In Chapter 10 we discussed methods the auditory system uses to locate and identify sound sources. But for humans, the visual system is the primary channel for perceiving where and what an object is. For our species, the most important function served by hearing is probably communication. Perception of music and speech, the two most common methods of auditory communication, are the topics of this chapter.
A string of musical sounds as short as five notes is plenty long enough to convey a memorable message (you are mostly likely familiar with one such string from the 1977 sci-fi classic Close Encounters of the Third Kind; click here to hear). The first activity for this chapter covers the basic building blocks of musical melodies—Notes, Chords, and Octaves (Activity 11.1).
As important as music is to popular culture, speech is much more central to our species’ identity. In all likelihood, visual systems were already pretty highly evolved by the time our primate ancestors reached the proto-chimpanzee stage. But the evolutionary leap from there to Homo sapiens seems to have driven by the development of brain structures that could process complex symbolic sounds—language (click the image above to hear President Roosevelt speak the morning after the attack on Pearl Harbor).
You will develop a better appreciation of the complexities of language processing in the activities on Categorical Perception (Activity 11.2), The McGurk Effect (Activity 11.3), and how we find Word Breaks (Activity 11.4) in spoken sentences. Finally, an essay on the issues researchers face when Studying Brain Areas for Language Processing (Essay 11.1) helps to make the connection between neuroanatomy and auditory perception.