Beating, beats: Slow beats or low-frequency beats appear as a slow rise
and fall in loudness of the sound owing to a small difference in frequency when two notes vibrate simultaneously.
Cent: A unit which measures interval width. It is based on an equal-temperament
semitone being 100 cents. Any interval can be converted into cents by using the formula (1200/log2)% log i whereas
i represents the intervallic ratio.
Harmonicity, inharmonicity: How closely the spectral frequencies of a sound
correspond to a harmonic series, or how closely the pitches of the pure tone sensations of a sound correspond to
those of a typical complex tone.
Masking: Complete or partial "drowning out" of one sound by another.
Octave stretch: Effect by which octaves in music correspond to frequency
ratios slightly larger than 2:1.
Pitch shift: Slight change in the pitch of a tone due to change in level
or the presence of masker(s).
Pythagorean comma: If one goes around the circle of fifths using the pure
fifth, 3/2, the ending point will be 23.5 cents sharper than the starting pitch. This discrepancy is called Pythagorean
comma.
Wolf fifth: The name given to the undesirable and unpleasant fifth in tuning
and temperament.
*Definitions taken from Richard Parncutt, Harmony: A Psychoacoustical
Approach (New York: Springer-Verlarg, 1989), 167-81.