Fig 1.
Time waveform and average amplitude-envelope of the word /pæk/.
The top panel shows the original waveform, without level increments; the center panel shows the same waveform with a 6.0 dB increment in the RMS level of the post-vocalic stop-consonant burst. Vertical lines show the boundaries between four segments defined in the syllable. In the bottom panel, the abscissa shows the average duration (ms) of the four segments delimited on each CvC word: pre-vocalic burst (Cv), vowel (v), silence, and post-vocalic burst (vC). The ordinate shows the average peak dB SPL of each segment, highlighting the level relation between the noise-burst target and the vowel masker. Dashed horizontal lines depict the level increment (∆L) in the stop-consonant noise-burst target.
Fig 2.
Psychometric functions relating discrimination accuracy to the burst level increment.
In Fig 2, the correct probability, P(C), as a function of ∆L in dB is shown for each of 9 participants (one per row) listening to ∆L in the pre-vocalic burst of /pæk/ presented in isolation or in /pæk/ context (1st & 2nd column on the left-hand side). Smooth curves are maximum-likelihood probits that come closest to the data points. In the same format, the 3rd and 4th column on the right side show functions for ∆L in the post-vocalic burst presented in isolation or embedded in /pæk/. See Supporting Information S1 Fig for further details.
Fig 3.
Level Discrimination Thresholds (LDTs).
The LDTs (Y axis) measured in experiment 1 with the words /pæk/ and /pæt/ are depicted in the top (A) and middle panels (B), respectively; the bottom panels (C) depict the LDTs measured in experiment 2. Panels on the left- and right-hand side depict LDTs estimated at the 0.75 and 0.85 correct probability, respectively. In the top panels, for level increments in the pre-vocalic (Cv) burst of /pæk/, bars labeled PC and PI depict average LDTs (ordinate) for Cv in context and Cv in isolation; for level increments in the post-vocalic (vC) burst of /pæk/, bars labeled KC and KI depict the LDTs for vC in context and vC in isolation. For ease of comparison, on the left-hand side panels, the dashed horizontal lines depict the LDT for level increments encompassing the entire CvC word measured by [8]; since this LDT was estimated only at a correct probability of 0.71, it is not included in the right-hand side panels. In all panels, error bars depict 1.0 standard error below the mean. Middle panels (B): for level increments in the pre-vocalic (Cv) burst of the word /pæt/, bars labeled PC and PI depict average LDTs (Y axis) for Cv in context and Cv in isolation; for level increments in the post-vocalic (vC) burst, bars labeled TC and TI depict the corresponding thresholds for vC in context and vC in isolation. Bars labeled PC+T and TC+P depict LDTs measured in the word-context condition that interleaved level increments in the pre- (Cv) or post-vocalic (vC) burst within each trial block (temporal-position variability). Bottom panels (C): for level increments in the pre-vocalic (Cv) burst of /kæt/, /pæt/, or /pæk/, bars labeled CAT-K, PAT-P and PACK-P depict average LDTs (Y axis) for Cv in context; bars labeled CAT-T, PAT-T, and PACK-K depict the corresponding LDTs for level increments in the post-vocalic burst (vC). Since all six conditions were interleaved within each trial block, the task included variability in the temporal position of the level increment and in the consonant place of articulation. See Supporting Information S2 Fig for further details.