Аннотация:Tones have frequently appeared and multiplied under the influence of the laryngeal articulations of adjacent consonants (§2–§4), but much more rarely under the influence of the vowels that bear them (§6). The laryngeal articulations of following consonants readily introduce tones into previously toneless languages, but those of preceding consonants far more often split existing tones than introduce them where there were none before (§5). Opposite tones can arise from the same ostensible phonological source, apparently because the source can be pronounced so as to raise or lower F0 (§3.2.2 and §4). Finally, tone can arise from prosodic as well as segmental sources (§7). In all these sound changes, a predictable or redundant F0 difference becomes contrastive – i.e. is “phonologized” – once the contrast that introduced it neutralizes. These changes show how easily languages blur the distinction between phonetics and phonology and undermine their autonomy over time.
