Echolocation is a process used by some mammals like dolphins to locate objects around them. It works by emitting sound waves and calculating the time delay of echo returns to determine distance and direction. Dolphins use echolocation through single sound transmitters and their two ears. If a dolphin emits a 150,000Hz sonar pulse towards fish 250m away, the echo would return in 0.4 seconds based on calculations using the speed of sound in saltwater.

2. • Echolocation is used by some mammals as a means of
locating themselves in their environment, and
determining what objects are around them.
• In principle, echolocation is the same as active sonar;
where a sound wave is emitted and the distance is
determined by the time delay between the sound
emission and the echoes which return.

3. Source:
http://askabiologist.asu.edu/echolocat
ion
• Unlike sonar-which uses
many beams and multiple
receivers- animal
echolocation has only one
transmitter and 2 receivers
(the ears)
• Animals have two ears
which are spaced apart.
This results in a time
difference and intensity
difference between sound
waves hitting each ear
• The time and loudness
allows the animal to
determine distance and
direction

4. • Echolocation can be conceptualized through the ideas of
the bulk modulus, wave frequency and the speed of a
wave in a media (such as water)
• B =
∆𝑃
∆𝑉
𝑉
; 𝒗 =
𝑩
𝒑
;
𝒗
Λ
= 𝒇

5. • A dolphin is searching for food and emits a sonar pulse
outward toward the open water. It then waits for a return
frequency to determine if there are fish out at sea.
Given:
• Sonar pulses emitted by dolphins have a frequency of
approximately 150,000Hz.
• The bulk modulus of water is 2.0x109
N/𝑚2
.
• Thedensity of saltwater is 1029 kg/𝑚3.

6. a. What is the wavelength of the dolphin’s echolocation
wave?
a. 15.0 mm
b. 7.5mm
c. 9.3mm
d. 10.0mm
b. If the fish is 250 m away from the dolphin, how long
after the sonar pulse is emitted will the echo be
returned?
a. 1 sec
b. 0.5 sec
c. 0.4 sec
d. 0.1 sec

7. A)
First, we start by finding the velocity of the wave:
𝐵
𝑝
= v ;
2.0x109 N/ 𝑚2
1029 kg/ 𝑚3
=1.4 x 103
m/s
Then we need to find the wavelength:
Λ =
𝒗
𝒇
;
1.4 x 103 m/s
1.5x105 Hz
= 9.3 mm

8. B) Knowing the velocity we can solve for the time:
Time = distance / velocity
t = 2(250 m) / 1.4 x 103
m/s
t = 0.4 sec
* We need to double the distance because the wave has to
go forward and get bounced back.