Some lengthening factors in English speech combine additively at most rates

The known lengthening effects of phrase-final position and of contrastive e mphasis have been predicted by Klatt to combine superadditively. In a new e xperiment, texts elicited at a wide range of speaking rates were measured a nd the separate and combined effects of these lengthening factors were foun d to combine approximately additively at all rates studied. The proportion of lengthening attributable to each factor was found to be relatively invar iant except at the fastest speaking rates, where lengthening was eventually eliminated. The results support the interpretation of absolute speaking ra te as an inessential Variable for characterizing speech at a range of moder ate rates. (C) 1999 Acoustical Society of America. [S0001-4966(99)00801-2].