Sound by 2E1 Ng Xinying

In this topic I've learnt about what causes sound, the transmisson of sound,more things about the human
ears, the pitch and music and the importance of soun in the society.
Now im going to summarise what i have learnt about the topic.
I have learnt that....
Sound is a form of energy.
Sounds are produced by the vibration of objects.
Frenquency is the number of vibrations per sec. And they are measured in Hertz(Hz)
Sound travels through matter -Liquid,Solid and Gas.
Sound takes time to travel from one place to another. the speed of sound in the air is about 330 metres per second.
Sound travels in form of waves.
The human ear can hear only a limited range of sound frequencies.
The ear is a sound detector that has 3 main parts, the outer ear,the inner ear and the middle ear.
Sound is important in society for communication as a warning and as a pleasure.
Noise is sound that is loud and unpleasant.
the loudness of sound is measured as decibels(dB).
Sound above 90dB can cause damage to our ears.
Ear protectors and noise barriers are two ways of reducing loud noise.
Sound frequencies higher than those that can be detected by humans are called ultrasound.
Ultrasound has many application in industry and medicine.
the higness and lowness of a musical note is called its pitch.
a note with a low pitch is called a low frenquency. A note with a high pitch is called a high frequency.
For wind instruments,the shorter the column of air, the higher the pitch of a note.
For string instruments,the shorter the string the higher pitch of a note.
The vocal cords in our throats produce sounds.
Here's a fact!
Have you experienced a ringing sound in your ears after listening to loud music or noise? People who are continually exposed to loud sounds develop a permanent ringing sound. this affliction ehich cannot be cured is called tinitus.