8th Class Science Sound Characteristic of Sound

     Characteristics of Sound

A sound normally has three characteristics, which helps us to recognize the sound. These three characteristics are:

(i) Loudness

(ii) Pitch

(iii) Quality

Two different sounds differs in at least one of the three given characteristics.

           Loudness

Sound is produced by the vibration of objects. If more energy is supplied to the object it will vibrate with larger amplitude, and the loudness of the sound will be more. Thus, the loudness of the sound depends on the amplitude of the vibration. If the amplitude of the sound is doubled, the loudness of the sound will be four times, and if the amplitude of the vibration is halved, the loudness of the sound will be one-fourth of the original sound. The loudness of the sound is measured in decibels. It is denoted by dB. The loudness of the normal conversation is 60 dB and that of the normal breathing is 60 dB. If the loudness of the sound is more than 80 dB then it is called sound pollution or painful sound. The loudness of the jet aero plane is 130 dB.

           Pitch

The pitch of the sound helps us to differentiate between the sounds of same loudness. For example, the sound of men and women of same loudness can easily be differentiated. The pitch of the sound depends on the frequency of the sound. A sound having high frequency is called shrill. The sound of women is shriller than men.

           Quality

Quality is that characteristic of sound, which helps us to differentiate between the sounds of different instruments. The sound produced by sitar, tabia, flute, etc. are different from each other, even if their pitch and frequency are same. This difference in the quality of different sound is because of the shape of the waves, which is different in different instruments.

       The sound produced by the different instruments are different. There are different characteristic of sound, which help us to different between the different sounds. The characteristic of sound which helps us to differentiate between the sounds of different instruments is called:

(a) Pitch

(b) Loudness

(c) Quality

(d) Tone

(e) None of these

Answer: (c)

Explanation

We can easily differentiate between the sounds of different instrument because of its quality.

      The sound is measured in decibels. It is also called the unit of intensity of sound. The loudness of normal conversation of human is:

(a) 10 dB

(b) 30 dB

(c) 60 dB

(d) 80 dB

(e) None of these

Answer: (c)

Explanation

The loudness of normal conversation of human is 60 dB.