# Spatial hearing in speech mixtures

> **NIH NIH R01** · BOSTON UNIVERSITY (CHARLES RIVER CAMPUS) · 2020 · $315,563

## Abstract

Abstract
The goal of this work is to clarify the role of spatial factors in the difficulty experienced by listeners with hearing
impairment (HI) in understanding the speech of one particular talker in a mixture of talkers. Because HI listeners
perform poorly when competing talkers are spatially separated, it is often assumed that an inability to exploit
spatial cues is at the root of the problem. However, direct evidence for spatial deficits in HI listeners is lacking,
as are clear links between spatial hearing and speech intelligibility. The experiments proposed here will carefully
unpack and characterize the mechanisms affecting listeners with hearing loss in spatialized speech mixtures.
The experiments proposed under Aim 1 will focus on the impact of reduced audibility, and determine the extent
to which this basic deficit limits access to spatial information in addition to speech information. A stimulus
processing approach that isolates clean “glimpses” of the target sound in speech mixtures will enable intelligibility
to be assessed in the absence of any explicit spatial task. Controlled manipulation of the spatial cues available
in the stimuli will reveal the extent to which acoustic head-shadow contributes to the glimpses. Experiments
under this aim will also explore the conditions under which access to high frequencies in speech is critical, and
relate this knowledge to the benefits obtained from high-frequency amplification hearing aids. The experiments
proposed under Aim 2 are designed to clarify the role of binaural temporal fine structure (TFS) in speech
mixtures. The working hypothesis is that, although the amplitude envelopes of speech convey the primary
information needed for high intelligibility, TFS carries auxiliary cues for sound source location that enable
segregation of competing sounds. This hypothesis will be tested by comparing the effect of disrupting TFS on
speech intelligibility for mixtures in which segregation is difficult versus relatively automatic. Parallel experiments
will measure discrimination of the spatial location of speech sounds under the same conditions, in order to directly
explore the link between spatial hearing and speech source segregation. Experiments in HI listeners will reveal
whether these listeners exhibit an impairment specifically involving binaural TFS, an issue that remains
unresolved in the literature. A critical aspect of this work will be to carefully consider the relationship between
“acoustic” TFS (extracted using signal processing techniques) and "neural" TFS (as coded in the auditory-nerve)
in the context of speech signals. The experiments proposed under Aim 3 will examine a relatively unexplored
but potentially crucial aspect of listening in speech mixtures: the rapid improvement in intelligibility over time that
occurs when the listening environment is stable (e.g., when the talker of interest stays fixed at one location). A
new speech task will be created that is optimized to observe...

## Key facts

- **NIH application ID:** 9823869
- **Project number:** 5R01DC015760-04
- **Recipient organization:** BOSTON UNIVERSITY (CHARLES RIVER CAMPUS)
- **Principal Investigator:** Virginia Ann Best
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $315,563
- **Award type:** 5
- **Project period:** 2016-12-09 → 2021-11-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9823869

## Citation

> US National Institutes of Health, RePORTER application 9823869, Spatial hearing in speech mixtures (5R01DC015760-04). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9823869. Licensed CC0.

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