Pitch perception Basilar membrane unrolled

8/12/11

Pitch perception Basilar membrane unrolled

•  Cochlear frequency tuning
•  Place vs. temporal/volley code
•  Cochlear implants
•  Virtual pitch

Traveling wave Traveling wave

Frequency tuning Frequency tuning in the cochlea

Distance (mm) 30 Z wisloc ki
pos t- m ort em s

20
10 distance ~ log(frequency)

10,000 1000 100

Frequency (hz)

1

8/12/11

Frequency coding by place on the cochlea Response to a tone complex

Courtesy James Hudspeth

Frequency tuning in the cochlea Frequency tuning of the auditory nerve

Characteristic frequency

2

8/12/11

Volley principle

Phase locking Electrical stimulation experiment

(John White)Pitch (inches)
Stimulating electrodes

Frequency (Hz)

Fundamental frequency and harmonics Flute (open pipe) harmonics

3

8/12/11

Flute (open pipe) harmonics Virtual pitch

Other notes (shorten the pipe) Demo:

Reinforcing a harmonic (forcing a node )

Shepard pitch illusion

Demo:

SPL

f 2f 3f 4f 5f 6f
Frequency

4