Hong-Ying Zheng

The influence of language experience on categorical perception of pitch contours

Previous research on categorical perception of pitch contours has mainly considered the contrast between tone language and non-tone language listeners. This study investigates not only the influence of tone language vs. non-tone language experience (German vs. Chinese), but also the influence of different tone inventories (Mandarin tones vs. Cantonese tones), on the categorical perception of pitch contours. The results show that the positions of the identification boundaries do not differ significantly across the 3 groups of listeners, i.e., Mandarin, Cantonese, and German, but that the boundary widths do differ significantly between tone language (Mandarin and Cantonese) listeners and non-tone language (German) listeners, with broader boundary widths for non-tone language listeners. In the discrimination tasks, the German listeners exhibit only psychophysical boundaries, whereas Chinese listeners exhibit linguistic boundaries, and these linguistic boundaries are further shaped by the different tone inventories.

The impact of tone systems on the categorical perception of lexical tones: An event-related potentials study

This study investigates the categorical perception (CP) of pitch contours (level and rising) by native listeners of two tone languages, Mandarin and Cantonese, for both speech and nonspeech. Language background was found to modulate participants’ behavioural and electrophysiological responses to stimuli presented in an active oddball paradigm, comprising a standard and two equally spaced deviants (within- and across-category). The stimuli were divided into two sets according to the results of a two-alternative forced-choice identification test: a rising set, using a standard that listeners identified as high rising tone, and a level set, using a standard that listeners identified as high level tone. For the rising set, both groups of listeners exhibited CP in terms of their behavioural response. However, only Cantonese listeners exhibited a significant CP effect in terms of P300 amplitude. For the level set, the behavioural data revealed a shift in category boundary due, in part, to the range–frequency effect. According to the d′ scores, the CP effect elicited from Mandarin listeners was greater for nonspeech stimuli than for speech, suggesting the presence of apsychophysical boundary. There was no such behavioural contrast for Cantonese listeners. However, Cantonese listeners exhibited a significant CP effect in P300 amplitude that was influenced by the range–frequency effect, as well as a possible secondary phonological boundary. P300 amplitude is believed to index the ease of discrimination of speech stimuli by phonological information. We conclude that Cantonese listeners engaged phonological processing in order to discriminate speech stimuli more efficiently than Mandarin listeners. These findings may be due to the different tonal inventories of Mandarin and Cantonese, with Cantonese listeners required to make finer distinctions in perception of pitch height and slope than Mandarin listeners in order to discriminate the denser tone system of Cantonese.

A Chinese Text Input Brain-Computer Interface Based on the P300 Speller

A visual speller is a brain–computer interface that empowers users with limited motor functionality to input text into a computer by measuring their electroencephalographic responses to visual stimuli. Most prior research on visual spellers has focused on input of alphabetic text. Adapting a speller for other types of segmental or syllabic script is straightforward because such scripts comprise sufficiently few characters that they may all be displayed to the user simultaneously. Logographic scripts, such as Chinese hanzi, however, impose a challenge: How should the thousands of Chinese characters be displayed to the user? Here, we present a visual speller, based on Farwell and Donchins P300 Speller, for Chinese character input. The speller uses a novel shape-based method called the First–Last, or FLAST, method to encode more than 7,000 Chinese characters. Characters are input by selecting two components, from a set of 56 distinct components, that match the shape of the target character, followed by selection of the character itself. At the input speed of one character per 107 s, 24 able-bodied participants achieved mean online accuracy of 82.8% per component selection and 63.5% per character input. At the faster input speed of one character per 77 s, mean online accuracy was 59.4% per component selection and 33.3% per character input.

An Assistive Communication Brain-Computer Interface for Chinese Text Input

The performance of assistive communication brain-computer interfaces has been studied mostly for languages with alphabetic script. The viability of using such systems for languages with other types of script, such as Chinese, which has a logographic script, is currently poorly understood. Here, a performance analysis of the P300 Speller is presented for Chinese text input. The performance of six distinct paradigms, based on the established Row/Column (RC) and Single Character (SC) spellers, are tested and compared for 30 able-bodied, native Chinese readers. In terms of accuracy per trial, the optimal paradigm is based on the SC speller: 63.3% of participants were able to achieve 80% or better classification accuracy for 15 trials. However, because the RC speller has shorter trial duration than the SC speller, the optimal paradigm in terms of communication rate is a variant of the RC speller in which stimuli are intensified by changing background color. A communication rate of 14.5 bits per minute was attained using this paradigm. For a lexicon of ~11,000 Chinese characters, this corresponds to a projected mean input rate of ~1.1 characters per minute.

Tone recognition for Chinese speech: a comparative study of Mandarin and Cantonese

The paper presents a comparative study on automatic continuous tone recognition for Mandarin and Cantonese. Compared with Mandarin, Cantonese has a much more complex tone system. The effects of F/sub 0/ normalization on the tone recognition of Mandarin and Cantonese are studied. Furthermore, the two tone systems are compared from an engineering point of view. Tone recognition accuracies of 71.50% and 83.06% have been obtained for Cantonese and Mandarin respectively. These results compare favorably with results reported for other tone recognition experiments on the same (for Cantonese) and similar (for Mandarin) databases.