When you are in school, you come to know when the period gets over. When someone rings the doorbell at your door you can hear the sound. Suppose if someone approaching you, you can make it out by hearing the footsteps itself. Sound plays an important role in our daily lives. You hear many types of sound in our surroundings. How is the sound audible to you? Let us discuss these characteristics of sound in detail.
Characteristics of Sound
The sound that we hear around us is the type of energy made by the vibration that travels through the air or any other medium and can be heard when it reaches a person’s ear. So, basically sound helps us to communicate with the other person. For example, we can hear the musical instruments like tabla, flute, a guitar due to vibration. The characteristics of sound are as follows:
Vibrating Parts of Musical Instruments
- Veena – Stretched string
- Tabla – Stretched membrane
- Drum – Stretched membrane
- Shehnai – Air Column
- Flute – Air Column
Pitch is a characteristic of sound by which a correct note can be distinguished from a grave or a flat note. We can identify a female and male voice without seeing them. The term ‘pitch’ is often used in music. Pitch depends upon the frequencies of the sound wave. A note has a higher pitch when the frequency is high and a note of low frequency has a low pitch. For example, when a small baby speaks something, his/her voice has a higher frequency so in case of a baby the pitch is higher than the pitch of a man. The sound with a high frequency is called as shrill.
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The loudness is a sensation of how strong a sound wave is at a place. It is always a relative term and is a dimensionless quantity. Loudness is measured in decibel (dB). It is given as:
L = log(I), here ‘I’ is the intensity.
The loudness depends on the amplitude of the vibration. It will be louder when the amplitude is high. Suppose when we pluck a string of the sitar it starts vibrating with low amplitude and if we apply more energy by plucking more strongly, the string will vibrate with the greater amplitude and produce a loud sound. As the amplitude of vibration increases, sound also increases.
The word timbre also describes the term quality. As different sources produce different sounds, the timbre helps us to distinguish between them. A sound of good quality is pleasant to listen. The instruments are of different shapes and size and they produce different harmonics of loudness hence their sound can be easily distinguished.
Questions For You
Q. At what frequency we can’t the sound of vibrations of a pendulum?
- Less than 20Hz
- More than 20Hz
- 20 Hz
- None of them
Answer: A. The frequency of the vibrating pendulum is small and less than 20Hz which is not in an audible range. Hence it is not heard.