Sound level protrusions as physical correlates of sonority

A long-standing controversy in the interface between phonetics and phonology involves the nature of sonority: does it even exist and, if so, what are its phonetic correlates, and how can this be empirically demonstrated? This paper seeks to help resolve this problem by providing physical evidence supporting the sonority hierarchy. This is accomplished by reporting the results of a rigorous experiment measuring sound levels of realizations of all phonemes in English, Spanish, and Quechua. The obtained intensity values yield an overall mean Spearman's correlation of .91 with the proposed sonority indices. Consequently, one possible way to informally characterize sonority is in terms of a linear regression equation based on the observed intensity results. In light of these findings, the frequent claim that sonority lacks a reliable phonetic basis can no longer be maintained.