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Harbor seals, like many animals, determine the direction from which a sound is coming by sensing the difference in arrival times at their tw
Question
Harbor seals, like many animals, determine the direction from which a sound is coming by sensing the difference in arrival times at their two ears. A small difference in arrival times means that the object is in front of the seal; a larger difference means it is to the left or right. There is a minimum time difference that a seal can sense, and this leads to a limitation on a seal’s direction sense. Seals can distinguish between two sounds that come from directions 3∘ apart in air, but this increases to 9∘ in water.Explain why you would expect a seal’s directional discrimination to be worse in water than in air.
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2021-08-21T17:24:48+00:00
2021-08-21T17:24:48+00:00 1 Answers
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Answer:
that the angle must be increased to maintain the minimum time of discrimination due to the increase in the speed of sound in material
Explanation:
The direction of sound is detected by the difference in time of reception of each ear, the speed of the wave is
v = d / t
t = d / v
In air the velocity is v = 330 m / s, let’s use trigonometry
Cos 3 = d / L
L = d / cos 3
The difference in distance is
Δd = d – d / cos 3 = d (1- 1 / cos3)
t = Δd / 330
When the animal is in the water the speed of sound is
v = 1540 m / s
So time is
t’ = Δd ’/ 1540
t ’= Dd’ / 4.67 330
So if t = t’ is the minimum response time, the distance must be increased
Δd ’= 4.6 Δd
1-1 / cos θ = 4.6 (1- 1 / cos 3) = -4.6 0.00137 = -0.00631
1 + 0.0063 = 1 / cos θ
1.00631 = 1 / cos θ
Cos θ = 1 / 1.00631
Tea = 6.5
We see that the angle must be increased to maintain the minimum time of discrimination due to the increase in the speed of sound in material