Acoustic Realization of Singleton–Geminate Contrast in Lebanese Arabic Infant-Directed Speech: A Case Study

Although Infant-directed speech (IDS) involves modifications of speech to facilitate child’s language acquisition, this area of research needs more evidence on the maintenance of segmental contrasts. Drawing on a longitudinal corpus of conversation recordings of a Lebanese mother and her young son over eight months at Newcastle University, this acoustic study examined IDS with a focus on Lebanese Arabic (LA). It analyzed single and double coronal consonants (C) in two-and three-syllable trochaic words with short vowels (V). Using PRAAT-based acoustic analysis, 560 tokens of trochaic disyllabic and trisyllabic words in short-V contexts were examined for duration, intensity, and fundamental frequency (F0). Descriptively, results showed that duration is the primary cue distinguishing singleton and geminate coronals, while intensity serves as a secondary cue; F0 does not differentiate the contrast in IDS. In IDS, F0 did not serve as a reliable cue for identifying geminate from singleton Cs, unlike adult-directed speech in LA. These findings suggest that, in the present case, IDS maintains durational contrasts but downplays pitch cues. This contributes to broader discussions of how infants encounter phonetic structure in caregiver speech and how such input may shape the acquisition of contrastive C length.