UNIT 8: LIGHT AND SOUND

UNIT8: LIGHT AND SOUND.

3.-Sound and its characteristics.

3.1.- Sound.

Sound is a form of energy called sound energy. It can produce changes in certain objects.

For example, the sound of an explosion can break windows.

Any vibrating object produces sound. For example our vocal cords vibrate when air passes our throats, creating our voices.

3.2.- Characteristics of sound.

Every object emits a characteristic soun when it vibrates. The different qualities of a sound lets us tell the difference between them:

Intensity: a sound ś intensity can be soft like a whisper or loud like and explosion.

Pitch: A soundś pitch can be high or low. A soundś pitch can be high or low. A soundś pitch will be low if the vibration is produced over a large area. If the area is small, then its pitch is high.

Timbre: it is what lets us differentiate between similar sound, like the difference in timbre of a flute or a saxophone although they are playing the same note.

3.3.- Spreading sound.

The main characteristics are:

• Sound travels in all directions.
• Sound spreads in a straight line.
• Sound is much slower than light. It travels at 340 meters per second.

3.4.- Echo and reverberation

When a sound is emitted and reaches an object, it can reflect or bounce. Depending on the distance of this obstacle, two different phenomena can occur:

• Echo: this happens if the obstacle is more than 17 metres away and there is a clear difference between the reflected and emitted sounds.
• Reverberation: this happens when the obstacle it is as a shorter distance and the reflected soud mixed with the emitted sound.

ACTIVITIES:

1.- Define:

a) sound

b)Intensity

c) pitch

d) timbre

2.- name the main characteristics of spreading sound.

3.- Explain the differences between echo and reverberation.