Aeroacoustic consequences of tongue troughs in labiodentals

It has long been accepted that the main constriction for fricatives /f, v/ is formed by the lower lip pressing against the upper teeth, thus allowing the tongue to freely coarticulate with preceding and following segments. Here, electromagnetic articulometry data were obtained from 5 subjects in a study of tongue troughs, defined as a discontinuity in anticipatory coarticulation, such as when the tongue drops during a bilabial consonant in /ii/ context. The corpus included /f/ and /v/ in VC(C)V contexts, where V = /i/ for C= /v/, and V = {/i a u/} for C= /f/. The tongue moved down and back for /f/ in all vowel contexts; in /iC(C)i/ context, the troughs were deeper for long (VCCV) than short labial consonants, as predicted, and deeper for /f/ than for /p, b, v, m/, which was unexpected. There seems to be a secondary gesture specifying that the tongue be down during labiodental fricatives. Our hypothesis is that lowering the tongue for /f/ ensures that the airflow resistance will be due only to the labioden...