Pitch

	The perceptual correlate of frequency: the perceptual dimension along which sounds can be ordered from low to high.

The bottom line

	Pitch perception involves the integration of spectral (place) and temporal information across the spectrum.

Scales of pitch

mel scale

Pitch has two qualities

	Pitch height
	Pitch chroma
		Octave equivalence

musical scales

2AFC Frequency Discrimination

Terms for frequency discrimination threshold

	ÆF
	frequency DL, DLF, FDL
	ÆF/F, Weber Fraction
	jnd for frequency

Frequency discrimination

	Does WeberÕs Law apply?
	Do the results of frequency discrimination experiments suggest that people use the place code or the temporal code (phase locking) to figure out what the frequency of a tone is?

Pure-tone frequency discrimination

WeberÕs Law and Frequency Discrimination

Why does it get worse at high frequencies?

Representation of time waveform of a tone

Effects of tone duration

Duration and the place code

Prediction

	Shortening the duration of the tone should have a bigger effect on frequency discrimination if frequency is being coded temporally.

Effects of duration of pure-tone frequency discrimination

These and other findings suggest that a temporal code (phase-locking) is used to code low frequency tones, but that the place code is used to code high frequency tones

	But notice that we do better, relatively speaking, with the temporal code. People use whatever works best.

Well, tones are fine, but..

	Most sounds are complex. How do we perceive the pitch of complex sounds?

The pitch of a harmonic complex

	Pitch is a unitary percept: You hear one complex tone, not 6
	If a listener is asked to match the pitch of the complex to the pitch of a pure tone, they will choose a pure tone at the fundamental frequency.

In fact, if you present the harmonics alone, you still hear the pitch of the fundamental

	Pitch of the missing fundamental
	Virtual pitch
	Residue pitch
	Low pitch

Possible explanations for virtual pitch

	Distortion? No, because masking the frequency of the fundamental doesnÕt affect the pitch.

Possible explanations for virtual pitch

	The system isnÕt just taking the difference between harmonic frequencies, because shifting the harmonics, but keeping the difference the same, changes the pitch.

Two classes of theories of complex pitch

	Template (pattern) theories
		Place code
	Temporal theories
		Temporal code (phase locking)

Template theories

Temporal theories

Resolved v. unresolved harmonics

Resolved v. unresolved harmonics

Template v. temporal theories: Evidence

	Existence region of virtual pitch: Occurs even when all harmonics are unresolved (albeit weaker), but also when all are resolved.
	Dominance region: Resolved harmonics are more important in determining pitch

Evidence that argues that temporal coding must play a role

	Burns & Viemeister (1982): Can listeners identify melodies played with sinusoidally amplitude modulated noise?

Is pitch peripheral?

	Both the place code and the temporal code in the auditory nerve response are used in pitch perception.
	But pitch perception must involve neural, central processes too
		Where are the templates stored and compared?
		How are place and temporal information combined?

Conclusions

	Both spectral (place) and temporal (phase-locking) information appear to be important in pitch perception.
	The situations in which spectral and temporal information are useful in determining pitch differ.
	There is no consensus on the appropriate scale of pitch.

Text sources

	Gelfand, S.A. (1998) Hearing: An introduction to psychological and physiological acoustics. New York: Marcel Dekker.
	Moore, B.C.J. (1997) An introduction to the psychology of hearing. (4th Edition) San Diego: Academic Press.
	Yost, W.A. (1994) Fundamentals of hearing: an introduction. San Diego: Academic Press.