Audiology by Alexandros G. Sfakianakis

Τετάρτη 24 Φεβρουαρίου 2016

Transaural experiments and a revised duplex theory for the localization of low-frequency tones

The roles of interaural time difference(ITD) and interaural level difference (ILD) were studied in free-field source localization experiments for sine tones of low frequency (250–750 Hz). Experiments combined real-source trials with virtual trials created through transaural synthesis based on real-time ear canal measurements. Experiments showed the following: (1) The naturally occurring ILD is physically large enough to exert an influence on sound localization well below 1000 Hz. (2) An ILD having the same sign as the ITD modestly enhances the perceived azimuth of tones for all values of the ITD, and it eliminates left-right confusions that otherwise occur when the interaural phase difference (IPD) passes 180°. (3) Increasing the ILD to large, implausible values can decrease the perceived laterality while also increasing front-back confusions. (4) Tone localization is more directly related to the ITD than to the IPD. (5) An ILD having a sign opposite to the ITD promotes a slipped-cycle ITD, sometimes with dramatic effects on localization. Because the role of the ITD itself is altered by the ILD, the duplex processing of ITD and ILD reflects more than mere trading; the effect of the ITD can be reversed in sign.

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Comment on 'International collegium of rehabilitative audiology (ICRA) recommendations for the construction of multilingual speech tests', by Akeroyd et al.

Comment on 'International collegium of rehabilitative audiology (ICRA) recommendations for the construction of multilingual speech tests', by Akeroyd et al.

Int J Audiol. 2016 Apr;55(4):268-271

Authors: Smits C

PMID: 26903088 [PubMed - as supplied by publisher]

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Efficacy of earphones for 12- to 24-month-old children during visual reinforcement audiometry.

Efficacy of earphones for 12- to 24-month-old children during visual reinforcement audiometry.

Int J Audiol. 2016 Apr;55(4):248-253

Authors: Weiss AD, Karzon RK, Ead B, Lieu JE

Abstract
OBJECTIVE: Efficacy of insert and supra-aural earphones during visual reinforcement audiometry (VRA) was investigated for 12- to 24-month-old children.
DESIGN: VRA testing began in the soundfield and transitioned to either insert or supra-aural earphones. Audiologists recorded threshold estimates, participant behaviors, and an overall subjective rating of earphone acceptance.
STUDY SAMPLE: One hundred and eighty-six 12- to 24-month-old children referred to the Department of Audiology at St. Louis Children's Hospital for a variety of reasons.
RESULTS: Subjective ratings indicated high acceptance of insert earphones (84%) and supra-aural earphones (80%) despite negative behaviors. There was no significant difference in the number of threshold estimates based on earphone type for 12- to 17-month-old participants. Participants in the 18- to 24-month-old age group provided significantly more threshold estimates with insert earphones (mean = 5.3 threshold estimates, SD = 3.5) than with supra-aural earphones (mean = 2.9 threshold estimates, SD = 2.9). All seven participants who rejected earphone placement were successfully reconditioned for soundfield testing.
CONCLUSIONS: Data support the use of insert earphones during VRA, especially with 18-to 24-month-old children, to obtain ear-specific information.

PMID: 26903087 [PubMed - as supplied by publisher]

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