Musical Acoustics Demonstrations
Just Noticeable Difference (jnd) for
Frequency
Background
Pitch is the perceptual correlate of frequency, that is, if a musical
instrument or a computer produces high and low frequencies, the human
ear hears a pitch that is higher or lower. The Just Noticeable
Difference, or jnd, sets a limit on the smallest amount of
frequency change that might be useful musically, either for scale steps
(if you wanted to have many scale steps in an octave), or for fine
tuning adjustments.
A semitone is the smallest standard step size in european music, and
represents about 6% change in frequency. A musical cent is 1/100
of a semitone, or about 0.06% change in frequency.
Instructions
The sound file contains several pairs of notes, near 250 Hz. Each
pair is repeated once. Listen to all the pairs, as many times as
you like, and record whether the second note is higher or lower in
pitch than the first note. The smallest difference that you can
reliably detect would be your jnd for frequency.
Play the sound file
Csound files
pitchjnd.orc
pitchjnd.sco
Supported by Baldwin-Wallace College and the Acoustical Society of
America