ACOUSTIC ADAPTATION AND METABOLIC COST: A Unified Biophysical Framework for Phonetic Morphology

This study proposes a unified biophysical framework to investigate cross-linguistic variation in phonetic morphology, integrating two complementary mechanisms: acoustic adaptation to atmospheric transmission and metabolic cost minimization in speech production. The framework explores how the sonority ratio and syllabic rate of a language are constrained by frequency-dependent atmospheric absorption (determined by temperature and humidity) and the energetic expenditure required for speech. Preliminary exploratory analysis using PHOIBLE and LAPSYD datasets suggests patterns consistent with the proposed mechanism. Note: This is a preprint shared to ensure the immediate availability of the proposed framework while it awaits the formal peer-review cycle (slated for consideration by the Finnish Journal of Linguistics, January 2027).