Research method for the study of intonation

Shunsuke NAKATA

1.       Three levels of analysis

At the study of speech communication, three levels of analysis can be distinguished, that is, linguistic, perceptual and acoustic ones. It means that the research of speech sound can be made possible only within the limits of acoustical and perceptual experiments.

2.       Linguistic level

1) Data of informants Date of informants, such as their age ,sex, origin, profession can be obtained by questionnaires. Generally, to raise the statistical reliability of the data, the number of the informants should be augmented.

2) Type of speech materials To analyse the communicative value of intonation, the 都pontaneous conversation will best be used, but other authentic documents such as radio or TV recordings have often been preferred in order to reduce the complexity of discourse structure. Researches which treat exclusively the so-called neutral intonation to analyse its syntactic function restrain their materials to texts or sentences read out.

3) Number and volume of speech materials It is generally recommended to prepare plural corpora of almost the same volume. The number and the volume of speech materials should be determined according to the purpose of the analysis.

3.       Perceptual level

Intonation can be described as complex patterns of three acoustical parameters, i.e. F0 , intensity and duration. In modelling intonation, several pitch levels are preliminally determined, which have to be validated by perceptual experiments. Actually, it is confirmed that not all the pitch movements are linguistically pertinent.

4.       Acoustical level

Digital analysis of speech sound has structural limits as below. It need to be controled according to the caracteristics of materials and to the the purpose of the investigation.

Extraction of F0 : Trade-off between time and frequency resolution

Measurement of duration : Difference between potential and effective resolution

Measurement of intensity : Trade-off between time and amplitude resolution, S/N ratio