Sound Science Notes
→ Sound is a form of energy which produces sensation of hearing in our ears.
→ Sound needs a medium, such as air, for propagation. As sound travels through air, there occur changes in pressure and density in air. The region in which air is at high pressure and high density is called compression. The region in which air is at low pressure and low density is called rarefaction.
→ Sound travels in the form of waves. A wave consists of cycles of alternate compression and rarefaction. The number of cycles produced in the air (or any other medium) per second is called the frequency of the sound wave. It is expressed in hertz (Hz).
1 hertz = 1 cycle per second or 1 vibration per second or 1 oscillation per second.
→ In musical instruments like sitar and violin, vibrating strings produce sound. In musical instruments like flute and shehnai, vibrating air column produces sound.
→ In the humans, sound is produced in the larynx. Here, production of sound occurs due to vibrations of the stretched vocal cords (= chords in Anatomy), [chord = a variant spelling of cord used in Anatomy]
→ Very loud sounds can be produced by using a loudspeaker. If sound level is around 100 decibels, the sound can be harmful to us.