Representing Tone in Levenshtein Distance

Levenshtein distance, also known as string edit distance, has been shown to correlate strongly with both perceived distance and intelligibility in various Indo-European languages ( Gooskens and Heeringa, 2004 ; Gooskens, 2006 ). We apply Levenshtein distance to dialect data from Bai ( Allen, 2004 ), a Sino-Tibetan language, and Hongshuihe (HSH) Zhuang (Castro and Hansen, accepted), a Tai language. In applying Levenshtein distance to languages with contour tone systems, we ask the following questions: 1) How much variation in intelligibility can tone alone explain? and 2) Which representation of tone results in the Levenshtein distance that shows the strongest correlation with intelligibility test results? This research evaluates six representations of tone: onset, contour and offset; onset and contour only; contour and offset only; target approximation ( Xu & Wang, 2001 ), autosegments of H and L, and Chao's (1930) pitch numbers. For both languages, the more fully explicit onset-contour-offset and onset-contour representations showed significantly stronger inverse correlations with intelligibility. This suggests that, for cross-dialectal listeners, the optimal representation of tone in Levenshtein distance should be at a phonetically explicit level and include information on both onset and contour.

Gamma-Band Responses to Perturbed Auditory Sequences: Evidence for Synchronization of Perceptual Processes

We measured modulations of neuroelectric gamma-band activity (GBA) as subjects listened to isochronous pure-tone sequences with embedded temporal perturbations. Perturbations occurred every 6�10 tones, and at the locus of the perturbation, tones occurred early, on time, or late. In the absence of perturbations, induced (non�phase-locked) GBA reached maximum power simultaneously with the occurrence of tone onsets, whereas evoked (phase-locked) GBA peaks were observed after onsets. During late perturbation trials, peaks in induced activity tended to precede tone onsets, and during early perturbation trials, induced peaks followed tone onsets. Induced peaks returned to synchrony after both types of perturbations. Early tones resulted in a marked increase in evoked GBA power at the locus of the perturbation. The latency of evoked GBA relative to tone onset, as well as some other features of the response, depended asymmetrically on the direction of the perturbation. The current results provide evidence for the synchronization of GBA during the perception of auditory rhythms, thus supporting the role of GBA in temporal expectancy.

Rate Limits of On-Beat and Off-Beat Tapping With Simple Auditory Rhythms: 1. Qualitative Observations

The accuracy of on-beat and off-beat synchronized finger tapping was examined as a function of sequence rate in musically trained individuals. Auditory sequences consisted of cyclically repeated, underlyingly isochronous patterns of the form T0, TT0, or TTT0, where T denotes a tone onset and 0 denotes its absence. In different conditions, participants attempted to tap in synchrony with one of the possible T (�on-beat�) or 0 (�off-beat�) positions in each pattern while the sequence rate increased from trial to trial. It was hypothesized that on-beat tapping would be easier with tones that carry a rhythmic grouping accent (T2 in TT0, T1 and T3 in TTT0) than with tones that do not (T1 in TT0, T2 in TTT0), according to findings of Povel and colleagues. The hypothesis was strongly supported for TTT0, but there were considerable individual differences with regard to TT0. Off-beat tapping was generally difficult and often switched to on-beat tapping at fast tempi. The findings reveal rate limits of sensorimotor coordination that may be relevant to music performance in ensembles.