Acoustic correlates for perceived effort levels in male and female acted voices.

The best actors, particularly classic Shakespearian actors, are experts at vocal expression. With prosodic inflection, change of voice quality, and non-textual utterances, they communicate emotion, emphasize ideas, create drama, and form a complementary language which works with the text to tell the story in the script. To begin to study selected elements of vocal expression in acted speech, corpora were curated from male actors' Hamlet and female actresses' Lady Macbeth soliloquy performances. L1 speakers of American English on Mechanical Turk listened to excerpts from the corpora, and provided descriptions of the speaker's vocal expression. In this exploratory, open-ended, mixed-methods study, approximately 60% of all responses described emotion, and the remainder of responses split evenly between voice quality (including effort levels) and prosody. Also, significant differences were found in the kind and quantity of descriptors applied to male and female speech. Perception-grounded male and female acoustic feature sets which tracked the actors' expressive effort levels through the continuum of whispered, breathy, modal, and resonant speech are presented and validated via multiple models. The best results in applying these features to simple, un-optimized, four-way decision tree classifiers yielded 76% accuracy for male and 73% accuracy for female expressive, acted speech.