Characteristics of Sound

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What is Sound?

• Sound is a form of energy that is created by a vibrating object.
• In other words Sound is a form of energy. Each particle transmits its energy to its adjacent particles.
• Most important Characteristic of Sound is that Sound is a Longitudinal wave and it cannot travel through Vacuum. For the propagation of sound, it must need an elastic medium.

What are the characteristics of sound waves?

There are 4 major Characteristics of Sound these includes_
1. Loudness
2. Intensity
3. Pitch
4. Quality

♦ With the help of this characteristic we can distinguish two distinct sounds differently.
Let’s discuss all the major Characteristics of a Sound Wave one by one _


Loudness is an auditory sensation, in which our ear can precept a sound.
• It is a subjective Quantity.

• The loudness or softness of a sound depends on the  Amplitude of that sound wave.

• The  Loudness is directly proportional to the square of the Amplitude of the sound wave.

• The Loudness of a sound wave is Inversely proportional to the square of the distance between the source.

• Loudness also depends on the density of the medium, More density means more loudness.

• Also, it depends on the Surface area of the vibrating body, more surface area produced more loudness.

What is Amplitude?
• The magnitude of a wave is defined by the maximum disturbance of a wave in the medium on either side of the mean position.

• It is usually represented by the letter A.

• Compared to the soft sound a Louder sound can travel a larger distance because a louder sound has higher energy.

Characteristics of Sound - Amplitude
Amplitude is a distinct feature of sound

Unit of Loudness
• Phon
• Sone
• Decibel (dB)

• The unit Phon is used to indicate an individual’s perception of loudness.

• By definition, 1 phon is equivalent to 1 decibels at 1000 Hz (1 kHz).
1 Sone sound is defined as a sound whose loudness is equal to 40 phons

• Loudness of Sound greater than 120 dB, is considered Noise.
• Loudness is a subjective quantity, as because it varies from person to person.

Loudness is a subjective quantity, as it depends on the sensation of hearing of a person.  To solve this problem instead of calculating the loudness of the sound we calculate the Intensity of the sound.


• The amount of sound energy passing per unit time through a unit area is called the Intensity of sound. The area is perpendicular to the direction in which the sound waves are propagating.

• The SI unit of intensitywatt / m2.

• It is an objective quantity. Because we can define it with some numerical value.  Suppose the intensity of a sound is 5 watt m2. Here the value is the same for every person.

➧ In Physics the intensity of the zero decibel sound is considered the weakest intensity which is 10-12 Watt / m2. [10-12 joules of energy passed through a unit area]

Characteristics of Sound - Intensity
Characteristics of Sound – Intensity

Difference between Intensity and Loudness

It is a Subjective quantityIt is an Objective quantity
It is related to the Amplitude of SoundIt is related to the energy passing through unit area
It is the degree of sensation of sound produced in the ear, That means it depends on the sensitivity of war.It does not depend on the sensitivity of the ear.
A Unit of Loudness is Decible (dB)Unit of Intensity is Watt / m2

➧ Objective Vs Subjective Quantity

☛ Objective quantity is identical for every person because it has a definite value and can be expressed with a unit.

☛ An example of objective Quantity is Decibel (dB) and intensity of sound because both the term can be measured or represented with some numerical value, for example, 100 dB and 5 watt / m2 respectively.

Subjective Quantity depends on a person, any sound can be loud for one person but not for another person.

☛ An example of Subjective Quantity is Loudness. It depends on the sensation of the human ear, for example, suppose the loudness of a sound is 100 dB. Here the value 100 is the same for every person, but the sound can be loud for one person but not for other people.


☛ It’s a characteristic of sound by which we can distinguish the two sounds of the same Loudness and instrument but of different frequencies.
☛ In other words, how the brain interprets the frequency of an emitted sound or the sensation of a frequency is called its pitch.
☛ Like Loudness, Pitch is also a subjective quantity.

☛  The Frequency of a sound wave is measured by the number of waves produced per unit of time.
☛ A high pitch sound corresponds to a high-frequency sound wave.
☛ Similarly, a low pitch sound corresponds to a low-frequency sound wave.
☛ The SI unit of Frequency is Cycle per  Second or  Hertz (Hz). 1 Hz is equal to 1 cycle per Second.

Characteristics of Sound - Pitch
Features of Sound – Pitch

Quality or timber

☛  It is a characteristic of the Sound wave by which we can differentiate two sounds having the Same Pitch and Loudness.
☛ The Quality of timber depends on the Waveform of the sound wave.
☛ The sound which is more pleasant is said to be of rich quality. 

☛  A Single frequency (single cycle) sound is called a Tone.
☛ A sound produced due to a combination of several tones is called a Note.
☛ Noise is unpleasant to the ear while music is pleasant to the ear.

Music and Noise, both are closely related to the waveform produced by any musical instrument..

☛ Music and Noise, both are subjective quantities.
☛ The waveform of musical sound is Regular, Smooth, Continuous, and Periodic.

☛ Whereas the waveform of noise is irregular, harsh, discontinuous, and non-periodic.

➧ Consider the following waveform (violin and Tuning fork) same frequency same amplitude but a different waveform.

Characteristics of Sound - Quality or Timber
One of the Characteristics of Sound – Quality or Timber

Difference between – Amplitude, Pitch, and Waveform (Infographics)

Characteristics of Sound - Amplitude, Pitch, Waveform
Characteristics of Sound – Amplitude, Pitch, Waveform

Top One Liner about the Characteristics of sound

1. The SI unit of Frequency?
Answer – Hertz (Hz)

2. What is the SI unit of Intensity?
Answer – Watt / m^2

3. The amount of energy passing through a unit area is called_
Answer – Intensity

4. Loudness is what type of quantity?
Answer – Subjective Quantity

5. The Sound produced from two different musical instruments distinguished by theirs?
Answer – Quality or Timber

6. The waveform of a Noise is?
Answer – irregular, harsh, and discontinuous

7. The Quality of Timber depends on?
Answer – Waveform

8. The Rich quality sound is said to be more __?
Answer – pleasant

9. Loudness is what type of quantity?
Answer – Subjective Quantity

10. Number of waveforms produced per unit of time is called _?
Answer- Frequency

11. High pitch sound corresponds to a -?
Answer – High frequency

12. The voice of males and females can be distinguished by -?
Answer – Pitch

13. What is the unit of loudness?
Answer – Decibel (dB)

14. Softest sound that can be heard?
Answer – 0 dB

15. What is the Intensity of the softest sound?
Answer – 10^ -12 watt / m^2

16. Name the characteristics of sound which depends on amplitude?
Answer:- Loudness

Frequently Asked Questions (FAQ) on Characteristics of Sound

Q1. What are the characteristics of sound?

Answer: The 3 main characteristics of sound are Pitch. Height and quality.

Q2. The loudness is related to which characteristics of sound

Answer: The loudness is related to Amplitude.

Q3. Quality is the characteristics of sound which distinguishes between?

Answer: Two different musical instruments

Q4. Characteristics of sound which depend on frequency?

Answer: Pitch

Q5. Name the characteristics of sound which depends on amplitude.

Answer: Loudness

Source of this article – NCERT

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