Published online by Cambridge University Press: 18 February 2010
Inevitably, the more intonation contrasts a language has, the harder it is to maintain a system of lexical tone contrasts, and vice versa. West Germanic languages have a large number of intonation contrasts, and so, a priori, the introduction of a lexical tone contrast in one of those languages should be problematic. Essentially, this would double the number of required contrasts, since every intonation pattern will have to be usable on words from two tonal word classes. The language is likely to respond to this situation by reducing the number of intonation contours; by enhancing pitch contrasts by means of other phonetic parameters, like duration or vowel quality; or, if all else fails, by banning certain forms that would otherwise be too similar to other forms, or be particularly hard to pronounce. In the last case, forms that are generated by the grammar are simply not used. We may well regret that we cannot artificially introduce a tone contrast in a West Germanic language to see what will happen, but here is the good news: a lexical tone developed quite spontaneously in the Central Franconian dialect of German, probably around 1300. The novel feature spread, probably from Cologne, as far south as Luxembourg and and as far west as Hasselt (Belgium) and Maastricht (the Netherlands). The tonal area must have been larger than it is now, but it still measures some 160 km north-to-south and 125 km east-to-west (Schmidt 1986; de Vaan 1999), covering four countries in the Dutch–German dialect continuum.