# Determine the minimum distance between the listener and reflector for an echo to be heard distinctively of a sound propagating with a speed v m/sec ? (v=340m/s)

2
by sejaiumardevi

• qais
• Content Quality
2016-02-17T19:23:50+05:30

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As we know that the perception of a sound usually endures in memory for only 0.1 seconds
so, minimum time for echo = 0.1 sec
distance = d
sound have to travel, from listener to reflector then to listener
so total distance travelled = 2d
now, distance = speed
× time = 340 ×0.1
⇒2d = 34
⇒d = 17 m
minimum distance for echo is 17 m
2016-02-17T19:24:48+05:30
Okay lets get our facts straight...

Our ears have a time limit before they can switch between sounds

That is 0.1 seconds....Now the speed of sound in air is about 344

So the Distance covered will Be

But remember an echo has to get reflected so it must travel twice a given distance.

Hence

Now we get that the minimum distance for echo is 17.2 m