Octave-shifted pitch matching in nonword imitations: the effects of lexical stress and speech sound disorder.

Perceptual similarities of musical tones separated by octave intervals are known as octave equivalence (OE). Peter et al. [(2008). Proceedings of the Fourth Conference on Speech Prosody, edited S. Maduerira, C. Reis, and P. Barbosa, Luso-Brazilian Association of Speech Sciences, Campinas, pp. 731-734] found evidence of octave-shifted pitch matching (OSPM) in children during verbal imitation tasks, implying OE in speech tokens. This study evaluated the role of lexical stress and speech sound disorder (SSD) in OSPM. Eleven children with SSD and 11 controls imitated low-pitched nonwords. Stimulus/response f(0) ratios were computed. OSPM was expressed preferentially in stressed vowels. SSD was associated with reduced expression of OSPM in unstressed vowels only. Results are consistent with the psycholinguistic prominence of lexical stress and prosodic deficits in SSD.