Jens Blauert, Bochum

Binaural Hearing and Human Sound Localization

Physics Psychophysics

“sounds” “sensations”

Psychophysics“sensations”

Physics“sounds”

ακούειν (akúın)to hear

Acoustics

acoustic event auditory event

Head-Related Coordinate System

Some Key Words

Effect of Head Movement

Binaural Hearing and Human Sound Localization

- Introductory remarks - Directional hearing in the median sagittal plane - Directional hearing with sounds from lateral directions - Distance perception and inside-the-head locatedness - Summing localization - Auditory precedence and the echo threshold - The effect of interaural decorrelation - Binaural signal detection - Suppression of reverberance and coloration - Summary

Directional hearing in the median sagittal plane

Directional Hearing in the Median Sagittal Plane

Directional Hearing in the Median Plane

directionalbands

boosted bands

1/3 octnoise

Directional Hearing with Sounds from Lateral Directions

Lateralization

ear axis

Generation of ITDs and ILDs

attenuatorsdelay lines

Lateralization Blur for ILDs

Lateralization Due to ILDs

Lateralization Blur for ITDs

ITD-Lateralization Cues

right ear

left ear

Lateralization due to ITDs (broad-band signals)

Distance Perception Inside-the-Head Locatedness

Summing Localization Auditory Precedence

Echoes

Standard Stereo-Listening Arrangement

Summing Localization for Broad-Band Sounds

Ear Signals for Impulsive Sounds in Stereo

Summing Localization with Sideways Loudspeakers

after Plenge & Theile

Auditory Effects with Two Coherent Sound Sources

Summing localization Precedence Effect Echo Threshold

broad-bandsounds

primary auditory event

echo

Precedence Effect, Haas Effect and Backward Inhibition

signal: running speech of 50 syllables/s

delay of the reflection

The Effect of Interaural Decorrelation

Some Further Key Words

Controlling the Degree of Coherence

3 independentnoise generators

Spatial Extent of the Auditory Event as a Function of Interaural Correlation

after Dubrovski & Cherniak, 1966

The Perceptive Phenomena of „Auditory Spaciousness“

Pioneer researches e.g., Kuhl, West, Marshall, Barron, Schroeder, Morimoto

Binaural Signal Detection Suppression of Reverberance

and Coloration

The Binaural Intellegibility–Level Difference, BILDCherry’s Experiment

Binaural Suppression of ReverberanceDanilenko’s Experiment

degree of AM, m

reverberant chamber

reverb

anechoicthre

shol

d of

per

cept

ibili

ty

higher localization accuracy, lower blurbetter source segregation (transparency)

suppression of undesired signals (cocktail-party effect)suppression of coloration and reverberance (better articulation)

>> clearer auditory perspective<<

better sense of envelopmenthigher auditory source width (auditory spaciousness)

>> better spatial impression<<

Advantages of Binaural Hearing

Higher Quality of the „Acoustics“!

jens.blauert@rub.de www.ruhr-uni-bochum.de/ika

Thank You for Your Attention

More details regarding the topic of this lecture can be found in

Jens Blauert (1997)

Spatial Hearing:The Psychophysics of Human Sound Localization

published by

The MIT Press, Harvard MA, ISBN 0-262-02413-6

TASK A

Young men and women (about 30 years old) have applied to be admitted to a school for airline pilots.

For being accepted, they must have very good spatial-hearing capabilities.

This is necessary, among other reasons, because they have to respond correctly to signals from auditory displays in the cockpit.

Outline a battery of perceptual tests which could be used to evaluate these capabilities.

(a) What would you measure?(b) Which methods would you apply?(c) What equipment would you need?

TASK B

The binaural-hearing capabilities of elderly people (over 65 years) are to be evaluated by means of routine screening tests.

The goal is to assess their abilities to localize sounds in space and to communicate under acoustically adverse conditions.

The information is needed , among other reasons, to decide if hearings aids should be applied to them – and, if yes, which kind of these?

Outline a battery of perceptual tests that could be used to evaluate these capabilities.

(a) What would you measure?(b) Which methods would you apply?(c) What equipment would you need?