Experimental phonetics

stressed vs. unstressed vowels, (d) Formant frequency (F2) stressed vs.

unstressed vowels, and (e) Formant frequency of stressed vs. unstressed vowels.

Impressionistic phonetics focusses on the positions and movements of the speech organs involved in the production of individual speech sounds. It is based on a number of assumptions about the nature of speech. Important among these are:

1. Speech can be represented as a series of segments.

2. Each segment has a target, and can be specifie uniquely with reference to its target. Each target corresponds to a unique auditory percept in the mind of a trained observer.

3. Any segmental target can be specified using a limited number of dimensions. These dimensions do not need to be defined for each language individually. Instead, there is a universal set of dimensions which are relevant to all human languages. For example, the English word fan might be represented as [fæn].1 This implies that it is made up of a sequence of three segments, as, indeed, is suggested by the spelling. Let us now focus our attention on the first segment, represented by the letter f. It is produced by forcing air through a narrow opening between the lower lip and the upper teeth. The target may be described as: 'loose contact between lower lip and upper teeth, vocal folds open and not vibrating', and is conventionally specified as a voiceless labiodental fricative. Each term of this three-term label refers to one articulatory dimension.