Sensitivity of envelope following responses to vowel polarity.

Sensitivity of envelope following responses to vowel polarity.
Hear Res. 2014 Dec 8;
Authors: Easwar V, Beamish L, Aiken S, Choi JM, Scollie S, Purcell D
Abstract
Envelope following responses (EFRs) elicited by stimuli of opposite polarities are often averaged due to their insensitivity to polarity when elicited by amplitude modulated tones. A recent report illustrates that individuals exhibit varying degrees of polarity-sensitive differences in EFR amplitude when elicited by vowel stimuli (Aiken and Purcell, 2013). The aims of the current study were to evaluate the incidence and degree of polarity-sensitive differences in EFRs recorded in a large group of individuals, and to examine potential factors influencing the polarity-sensitive nature of EFRs. In Experiment I of the present study, we evaluated the incidence and degree of polarity-sensitive differences in EFR amplitude in a group of 39 participants. EFRs were elicited by opposite polarities of the vowel/ε/in a natural/hVd/context presented at 80 dB SPL. Nearly 30% of the participants with detectable responses (n = 24) showed a difference of greater than ∼ 39 nV in EFR response amplitude between the two polarities, that was unexplained by variations in noise estimates. In Experiment II, we evaluated the effect of vowel, frequency of harmonics and presence of the first harmonic (h1) on the polarity sensitivity of EFRs in 20 participants with normal hearing. For vowels/u/,/a/a...

Source: Hearing Research - December 8, 2014 Category: Audiology Authors: Easwar V, Beamish L, Aiken S, Choi JM, Scollie S, Purcell D Tags: Hear Res Source Type: research