Humans hear and understand language through a staggering number of filters — language is heard coming out of the unique voice boxes and accents of millions of our peers, compressed by cell phones, radios, televisions, and computers, and mumbled in rock songs, yet we still manage to understand it through all the noise.
One of many defenses of the theory that spoken language is, essentially, a “human-specific” adaptation, rather than a more subtle evolution of earlier mamallian precursors, points to our ability to understand language in such a multitude of different situations; after it is mangled, processed, and distorted. How else can we explain these feats than by assuming that we’re specialized for spoken language?
Some interesting new research by Lisa Heimbauer and her team at Georgia State University challenges this argument. They’ve shown that chimpanzees raised hearing and responding to a vocabulary (albeit, a small one) of human language are able to understand words even after they scarcely resemble their natural, human intonations. [ The chimps were said to “understand” words and sentences because they could correctly point to corresponding lexigrams when they heard spoken sentences – the main chimp subject, Panzee, has a vocabulary of 128 English words].
Using two techniques that drastically reduced the natural, human-like acoustics of the chimps’ lexicon (hear an example here), the researchers were able to test the chimpanzees’ ability to understand low-fi English. Incredibly, the chimps correctly distinguished the distorted words at a rate comparable to humans.
There are some important limits of this study: The subjects have a relatively tiny vocabulary when compared to that of humans (128 vs. 40,000), they can not necessarily be said to “understand” the words in the same textured way as humans, and the work only refers to rigorously trained individuals rather than wild chimps. However, the research does show that chimps do have the necessary neural architecture to generalize the sounds of spoken words and adapt to the many ways a single word can sound, and that’s an impressive skill.