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vocal musIc reproductIon
that they were invariably played on CD or radio
stations at the same tempo. The subjects recalled
and reproduced these tempos very well: 72% of
the participants sang within 8% of the expected
tempo for a given song. In a second experiment,
volunteers hummed well-known folk tunes, which
by their nature do not have a single performance
tempo associated with them. The results showed
that subjects' chosen tempos showed some con-
sistency, but not to the same degree as was seen
in the first experiment; tempo values typically
varied between 10 - 20%. The authors note that
this second result confirms observations made
in the earlier study by Halpern (1988) on tempo.
Further analysis of the results from their 1994
experiment showed that there was no correlation
between subjects who scored well in estimating
tempo and those who reproduced accurately the
initial pitch of a song.
Lindsay's MS thesis work (1996) included a
small study in which 6 subjects listened to a series
of 32 five-note sequences, vocally reproducing
each one after hearing it. These short phrases were
carefully designed to test all 16 possible binary
pitch contours as well as all pitch interval sizes
between 1 and 7 steps. He measured how well the
subjects were able to reproduce each phrase, and
he proposed and tested several representations of
the user input to see how well each matched the
user input to the associated stimulus phrase. Based
upon his experimental results, Lindsay proposed
a straightforward representation of user input for
which a musical phrase of
n
notes is represented
directly by the
n - 1
pitch interval values sepa-
rating consecutive notes. (The intervals would
be measured in cents, a more precise measure
of pitch to describe notes which fall between
two consecutive semitones in the Western tonal
scale. The pitch space between any two adjacent
semitones is divided into 100 cents.)
McNab et al. (1996) conducted a short study
as part of their efforts to build an MIR system.
Ten subjects sang or hummed ten familiar songs,
which were measured to see how well the subjects
A more limited number of studies have been
conducted which explored aspects of human
humming or singing.
Halpern (1989) studied the ability of subjects to
reproduce consistently the starting note of familiar
songs, given only a song's title and its first line
of lyrics. The songs chosen for the study were
popular traditional or folk tunes which tend to be
performed in varying keys, reducing the likeli-
hood that subjects formed mental models of songs'
performance keys solely through hearing them.
Her results showed that subjects, both musical and
nonmusical, made consistently similar choices
for their starting pitches among different trials
for the same song, and that the choices differed
for different songs.
A complementary study was performed by
Levitin (1994). His work tested subjects' ability
to reproduce the starting notes of modern popu-
lar songs selected by the subjects. In contrast to
Halpern's data set, the songs in this study were
chosen because they are generally only heard in
one key as recorded by the musical artist. In the
experiment, subjects were shown a selection of
58 CDs and were asked to select two songs from
among them. They were then to sing or hum a
few notes from any point within the songs chosen.
The result was that 40% of the subjects used the
same pitch as the recorded song on at least one
trial, and 12% matched the pitch for both trials.
In addition, 81% were within 2 semitones of the
pitch for at least 1 trial, and 44% were within 2
semitones for both trials. These results clearly
are not due to chance and show that ordinary
subjects have some memory skills for reproduc-
ing musical pitches.
Another study by Levitin and Cook (1996)
explored subjects' ability to reproduce the tempo
of familiar songs. The first experiment of this
study utilized the data collected from Levitin's
1994 study, described above, which was performed
using a set of popular songs with the characteristic
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