Feasibility of an “Alien Language” Task for Prosody Assessment in Children With Down Syndrome

Abstract

Prosodic impairments are reported in children with Down syndrome (DS), yet current assessment tools often impose cognitive and linguistic demands that potentially obscure true prosodic ability. There is a need for accessible, low–verbal-load tasks to evaluate prosody in this population and other populations with limited verbal abilities. This proof-of-concept pilot study examines the feasibility and construct validity of an “Alien Language” task designed to elicit prosodic variation through imitation of nonlexical syllable strings under different pragmatic conditions. Five children with DS completed a novel prosody task named “Alien Language” task involving repetition of consonant–vowel syllables produced as statements or questions or with emphatic stress. Acoustic measures of fundamental frequency ( F 0) and mean duration were extracted. Generalized additive mixed models (GAMMs) were applied to F 0 contours to assess condition-dependent prosodic variation and individual differences in intonation. The task elicited systematic acoustic variation across conditions. Descriptive analyses showed higher F 0 and longer durations in emphatic and sequential conditions. GAMM results revealed significant time-varying effects for specific conditions and robust participant-level variation in F 0 trajectories. While most pairwise contrasts were not statistically significant in this feasibility study, patterns suggested sensitivity to subtle prosodic modulation. The “Alien Language” task appears to be a feasible approach for eliciting analyzable prosodic variation in children with DS. It enables evaluation of F 0 variation without lexical confounds and may serve as a foundation for future clinical and developmental prosody research. Further validation in larger samples is warranted.