our teacher told that if we want to hear the echo the distance between the wall and person should - Science - Sound

Question

our teacher told that if we want to hear the echo the distance
between the wall and person should be atleast 16 5 m
But in a small empty room we do hear the echo even though the
wall is at a distance less than 16 5 m
so who is it possible

Shukla Paladhi · Accepted Answer

Hi,
The minimum distance to hear echo is found to be 16 5 m when
we consider the speed of sound in air to be 330 m/s
The minimum time interval between the original sound and the
reflected sound must be 0 1s,
Then the distance travelled by sound from the point of
generation to the reflecting surface and comes back = (330 m/s)
× 0 1s = 33 m
Thus, the minimum distance of the obstacle from the source of
sound must be = 33/2 = 16 5 m
In empty rooms we hear echo because of multiple reflection of
sound in the walls In presence of furniture and carpets and other
things in the house the entire sound energy is dissipated and we
don’t hear echo
Hope, this helps you
Best wishes!!

our teacher told that if we want to hear the echo the distance between the wall and person should be atleast 16.5 m . But in a small empty room we do hear the echo even though the wall is at a distance less than 16.5 m. so who is it possible

our teacher told that if we want to hear the echo the distance between the wall and person should be atleast 16.5 m .

But in a small empty room we do hear the echo even though the wall is at a distance less than 16.5 m.

so who is it possible