Acoustic characteristics of monophthong realisation in Southern Standard Dutch

0. Introduction The vowel system of Southern Standard Dutch in Flanders consists of 12 vowels which can be distinguished on the basis of three articulatory dimensions. The degree of opening of vowels (closed vs. open) correlates with the degree of constriction of the vocal tract, while a distinction can be made between front, mid and back vowels on the basis of place of articulation. This vertical and horizontal classification combines with the dimension of lip rounding. All vowels in the Flanders area are monophthongs and this is one of the main pronunciation differences with Northern Standard Dutch. Vowel systems in languages of the world differ considerably in terms of the number of vowel qualities. According to Maddieson (1984) the number of vowels varies between 3 and 15 with 5 vowels being the most frequently observed system. The vowel system of standard Dutch in Flanders can thus be regarded as relatively dense. From an acoustic point of view vowels have a clear formant structure. It is generally assumed that F1 and F2 are most relevant for a vowel’s identity. The relationship between vowel acoustics and vowel articulation is by no means a simple matter, but is accepted that F1 mainly correlates with articulatory degree of opening, while F2 reflects place of articulation. Besides vowel identity, the acoustic structure of vowels also contains speaker-related information such as anatomical differences between speakers: “(...) some speakers with big heads will have large resonating cavities, producing formants with comparatively low frequencies; and other will have higher formant frequencies because they have smaller vocal tracts.” (Ladefoged, 2001: 39). This is clear in comparisons of vowels produced by men and women. Since men’s vocal tracts are generally bigger than women’s, formant values of vowels tend to be lower in men. Another source of speaker-related information is a speaker’s habitual articulatory setting. This is defined in Laver (1994) as “any co-ordinatory tendency underlying the production of the chain of segments in speech towards maintaining a particular configuration or state of the vocal apparatus” (p. 396). The habitual setting of individual speakers can differ and this may influence the acoustic characteristics of vowels. A palatal setting will clearly influence the realisation of open back vowels, while a velar