Abstract
Lexical bias is the tendency to perceive an ambiguous speech sound as a phoneme completing a word; more
ambiguity typically causes greater reliance on lexical knowledge. A speech sound ambiguous between /g/ and /k/ is
more likely to be perceived as /g/ before /Ift/ and as /k/ before /Is/. The magnitude of this difference—the Ganong
shift—increases when high cognitive load limits available processing resources. The effects of stimulus naturalness
and informational masking on Ganong shifts and reaction times were explored. Tokens between /gI/ and /kI/ were
generated using morphing software, from which two continua were created (“giss”–“kiss” and “gift”–“kift”). In
experiment 1, Ganong shifts were considerably larger for sine- than noise-vocoded versions of these continua, presumably because the spectral sparsity and unnatural timbre of the former increased cognitive load. In experiment 2,
noise-vocoded stimuli were presented alone or accompanied by contralateral interferers with constant within-band
amplitude envelope, or within-band envelope variation that was the same or different across bands. The latter, with
its implied spectro-temporal variation, was predicted to cause the greatest cognitive load. Reaction-time measures
matched this prediction; Ganong shifts showed some evidence of greater lexical bias for frequency-varying interferers, but were influenced by context effects and diminished over time.
ambiguity typically causes greater reliance on lexical knowledge. A speech sound ambiguous between /g/ and /k/ is
more likely to be perceived as /g/ before /Ift/ and as /k/ before /Is/. The magnitude of this difference—the Ganong
shift—increases when high cognitive load limits available processing resources. The effects of stimulus naturalness
and informational masking on Ganong shifts and reaction times were explored. Tokens between /gI/ and /kI/ were
generated using morphing software, from which two continua were created (“giss”–“kiss” and “gift”–“kift”). In
experiment 1, Ganong shifts were considerably larger for sine- than noise-vocoded versions of these continua, presumably because the spectral sparsity and unnatural timbre of the former increased cognitive load. In experiment 2,
noise-vocoded stimuli were presented alone or accompanied by contralateral interferers with constant within-band
amplitude envelope, or within-band envelope variation that was the same or different across bands. The latter, with
its implied spectro-temporal variation, was predicted to cause the greatest cognitive load. Reaction-time measures
matched this prediction; Ganong shifts showed some evidence of greater lexical bias for frequency-varying interferers, but were influenced by context effects and diminished over time.
| Original language | English |
|---|---|
| Pages (from-to) | 3369-3386 |
| Number of pages | 18 |
| Journal | Journal of the Acoustical Society of America |
| Volume | 151 |
| Issue number | 5 |
| DOIs | |
| Publication status | Published - 23 May 2022 |
Bibliographical note
© 2022 Author(s). All article content, except where otherwise noted, is licensed under a Creative CommonsAttribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
Funding: This research was supported by Research Grant ES/N014383/1 from the Economic and Social Research Council
(UK), awarded to Brian Roberts