Sound Plays An Important Role in Our Daily Life

Sound
Topics to be covered
 Sound production
 How do humans produce &hear sound
 Characteristics of sound
 Audible and inaudible sounds
 Noise Pollution & Music


Sound plays an important role in our daily life.
It helps us to communicate with one another and express yourself.
Sound is produced by vibrating the objects and it is carried in all directions with the help of a medium.
Sound needs a medium to travel.
It cannot travel in a vacuum.
We hear sound through our ears.
Hearing:- The eardrums of our ears sense the vibrations produced by a vibrating object and send them to the brain
as the stimulus. This process is called a hearing.
Eardrum: A thin membrane which is stretched tightly to receive the waves bf sound at the end of ear canal.
Hertz: The frequency is expressed in hertz (Hz).
Larynx: In humans, the sound is produced by the larynx.
The loudness of Sound: Larger the amplitude of vibration, louder is the sound.
Noise: Unpleasant sounds are called noise.
Oscillation motion: The to and fro motion of an object is called oscillation motion.
Pitch of the Sound: Higher the frequency of vibration, the higher is the pitch, or shrill of the sound.
Shrillness: The frequency determines the shrillness or pitch of a sound. If the frequency of vibration is higher we can
say that sound is shrill.
Time Period: The time taken by a pendulum to complete one oscillation is called the time period.
Vibration: The to and fro or back and forth motion of an object is termed as vibration.
How do humans produce sound?
 The sound produced in the voice box called larynx located at the upper end of the windpipe.
 2 vocal cords get stretched across in the voice box. Has a slit, through which air is forced out by the lungs.
 Muscles attached to vocal cords make it tight or loose.
Human ear
 Outer ear = pinna: collects sound from the surroundings.

 Sound passes through a tube called an auditory canal.
 Eardrum (tympanic membrane) → vibrates when the sound incident.
 Vibrations are sent to the inner ear, from there it goes to the brain as signals via the auditory nerve.
Amplitude, Time Period and Frequency
, and of vibrations
Amplitude:-The magnitude of disturbance in the medium on either side of the mean value is called as Amplitude(A). Larger the
amplitude, louder the sound.
Frequency:- The number of oscillations per second is called frequency. Expressed in Hertz (Hz).
Time period:- Time taken for one complete oscillation to travel across a point. T = 1/f. (Seconds)
Loudness and Pitch

 Volume or loudness of a sound depends on the amplitude. The force with which an object is made to vibrate gives the
loudness.
 The number of oscillations per unit time. Directly proportional to frequency.
Audible and inaudible sounds
Audible Frequencies: For human ears, the range of audible frequencies is roughly from 20 to 20,000 Hz.
 Audible range = 20Hz to 20kHz known as the Sonic range.

 Below 20 Hz (inaudible) → infrasonic range
 Above 20 kHz (inaudible) → Ultrasonic range
Noise Pollution & Music

Noise Pollution: The presence of excessive or unwanted sound in the atmosphere is called noise pollution.
Unpleasant sounds are called as noise.
Major causes of noise pollution are sounds of vehicles, explosions including the bursting of crackers, machines,
loudspeakers etc.
Presence of excessive noise in the surroundings may cause many health-related problems e.g., lack of sleep,
hypertension and anxiety etc.
Plantation on the roadside and elsewhere is the best source to reduce the noise pollution.
The loudness is expressed in a unit called decibel (dB). It also depends on the amplitude of the sound.
Music:-
– Sounds with the same pitch and loudness can be distinguished based on the quality.
Music is pleasant to the ears while noise is not.

Noise pollution and measures to control it

– Presence of excessive unwanted noise in our surroundings is called as noise pollution.
– Can cause hearing impairment, sleeplessness and also hypertension.
– Must be minimised by reducing noisy operations and honking in residential areas. Planting trees along roads also cut down the
noise.

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Sound

 Noise Pollution & Music

It helps us to communicate with one another and express yourself.

Sound needs a medium to travel.

It cannot travel in a vacuum.

We hear sound through our ears.

Hertz: The frequency is expressed in hertz (Hz).

Larynx: In humans, the sound is produced by the larynx.

Noise: Unpleasant sounds are called noise.

 Outer ear = pinna: collects sound from the surroundings.

Amplitude, Time Period and Frequency

Loudness and Pitch

Audible and inaudible sounds

 Audible range = 20Hz to 20kHz known as the Sonic range.

Noise Pollution & Music

Unpleasant sounds are called as noise.

Noise pollution and measures to control it

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