From sound to meaning: hearing, speech and language

# 1 Overview

As you walk down the street one day, you hear a voice from somewhere behind you that seems to be discussing this course. It says:

> ‘My dad's tutor's no joker, and he told me the TMA's going to hit home with a bang.’

You turn to find the face behind the voice, which is a gravelly Glaswegian baritone, but the man has gone, leaving you to ponder what he has said. Let us call his sentence example (1). We will come back to it throughout the course.

At the same moment, in Amboseli National Park in Kenya, a group of vervet monkeys (Figure 1) is foraging on the ground near a large baobab tree. A young male on the periphery of the group suddenly stands on his hind legs and gives a loud triple barking sound. The other monkeys have no doubt what this means: a snake is in the vicinity. The monkeys group together, scouring the grass for the location of the predator.

Figure 1 Vervet monkeys (Cercopithecus aethiops)
Figure 1
Copyright © Tony Camacho/Science Photo Library

In both these scenarios, a primate brain performed one of its most remarkable tricks. It took a pattern of vibration off the air and turned it into a very specific set of meanings. How the brain achieves this trick is the subject of this course. The monkey example is interesting because it has been seen as a model of the early stages of human language. Vervet monkeys have several distinct alarm calls – snake, leopard and eagle are the best studied – each one of which can be said very definitely to have a meaning. We know this because on hearing an eagle call played back by a researcher's tape recorder, the monkeys scan the skies, whilst when a leopard call is played, they climb a tree (Seyfarth et al., 1980). Thus quite different associations are being evoked in the vervet brain.

But in this course, the vervet monkey example will mainly be used as an illustration of how different human language is from the communication system of any other primate. The computational task for the human brain in understanding a single sentence is vastly more complex than the vervet case, at every level. It is so complex that a whole field of research – linguistics – is devoted to investigating what goes on, and it requires a whole set of brain machinery that we are only beginning to identify. Hearing and understanding a sentence, or the reverse, where a thought in the brain is turned into a string of buzzes, clicks and notes we call speech, is the crowning achievement of human evolution and the defining feature of human mental life. No other species that we know about comes even close, as the examples below will illustrate.

## Activity 1

Write down the main ways in which you think human language and the call system of the vervet monkey might differ. Keep this list with you and compare it with the differences mentioned in the text as you go through the first half of this course.

This course is in two parts. In the first half (Section 2), we will investigate the nature and structure of human language, keeping our vervet monkey example on hand at all times as a comparison. The aim of this first half is to come to a precise understanding of just what the task is that the brain has to perform in processing language. This paves the way for the second half of the course (Section 3), where we consider different lines of evidence on how and where in the brain this feat is achieved.

OpenLearn - From sound to meaning: hearing, speech and language
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