SOUND EXPERIMENTS

SOUND EXPERIMENTS

How can we hear it?

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WHAT IS A SOUNd?

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WHAT ARE ITS PROPERTIES?

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(if you want to discover the answers, click on the grey icons)

To better understand what is a sound we can start with a simple experiment. Clap your hand on the table. In this way you can hear the sound produced and perceive the vibrations. You can notice that harder you clap on the table, louder is the sound, so the amplitude increase.

voice's experiments

WHAT IS VOICE?

ALL OF US CAN BECOME SINGERS! To do this we can create a relaxing and funny experiment: just taking a shower. When we sing in the shower the sound played is much better than in other spaces. That's why a shower is usually a tight space, so the voice acquires a deeper timbre and improves the bass tones, then gets power. So when we sing in a shower we sound better, because the sound waves fit perfectly within that shower.

BROKEN CRYSTAL GLASS:A glass, as our voice, can product sound waves. It's very difficult, but sometimes a very good singer is able to play a sound with his voice, which contains the same frequency, as that of the glass. In this way a wine glass could be broken because of a human voice.

We can answer to this question doing a simple experiments: While we are talking, if we touch our neck, we can feel a vibration, but if we stop talking we don't feel it anymore. That's why our voice is a sound produced by oscillations.

WHAT ABOUT SOUNDS UNDER THE WATER?

Here we can see a very interesting video about this topic.Some musicians try to play different instruments under the water because they want to discover new sounds, wich in air couldn't play. (click on youtube icon down here to see the video)

We can hear sounds under the water too, but in a different way. We can prove it with an experiment: we pour some water into a container, then we immerse our ear into it and an other person claps his hand on the bottom of it. Sound is heard, but it is distorted and it's difficult understand where it's from. All of this because water is denser than air and sound propagates much faster.

A JUVENILLE EXPERIMENT

GLASS EXPERIMENT

On the last slide we have also seen that human voice can break a glass, but it's not the only one's able to do this. In this video we will see how a sound can break it too. (click youtube icon to your right to see the video).

In this experiment you are going to prove your age .Only people under 25 years old can hear this sound. That's why our hearing gets older too! When a frequency is too high, usually just teenagers can hear it.

This is possible because the sound, as our voice, has reached the same frequency as the glass.

SOUND EXERCISES

1) In one of the experiments we saw that the sound can't only travel in air, but in the water too, for example when you play an instrument. QUESTION: So, what if someone played under the water a note with a frequency of 450 Hz and it moved at the speed of 1300 m/s. What's its wavelenght? ANSWER: You have to substract speed with frequency (1300/450) and the result is 2.8 m. 2) You can hear a sound making food, for example scrabled eggs. You have to mix eggs, beating a fork on a plate. In this moment you will hear a sound. QUESTION: If I move a fork at a speed of 5 m/s with a wavelenght of 0.3m, what is the frequency? ANSWER: You have to substract speed with wavelenght(5/0.3) and the result is 16.6Hz.