Modelling the perception of English F 0 scaling in a segmental context
Segmental context in tone and intonation systems is known to influence target F0 contours in both production and perception. Many languages, for example, prefer to realize critical F0 events during maximally sonorous intervals, a tendency manifest variously through altered pitch movement timing [3] [15] [14] [11] and in distributional limitations on certain contour types [6] Current analytic practice, by contrast, routinely ignores segmental backdrop when considering the perceptual efficacy of putative pitch cues such as F0 turning points: Tone scaling is typically equated simply with measured turning point height, while tonal timing is read directly off turning points, whose salience is estimated visually, rather than auditorily. Even voiceless intervals may receive no special treatment, owing to widespread belief in perceptual completion during missing F0 intervals [13] [7] a process modelled explicitly in many stylization algorithms (e.g. MOMEL, [8] [1] however, cast doubt on this, demonstrating that listeners' tone scaling judgments are better understood by ignoring F0 gaps, relying instead solely on recorded F0 values. This study goes further, arguing that the perceptual effects of a range of lower sonority segments require a scaling model based not on single points, but instead on the integration of weighted F0 samples over a broader region [4] In a 2AFC task, listeners judged the relative scaling of two L+H* accents, realized during versions of the English words day, Dane, Dave, and Dade, resynthesized with identical rhyme durations, nucleus:coda ratios (where relevant) and F0 rises (150 Hz at rhyme onset to 200 at offset) A carrier phrase, X might fit, bore a rise fall rise contour, with nuclear accent on X. Seven additional versions of each stimulus phrase were also created, these with high, plateau shaped accents, beginning at 200 Hz, and descending by .5 semitones/step, to create a continuum of level reference standards. Sharp peaked test stimuli were compared only with reference standards of identical segmental make up (Figures 1a d) Since plateau shaped accents are known to sound higher than sharp peaked analogues with identical maximum F0 [5] [10] sharp peaked stimuli should sound somewhat lower than their highest corresponding reference levels, with 50% crossover points within the continuum providing estimates of perceived F0 for each sharp peaked accent. Identical perceived scaling for test stimuli regardless of segmental make up would predict identical response patterns for all syllable types. This was not the case for 35 listeners (Fig 2) analyzed using mixed effects logistic regression. Instead, subjects heard day as highest, followed by Dane, then Dave, with Dade