Speech characteristics of monozygotic twins and a same-sex sibling: an acoustic case study of coarticulation patterns in read speech.

This case study reports on an acoustic investigation of the motor speech characteristics of a set of young adult male monozygotic (MZ) twins and compares them to those of an age- and sex-matched sibling who participated in the study 2 years later to match for demographic factors. Coarticulation patterns were investigated from read samples of consonant-vowel sequences in monosyllabic words containing a variety of consonants and vowels. This was done by examining F(2) vowel onsets and F(2) vowel targets, plotted as F(2) locus equations. Data were processed for between-sibling differences using a number of statistical tests. Results indicated that the MZ twins displayed F(2) parameters and coarticulation patterns which were more similar than those of their age- and sex-matched sibling. The results of this case study therefore suggest that acoustic phonetic parameters used to index coarticulation patterns have the potential to profile some of the similarities and differences in the speech characteristics of genetically related individuals.