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why we cannot heard echo in small room?

we can't hear echo in the small room because in it the sound can't be reflected back.

echo is not heard if the distance between the surce of sound and the obstacle is less than 17 m .

sorce: Dinesh Super Simplified Science Class 9th Physics

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no it is not necessary that sound be reflected by 17m 

my store room is empty it is not more than7m but i can hear an echo

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You can hear an echo if there are no objects in that room because if there are objects they absorb the sound

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We can hear an echo when the distance between the medium producing sound be 17.2 m from the wall.

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you know that echo is refecting back of sound . if  the sound presists in our ear for more than 0.1sec than echo is heard . more over temperature also dertermines it . if the temp. is more speed will increase and distance could be reduced of decreased also .

for more details refer to the ncert class 9th or dinesh super simplifiied science physics class 9th.

you may also consut this to your subject teacher or tution teacher .

if you paid meber on merit nation you can consult the study material of class 9th cbse chapter : sound

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 You can hear an echo if there are no objects in that room because if there are objects they absorb the sound  

the thing to kkep in brain tht there shoukd not be any empty walls if u dont wish to hear an echo

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 The first one is right. There are reflections, but they arrive quickly as the distances are small. You notice late reflections as echoes not early reflections.

Insulation has nothing to do with it, acoustic absorption would alter the loudness of the reflections and this would have an effect. A large room can be treated with a lot of acoustic absorption and this too would have few reflections and no perceived echo.


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echo cannot be heard because wood ,which is used in classroom,absorbs sound

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Condition for a echo to be heard is the interval between the sound from source and reflected sound should be 0.1 second and also we can conclude that minimum distance for echo to be heard is 16.6m or approx 17 m by requ. dist. Be x then the sound will travel twice first from source to wall and then wall to source hence s will be 2x=vt
X= vt/2
X= 332m/s *.1s=16.6m
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BECAUSE THE DISTANCE BETWEEN THE SOURCE OF SOUND AND THE REFLECTING MEDIUM IS LESS THAN 17.2M
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The minimum distanse between object shaould be 17m and above
This ans is according to my tutionn tr
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The minimum distance required for the production of echo is 17.2m. The room is small so echo can't be produced in it.
 
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Answer could be taken out from this paragraph

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We cannot hear an echo in a small room as we cannot distinguish two sounds when the duration between them is less than 1\10 secs. 
Therefore mathematically,
speed of sound=340m\sec
let the minimum distance of hearing an echo be y
340\2 X 1\10 =340/20 IS EQUAL TO VELOCITY X Y/2
THEREFORE THE MINIMUM DISTANCE=17M
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Because, in small room the length of room having more than 17m then we hear eco in small room
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gfffh
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As others have mentioned all rooms (with the exception of anechoic chambers) will have some reflections of the sound waves. The material of the walls and shape of the room will have a major effect on the type of reflections you get.

There are several ways we perceive sounds in a room which our auditory system integrates into a whole experience of the sound.

1) Direct sound - This is the sound arriving direct to your ears with no reflections
2) Early reflections - The first direct reflections from the room. This helps us to localize the sound for frequencies over about 1kHz. We typically don't perceive this as a different sound to the direct sound because the time interval is too short (up to about 30ms) 
3) Reverberation - This is kind of a wash of reflections bouncing all over the room. 
4) Echo - If the size of the room is large (or the reflective wall far away) the reflections will be far enough apart that we can perceive them as seperate events and a true echo (over about 80-100ms is probably enough time)
In a small room all reflection events happen so quickly due to the small space that the early reflections/reverb stages are kind of rolled into one and the size of the space is too small for an echo.

The reverb time (measure of how quickly the reverberant sound drops 60dB) is a lot less for small rooms because more reflections happen in a short space of time and the sound waves get absorbed quickly.
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We can not hear echoes in small room because the sound waves reflect back in friction of second so it is no eligible to hear the echoes in small rooms.
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Sound does echo inside a room but you might not notice it much for two reasons.

Firstly the time for the echo to return is very small so you will not hear a long sound repeated as an echo, instead you will get a resonance type echo, like when you sing in the bathroom.

Secondly most rooms are full of soft furnishings that quickly absorb the sound and damp the resonance.

If you are in a large room with no furnishings and you clap once loudly you will certainly hear the echo rebounding rapidly off the walls.

IF HELPED PLZ . THUMBS UP
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we cannot hear echo in a small room because the length of the room is less than 17.2 m
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Because the is the room is lesser.and echo required a distance of 344m/s?0.1s=34.4m
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Because the distance in the room between the reflecting surface and the speaker is less and echo required a distance 344m/s ?0.1s=34.4m.
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It happens because echo needs a minimum distance of 17.2m from the speaker to the hard substance or cliff,etc.
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We can hear an echo when the distance between the medium producing sound be 17.2m from the wall
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sound cant be reflected back
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*What is Echo?
Ans) Echo is defined as one time of reflection of sound from a cliff or building or sound reflecting surface i.e. Mountains.
The factors which is essential for the production of echo is what is minimum length required so that echo can be produced is 17.2m.
So if echo production had to take place then the difference between source of sound i.e. a boy and a sound reflecting surface i.e. walls/mountains /room is 17.2m ....
If distance is less than 17.2m then echo will not be produced
Plzzzzzz cheeerz upp
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We can't hear echo in small room because it at the sound can't be reflected back echo is not heard if the distance between the source of sound and obstacle is less than 17 m
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why experts are not answering??.

 
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We cannot hear echo in small room because the sound bounces back from the wall of the small room. Echo can be defined as asound heard by an observer after it reflects from a rigid surface
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We can't hear echo in a small room because the distance of the medium is short and for occuring echo longer distance is required . For eg. if we go an shout in the mountain the sound will be hear as echo because there is long distance
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Because there is no any medium to travel sound that's why we can't hear echo
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You can hear echos in small room.? You probably just don't interpret them as such.? You probably perceive it as normal.
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To heard eco the minimum distance should be 17m
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For echo the distance of reflecting surface from the source should be more than 17.2 metre so in a small room it is and it is impossible to hear an echo
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What comes after 0.1 sec is a reverbration ,not an echo........In aclosed room reverbration takes place because it reaches within 0.1 sec.....
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for echo minimum length is required from wall is 17 metre
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We cannot hear echo in a small room as the object producing sound should be 17 m away from the reflecting obstacle
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Because it attracts the wall very fast and loose its energy while in big room it does not attracts fast
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we can't hear echo in the small room because in it the sound can't be reflected back.

echo is not heard if the distance between the surce of sound and the obstacle is less than 17 m .

sorce: Dinesh Super Simplified Science Class 9th Physics
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To hear an echo , our distance from the reflecting surface should be at least 17.2m which is not possible in a small room.

Hope it will help you...
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Minimum distance for echo to hear is 17.2 m and in a small room distance it kindof small so there is no echo produced
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minimum distance for eco to occur is 1.75 metre
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That is because the minimum difference between the sound and the reflector should be 17m.
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Echo:-The phenomenon of reflection of sound from a surface is called?echo.?They can't hear?an?echo in small room?because in it the sound?can't?be reflected back. For an?echo?of a sound to be heard,the minimum distance between the source of sound and the walls of the?room?should be 17.2 m.
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because of sound absorbed object
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Beacause.their is no enogh space for repetation of soubd for echo
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Because it travels (sound) very fast and have a faster reflection In a small room compared to a large area #21
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We can't hear an echo in a small room because the distance between the observer and the reflector of sound is less than 17m. And according to the conditions required for hearing an echo, maximum distance between the source of sound and the reflector must be 17m.
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They?can't hear?an?echo?in?small room?because in it the sound?can't?be reflected back. For an?echo?of a sound to be?heard,the minimum distance between the source of sound and the walls of the?room?should be 17.2 m. Obviously,in a?small room echoes cannot?be?heard.
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