Artificially enhancing better-ear glimpsing cues to improve understanding of speech in noise for listeners with hearing loss cues to improve understanding of speech in noise for listeners with hearing loss

1. Artificially enhancing better-ear glimpsing cues to improve understanding of speech in noise for
listeners with hearing loss
Baljeet Rana 1, 2, 3 and Jörg M. Buchholz 1, 2, 3
1. National Acoustic Laboratories, Sydney, NSW, Australia, 2. Department of Linguistics, Macquarie, University, Sydney, NSW, Australia,
3. The HEARing Cooperative Research Centre, Carlton, VIC, Australia
creating sound value www.hearingcrc.org
Background
Better-ear glimpsing (BEG)1 is an auditory process that takes
advantage of short-term interaural level differences (ILDs) to
improve the understanding of speech in spatial fluctuating
noise.
M
co-located
T
M M
spatially separated
M
Problem addressed
ILDs typically observed at
high frequencies (above about
1.5 kHz).
Aim 1
Most hearing-impaired (HI)
individuals have a greater degree
of hearing loss at high frequencies.
Would it help to provide BEG cues at
low frequencies through hearing aids?
To examine if normal-hearing (NH) and HI listeners can utilize
artificially extended low-frequency ILDs for BEG.
Methods
• 10 NH listeners (mean age=33 years).
• 10 HI listeners (mean age=67 years) with symmetrical,
sensorineural, mild-to-moderate hearing loss.
Frequency Low Mid High Broad
Hz 100-770 770-2.000 2.000-5.300 100-5.300
Spatial release from masking (SRM)
= SRT (co-located) –SRT (spatially separated)
Results
• Maskers: 35 dBSL w.r.t pure tone thresholds for NH listeners
10 dBSL w.r.t pure tone thresholds for HI listeners
Conclusion
• Both NH and HI listeners can utilize low-frequency ILDs for
improving speech understanding in noise 2.
• Overall performance as well as SRM was reduced in the HI
group, possibly due to differences in audibility.
Aim 2
To investigate if SRM in HI listeners can be restored across
frequency if audibility equivalent to NH listeners is provided.
• 10 NH listeners (mean age=23 years).
• 10 HI listeners (mean age=70 years) with symmetrical,
sensorineural, mild-to-moderate hearing loss.
• Measured individual speech detection thresholds (SDT) with
speech-shaped noise filtered into 9 different (2 CB wide)
frequency bands.
• Applied individual gain to equalize SDTs as a function of
frequency.
• Measured upper limits of comfort (ULC) in 4 frequency
regions for target and masker stimuli.
• Measured speech reception thresholds (SRTs) in quiet with
BKB-like sentences in four frequency regions .
• Target & Maskers: similar to previous experiment
• Maskers: 0, 10, 20 and 30 dB SL w.r.t. SRT in quiet.
-2
0
2
4
6
8
10
12
low mid high broadband
SRM(dB)
0 10 20 30
NHNHNH HIHIHINH HI
• Target: filtered BKB-like sentences.
• Maskers: filtered noise-vocoded speech (two talkers).
Speech reception thresholds (SRTs) in noise
HI listeners can achieve similar SRM as NH listeners if audibility
is compensated for.
Acknowledgements: International research excellence (iMQRES) scholarship and the Australian National Health and Medical Research Council (NHMRC) via grant APP1056332. Email: baljeet.rana@nal.gov.au
Methods
Speech reception thresholds (SRTs) in noise
Establishing the available dynamic range
Linear amplification
Results
Conclusions
References: 1) Brungart, D. S., and Iyer, N. (2012).“Better-ear glimpsing efficiency with
symmetrically-placed interfering talkers,” J. Acoust. Soc. Am. 132(4), 2545-2556. 2) Rana, B., and
Buchholz, J. M. (2016). “Better-ear glimpsing at low frequencies in normal-hearing and hearing-
impaired listeners,” J. Acoust. Soc. Am. 140 (2), 1192-1205.
T