2.1 INTRODUCTION
In the last chapter, the differences between contour and
pitch-interval were outlined; it is considered that they might
both be important elements in melody perception, and might both
be represented in some way. However, they are also very different
with contour referring merely to the sequence of ups and downs
but with pitch-interval concerning the amount of change in terms
of absolute interval sizes.
Pitch-interval and contour are clearly different, thus the
investigation of their relative importance poses several problems.
The following chapter discusses some of the problems involved and
presents a detailed methodology of the experiments to be reported.
Apart from Experiments 1 and 2, the methodology for each experiment
is essentially the same; this will be described in detail in the
following sections. Further details of Experiments 1 and 2 will
be found in their appropriate chapters (Chapters 3 & 4).
The last chapter emphasised the importance of presenting
listeners with natural sounding melodies, thus in each of the
experiments reported in the thesis, subjects are asked to listen
to melodies and to direct their attention towards either the pitch-
interval or the contour relationships. However, under natural
circumstances it is likely that both are salient to some degree
and so asking subjects to turn their attention towards the pitch-
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the relationship to the listener.
In each of the experiments subjects perform at least one
pitch-interval and one contour task. In all cases a simple melody
is heard. After a short pause a comparison melody is heard which,
for the pitch-interval task, shares the same pitch-interval values
but possesses one pitch-interval alteration. The task is to detect
this alteration. In a contour task an initial melody is heard in
the same way but subjects are asked to attend to the contour of
this melody. The comparison melody shares only the same contour
(although there are broad similarities, see discussion later); there
is one contour alteration at one point in these comparison melodies
and the task is again to detect this alteration and to press a
button as quickly as possible. The reaction time is, then, a measure
of the salience, or availability, of the pitch-interval or contour
information at any point in a melody.
The reaction times obtained are not discussed in terms of the possible
sub-processes which might be performed by the listener.This is in contrast
to the more general use of reaction time data. For this reason, a detailed
methodology is necessary. In the following pages a general methodology is
given. The issues to be discussed in further detail are underlined.
2.2. General methodology for Experiments 3 to 3
In each experiment subjects, all musicians, were required to
listen to specially composed melodies. These melodies were generated
melodies were recorded on computer files where the frequency and
duration of notes were specified in cycles per second and milli
second respectively. All melody files could be called up into a
more general experiment-controlling program. Separate melody files
were created for each experiment.
Subjects participated in a number of trials in each condition
in each experiment, and the order of the trials was randomised
separately for each subject in each of the conditions. The computer
was set to run through the trials in this order before the experiment
began.
Subjects always practised the task to be performed before each
condition began, using specially-composed practice trials. The pro
cedure for the practice trials was the same as for the experimental
trials. In each experimental trial subjects were asked to listen to
a melody of a specified length. This melody was heard binaurally
through headphones at a loudness of approximately 80dB (the same for
both ears). Subjects were asked to attend to the pitch-interval or
contour of the melody.
After a 5-second pause a second melody was heard (either
transposed or not, depending upon the experiment) which shared either
the same pitch-interval values or the same contour throughout except
that this comparison melody usually possessed one pitch-interval or
contour alteration at one point« the task was to detect this alteration
in the same way and subjects initiated each successive trial using
a foot pedal attached to the computer.
At the end of each block of trials, which usually constituted
one experimental condition, a computer print-out specified:
(a) the number of each trial;
(b) the serial position of the note in which the button was pressed;
(c) the time in milliseconds from the start of that note to the
moment of response.
The experiments were conducted in a laboratory in which there
was little ambient noise. Only the subject and the experimenter were
present in the laboratory.
The above presents a brief overview of the procedure used in