The effect of number of perceptual categories on identification functions of non-speech stimuli and the relationship to categorization of Hebrew voicing.
Category boundary (CB) of Hebrew voicing on voice-onset time (VOT) continuum was found to be different from non-speech stimuli on tone-onset time (TOT) continuum. This is in contrast to data in English, thus suggesting that CB for speech stimuli may be determined not only by general auditory sensitivities but by additional factors that may be speech specific. The data in Hebrew voicing, however, can also be explained by the fact that in Hebrew voicing, two categories were available to the listener, whereas for the TOT stimuli there were three: leading, simultaneous and lagging temporal events. The purpose of the present study was to investigate the effect of number of perceptual categories on CB of non-speech analogs of voicing in Hebrew-speaking subjects and compare them to those obtained on a VOT continuum. Twenty-four Hebrew-speaking adults participated in this study. Stimuli consisted of (a) a two-tone complex continuum that varied in the relative onset time of the lower frequency tone, and (b) a /ba-pa/ continuum which varied in VOT values similar to (a). The same TOT continuum was tested twice. In one, subjects identified TOT stimuli as belonging to one of three categories (TOT3): leading, simultaneous, or lagging; and in the other to two categories of TOT (TOT2): leading or lagging. VOT stimuli were labeled as /ba/ or /pa/. Results show that (1) when listeners were offered only two perceptual categories of temporal events, the pattern of identification functions matched one of the two functions shown for TOT3, and (2) the category boundary of VOT stimuli was similar for all subjects regarding the value calculated for TOT2. The present study supports the hypotheses that (1) CB of non-speech stimuli is not influenced by the number of perceptual categories available to the listener, and (2) different mechanisms may underlie the categorical perception of speech versus non-speech stimuli.
Kishon-Rabin
Liat
L
Department of Communication Disorders, Sackler Faculty of Medicine, Tel Aviv University, Israel. lrabin@post.tau.ac.il
Kochva
Rotem
R
Kigel
Sharon
S
Rotshtein
Shira
S
Roth
Daphne Ari-Even
DA
D000161:Acoustic Stimulation; D000328:Adult; D001307:Auditory Perception / Q000502:physiology*; D005260:Female; D006801:Humans; D007802:Language; D010700:Phonetics; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D013067:Speech Perception / Q000502:physiology; D014831:Voice / Q000502:physiology*