ch 12 1

Sensation & Perception

Ch. 12: Sound Localization

© Takashi Yamauchi (Dept. of Psychology, Texas A&M University)

Main topicsAuditory localization

Perceptual grouping

ch 12 2

• Dan Levitin and his interview (NPR)

• http://www.psych.mcgill.ca/levitin/

ch 12 3

Visual stimuli

• Gestalt laws of organization

ch 12 4

ch 12 5

Law of similarity

Similar things are put together

ch 12 6

ch 12 7

Do you see a spinal motion? This picture is called “Dance.” Do you see why?

ch 12 8

Morandi: cups and boxes

Morandi: Matura morta II

ch 12 9

Perceptual organization

• Grouping in music?

• Demonstration– Structure in music

ch 12 10

• Demonstration

• Listen to music (Beethoven, symphony #5)

• Listen to music (Norah Jones “Don’t know why”)

• Listen to music (Lauryn Hill)

ch 12 11

Sound localization

• Demonstration:– Where does this sound come from?

– YouTube Ventriloquist (America's Got Talent) • http://video.google.com/videoplay?docid=-

4976377170423854180&q=ventriloquist&total=2398&start=0&num=10&so=0&type=search&plindex=4

ch 12 12

ch 12 13

• 3 different coordinates– The horizontal coordinate– The elevation coordinate– The distance coordinate

ch 12 14

Figure 12.2 Measurements of sound localization ability. Red squares indicate the actual sound locations, and the circles are the listeners’ estimates of their location. Longer lines connecting the squares and circles indicates less accurate localization.

ch 12 15

Identifying the sound source in the horizontal coordinate

• Interaural differences

– Interaural time differences• Capture the difference in the time that a sound

reaches the left and right ears

– Interaural level differences• Capture the difference in the level of the sound

intensity (sound pressure level) that a sound reaches the left and right ears

ch 12 16

ch 12 17

Identifying the sound source in the elevation coordinate

• Spectral cues– Capture the way the head and pinnae affect

sound frequencies

ch 12 18

• Depending on the level of elevation, the same sound enters the ears in a different

manner.

ch 12 19

Information about distance• Different sound levels• Frequency

– atmospheric perspective (vision)– The quality of sound (frequency) is modified by the

atmosphere.

• Movement parallax– The nearby sound moves quickly than the far away

sound.

• Direct sound vs. reflected sound– Nearby sound tend to be direct, distant sound tends to

be indirect

ch 12 20

The physiological basis for localization

• Interaural time difference detectors

– E.g., a neuron that responds best when a sound reaches the left ear first and the right ear (vice versa) 1 millisecond later.

ch 12 21

Left Ear Right Ear

The same time

ch 12 22

Left Ear Right Ear

The same time

ch 12 23

Left Ear Right Ear

The same time

ch 12 24

Left Ear Right Ear

The same time

ch 12 25

Left Ear Right Ear

The same time

ch 12 26

Left Ear Right Ear

The same time

ch 12 27

Left Ear Right Ear

Different time

ch 12 28

Left Ear Right Ear

Different time

ch 12 29

Left Ear Right Ear

Different time

ch 12 30

Left Ear Right Ear

Different time

ch 12 31

Left Ear Right Ear

Different time

ch 12 32

Left Ear Right Ear

Different time

ch 12 33

Left Ear Right Ear

Different time

ch 12 34

Left Ear Right Ear

Different time