Barn Owl

Question 1

Barn owl - genus species

Answer 1

Tyro alba

Question 2

Features of barn owl sound localization

Answer 2

with extreme accuracy in both azimuth and elevation without moving its head (Knudsen et al., 1979)

Question 3

What must the barn owl do to localize sound?

Answer 3

To identify the location of a sound source in two dimensions, the owl’s auditory system must make independent measurements on at least two different, space-variant parameters of the auditory stimulus.

Question 4

What are cues for sound localization derived from?

Answer 4

are derived from a binaural comparison of a sound’s arrival time, phase, intensity and spectrum

Question 5

Interaural arrival time (AT) refers to

Answer 5

delay in the onset of a sound at the two ears

Question 6

interaural phase (AP) is the

Answer 6

relative phase shift in the ongoing waveforms at the two ears.

Question 7

Both AT and AP depend on

Answer 7

the difference in the path lengths that sound must travel to reach each ear, and therefore vary as a function of the azimuth of the sound source

Question 8

Interaural intensity (AI) refers to

Answer 8

the difference in the amount of sound energy reaching each ear

Question 9

interaural spectrum (AS) is

Answer 9

the difference in the distribution of sound energy as a function of frequency (power spectrum) in each ear

Question 10

Direction dependent AI and AS cues are caused by

Answer 10

changes in the sensitivity of each ear as a function of sound direction (ear directionality)

Question 11

Who conducted an experiment to work out how barn owl’s localize sound?

Answer 11

Knudsen and Konishi (1979) measured the accuracy at which the Barn owl could orient its head to a sound source normally, during occlusion of the either ear and removal of the ruff feathers.

Question 12

What did occlusion of the right and left ear do?

Answer 12

Occluding the right ear caused the owl to orient below and to the left of the sound source; occluding the left ear caused it to orient above and to the right of the sound source.

Question 13

What did removal of ruff feathers do?

Answer 13

With ruff feathers (facial ruff) removed, the owl continued to localize sounds accurately in azimuth, but failed to localize sounds in elevation.

Question 14

What did Knudsen and Konishi’s results show?

Answer 14

demonstrated that barn owl uses interaural comparisons of sound spectrum to determine the elevation of a sound source. Both interaural onset time and interaural spectrum are used to identify the azimuth of the sound source. If onset time is not available (as in a continuous sound), the owl can derive the azimuth of the source from interaural spectrum alone, but its spatial resolution is poorer.