Let's learn the Behavior of Sound #1

    Hi guys, today I brought you information about the behavior of sound. I hope to divide this lesson to two parts. 

Source

Check my post about The Behavior of light here

Click here to my latest educational post about micro-organisms

• Sound is produced by vibtrating membranes, strings and air columns.
• A medium is necessary for sound to travel.

Reflection of sound

Have you ever experienced when you talk, your own voice can be heard again. Have you observed why it is? Let's see why this happens.

Let's find why by doing this little activity. 

You'll need ;

•  a watch
• two PVC tubes
• a glass sheet
• a piece of cardboard

place them as shown. 

You can hear the 'tick' sound through the PVC tube. This happens due to the reflection of sound by the glass sheet. 

So why do we need a cardboard?

That is to prevent the 'tick' side of the watch reaching your ear directly. Otherwise, the reflected 'tick' sound can't be observed clearly.

Now you may have gotten an idea that sound reflects by obstacles. 

Some phenomena related to reflection of sound

Echo

You may have experienced when you talk in a hall, you may hear back your voice after a while. The reason is reflectng the sound by the walls of the hall.

Source

But we don't hear echo everytime we talk. Why is it???

Sound travels through air at a speed of 330ms-1. The sensetation sound remains in our minds for about 1/10s. So when the sound wave reach the obstacle at a 

speed of 330ms-1 and reflects back to us a time of 1/10s has to be gone. otherwise we won't recognise the reflected sound.

So now you may have got the idea. Let's furher discuss it.

When we are in a small room the obstacle is close to us. The sound source is you. So when you make a sound, the wave reach the wall so fast and reflect back to us. When this happens, if the time 1/10s hasn't spent, we won't recognise the echo because the original sound which we made is in the sensetation of the ear for 1/10s. 

So there should be a minimum distance between you and the obstacle for you to hear the echo. Let's find the minimum distance needed from this calculation.

The distance that sound travels through air in 1 s                                   = 330 m 

Minimum distance that sound should travel through air to hear echo= 330 m s-1 X 1/10 s 

                                                                                                                            = 33 m 

The minimum distance between the observer and the obstacle            = 33 m/ 2 

                                                                                                                            = 16.5 m

 So there should be at least a distance of 16.5m to hear an echo and the sound should be strong enough to be heard by the observer.

All these information is from my science text book

Hope you learned something.

Thank you for stopping by

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