The Auditory System: Perceptual Aspects of Hearing
In this chapter, you will learn about hearing, which is the perceptual experience that
results from the processing of auditory signals. Various perceptual features are
discussed and you will gain an understanding of how we are able to determine the
location of a sound source—this is an interesting capability of our auditory system
because the sound signal itself provides no cue to its origin.
To begin, you will learn about the absolute threshold for detection of an auditory
stimulus and difference thresholds, as well as the procedures used to determine these
thresholds. The sone scale of loudness will be explained and the intensity–loudness
relationship will be discussed. You will learn the 10 decibel rule, which states that the
perception of loudness is doubled with a 10 decibel increase in sound intensity.
The perception of frequency and pitch is discussed next. Humans can detect sound
frequencies in the range of 20 to 20,000 Hz. Frequencies below this range are called
infrasonic and those above are ultrasonic. Many animals can detect ultrasonic sound
frequencies. Acoustic pitch is discussed and you will learn that there is not an exact
relationship between pitch and frequency. An explanation of pitch coding mechanisms is
then presented and in this context, you will examine the problem of the missing
fundamental. The problem is simply this: we will perceive the fundamental frequency of
a harmonic series when the fundamental frequency is not actually present in the
stimulus. By definition, this is an illusory perception and any theory of pitch perception
must be able to account for this finding.
The final section of the chapter addresses our ability to localize sounds in our
environment. Interaural intensity difference is one important cue that aids in our
localization ability. This cue is based on the fact that the intensity of sound reaching
each ear will differ based on which is ear is closer to the sound source. The other
important cue is interaural time difference which relates to how long it takes sound to
reach each the ear—the further the sound source is from the ear, the longer it takes
sound to reach it compared to the ear closer to the sound source. The neural
underpinnings of sound localization will also be described.
This chapter will help you 2
build on the information learned in chapter five, by relating the physical stimulus
of audition to the perceptual experience. For example, you will understand that
although the physical intensity of a sound can be held constant, our perception of
how loud the sound is may be affected by many factors, both biological and
apply the concepts of psychophysics to audition through examples and
demonstrations. You can experience the experimental methods and findings, as
well as some of the auditory phenomena such as the missing fundamental and
equal loudness contours themselves, by visiting the Auditory Demonstrations
website and participating in the online demonstrations
compare and contrast the different scales that have been developed to quantify
the quality of sound. You should also be able to discuss each scale in terms of
the relationship they describe between an aspect of the sound stimulus and the
connect the physical property of frequency to the perceptual property of pitch and
be able to explain how sounds of different frequencies affect the basilar
membrane. You should also be able to connect previous learning of place and
frequency theory to describe how activation in specific areas of the basilar
membrane by different frequencies is coded such that we are able to make
judgments of pitch.
explain how the human auditory system and brain use auditory signals such as
interaural time difference and interaural intensity difference to localize sounds.
You should also understand that, although humans are fairly accurate in
localizing sounds, background noise, masking, and other factors can affect this
describe and discuss the cocktail party effect in terms of what it tells us about our
ability to ‘fill in’ missing sounds. You are encouraged to visit the Blind Source
website for a demonstration of the cocktail party effect to further their
understanding of the difficulty of the task (demonstration 3 at
Indicate whether the statement is true or false.
____ 1. A disadvantage of the closed-ear method is that individual differences can
result in different pressure being applied to the eardrums.
____ 2. Different frequencies can result in threshold sensitivity differences.
____ 3. The sone scale can be used as a loudness scale for all frequencies.
____ 4. Masking affects our perception of a particular sound in the presence of other
____ 5. An individual who is deaf in one ear is just as good at localizing sounds in the
environment as an individual who is not deaf in either ear.
Identify the choice that best completes the statement or answers the question.
1. Which of Fechner’s methods can be used for obtaining the absolute threshold of
a) Method of Adjustment
b) Method of Limits
c) Method of Constant Stimuli
d) All three can be used
2. Humans are most sensitive