz) versions of the envelope modulation were extracted, which resulted in low or high intelligibility, respectively. The EModL modulations were preserved in channel valleys, and cross-faded to EModH in channel peaks. The cross-faded signal modulated a tone carrier in each channel. The modulated carriers were summed across channels and presented to hearing-aid and cochlear-implant users. Their ability to access high-rate modulation cues, and the dynamic range of this access, was assessed. Clinically fitted hearing aids resulted in 10% lower intelligibility than simulated high-quality aids. Encouragingly, cochlear implantees were able to extract high-rate information over a dynamic range similar to that for the hearing-aid users.
KW - dip-listening
KW - glimpsing
KW - dynamic range compression
KW - modulations
KW - hearing aids
KW - cochlear implants
KW - auditory perception
KW - speech intelligibility
U2 - 10.1121/10.0000673
DO - 10.1121/10.0000673
M3 - Article
SN - 0001-4966
JO - Journal of the Acoustical Society of America
JF - Journal of the Acoustical Society of America
ER -