Estimating azimuth and elevation from interaural differences

PurposeFor listeners with single-sided deafness, a cochlear implant (CI) can improve speech understanding by giving the listener access to the ear with the better target-to-masker ratio (TMR; head shadow) or by providing interaural difference cues to facilitate the perceptual separation of concurrent talkers (squelch). CI simulations presented to listeners with normal hearing examined how these benefits could be affected by interaural differences in loudness growth in a speech-on-speech masking task.MethodExperiment 1 examined a target–masker spatial configuration where the vocoded ear had a poorer TMR than the nonvocoded ear. Experiment 2 examined the reverse configuration. Generic head-related transfer functions simulated free-field listening. Compression or expansion was applied independently to each vocoder channel (power-law exponents: 0.25, 0.5, 1, 1.5, or 2).ResultsCompression reduced the benefit provided by the vocoder ear in both experiments. There was some evidence that expansion increased squelch in Experiment 1 but reduced the benefit in Experiment 2 where the vocoder ear provided a combination of head-shadow and squelch benefits.ConclusionsThe effects of compression and expansion are interpreted in terms of envelope distortion and changes in the vocoded-ear TMR (for head shadow) or changes in perceived target–masker spatial separation (for squelch). The compression parameter is a candidate for clinical optimization to improve single-sided deafness CI outcomes.

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Temporal weighting of binaural cues revealed by detection of dynamic interaural differences in high-rate Gabor click trains

The Journal of the Acoustical Society of America ◽

10.1121/1.3377088 ◽

2010 ◽

Vol 127 (5) ◽

pp. 3092-3103 ◽

Cited By ~ 28

Author(s):

G. Christopher Stecker ◽

Andrew D. Brown

Keyword(s):

High Rate ◽

Binaural Cues ◽

Interaural Differences

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Normative study of tympanic infrared thermometry: a non-invasive index of asymmetric cerebral activity

Arquivos de Neuro-Psiquiatria ◽

10.1590/s0004-282x2008000100012 ◽

2008 ◽

Vol 66 (1) ◽

pp. 50-52 ◽

Cited By ~ 1

Author(s):

Danielle Cicarini de Landa ◽

Joaquim P. Brasil-Neto ◽

Raphael Boechat-Barros ◽

Carlos Uribe

Keyword(s):

Normal Subjects ◽

Tympanic Temperature ◽

Normative Values ◽

Normative Study ◽

Infrared Thermometry ◽

Cerebral Activity ◽

Confidence Levels ◽

Non Invasive ◽

Neurological Patients ◽

Interaural Differences

Human and primate studies have demonstrated that performance of tasks that induce asymmetrical physiological activation of the cerebral hemispheres leads to a reduction of tympanic temperature (TT) ipsilateral to the most active hemisphere. It is possible that diseases that interfere in an asymmetrical fashion with the degree of cerebral activity cause similar TT changes. There are not, however, normative studies of the acceptable interaural difference in TT in normal subjects at rest. This study was done to establish normative values for interaural TT values measured by means of infrared tympanic thermometry in resting normal subjects not engaged in any specific task. TT values were measured in 47 normal volunteers (20 men and 27 women, aged 39.38±12.57 years old) at rest; mean interaural differences of TT were calculated. Mean right ear TT was 36.85±0.50ºC and mean left ear TT was 36.74±0.57ºC; these values are in agreement with those already reported in the literature. Mean interaural TT difference was 0.25ºC (SD 0.21ºC). These findings indicate that maximal normal values for interaural TT differences, with confidence levels of 99% and 95%, are, respectively, 0.88 and 0.67ºC. The value of interaural differences of TT as a marker of asymmetrical hemispheric activity in neurological patients will have to be established by additional studies.

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