A Chimpanzee Recognizes Synthetic Speech with Significantly Reduced Acoustic Cues to Phonetic Content

A long-standing debate concerns whether humans are specialized for speech perception [1,2,3,4,5,6,7], which some researchers argue is demonstrated by the ability to understand synthetic speech with significantly reduced acoustic cues to phonetic content [2,3,4,7]. We tested a chimpanzee (Pan troglodytes) that recognizes 128 spoken words [8,9], asking whether she could understand such speech. Three experiments presented 48 individual words, with the animal selecting a corresponding visuographic symbol from among four alternatives. Experiment 1 tested spectrally reduced, noise-vocoded (NV) synthesis, originally developed to simulate input received by human cochlear-implant users [10]. Experiment 2 tested impossibly unspeechlike [3] sine-wave (SW) synthesis, which reduces speech to just three moving tones [11]. Although receiving only intermittent and noncontingent reward, the chimpanzee performed well above chance level, including when hearing synthetic versions for the first time. Recognition of SW words was least accurate but improved in experiment 3 when natural words in the same session were rewarded. The chimpanzee was more accurate with NV than SW versions, as were 32 human participants hearing these items. The chimpanzee’s ability to spontaneously recognize acoustically reduced synthetic words suggests that experience rather than specialization is critical for speech-perception capabilities that some have suggested are uniquely human [12,13,14].

from Current Biology


About Callier Library

Housed at the internationally renowned Callier Center for Communication Disorders, Callier Library a branch facility of the McDermott Library at The University of Texas at Dallas.

Posted on July 26, 2011, in Research. Bookmark the permalink. Leave a comment.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

%d bloggers like this: