Efficiency as an organizing principle of natural speech

A large part of the variation in natural speech appears along the dimensions of articulatory precision / perceptual distinctiveness. We propose that this variation is the result of an effort to communicate efficiently. Speaking i s considered efficient if the speech sound contains only the information needed to understand it. This efficiency is tested by means of a corpus of spontaneous and matched read speech, and syllable and word frequencies as measures of information content (12007 syllables, 8046 word forms, 1582 intervocalic consonants, and 2540 vowels). It is indeed found that the duration and spectral reduction of consonants and vowels correlate with the frequency of syllables and words in this corpus. Consonant intelligibility correlates with both the acoustic factors and the syllable and word frequencies. It i s concluded that the principle of efficient communication organizes at least some aspects of speech production.