Tone, Musical Note, Timbre and Octave

Introduction

In the previous topic, we studied how humans perceive sound as pitch and loudness. But when we listen to music, we notice something more. Different musical instruments may produce sounds of the same loudness and same note, yet they do not sound exactly the same.

This happens because musical sounds have special qualities such as tone, musical note, timbre and octave.

Tone

A tone is a sound of a single frequency.

A tuning fork produces nearly a single frequency sound. Oral whistling can also produce a sound close to a single frequency.

Examples of Tone

• Sound produced by a tuning fork
• Sound produced by oral whistling

Since a tone contains only one frequency, it sounds simple.

Musical Note

A musical note is not a sound of only one frequency. It is a combination of a lowest frequency and some higher frequencies.

The lowest frequency present in a musical note is called the fundamental frequency. The higher frequencies present along with it are called overtones.

Together, the fundamental frequency and overtones produce a rich and pleasant sound.

Examples of Musical Notes

• Sound produced by plucking a tanpura string
• Sound produced by singing
• Sound produced by musical instruments such as sitar, sarangi and veena

Difference Between Tone and Musical Note

Tone	Musical Note
A sound of a single frequency	A combination of fundamental frequency and overtones
Simple sound	Rich and pleasant sound
Example: tuning fork or whistling	Example: singing or plucking a tanpura string

Fundamental Frequency

The fundamental frequency is the lowest frequency in a musical note.

It mainly decides the basic pitch of the musical note. For example, if two notes have different fundamental frequencies, we hear them as different notes.

Overtones

Overtones are the higher frequencies present along with the fundamental frequency in a musical note.

Overtones make the sound richer and more pleasant. They also help in making one musical instrument sound different from another.

Timbre

Even when two different instruments play the same note at the same loudness, they sound different. This special quality of sound is called timbre.

Timbre helps us identify the source of sound.

Example

Suppose a flute, an ektara and a tabla play the same note at the same loudness. Still, we can recognise which sound is from the flute, which is from the ektara and which is from the tabla. This is because their timbre is different.

Why Do Different Instruments Have Different Timbre?

The timbre of an instrument depends on its:

• shape,
• material,
• construction,
• pattern of overtones,
• intensity of overtones.

Because of these differences, each instrument produces a unique sound quality.

Figure: Tone, Musical Note and Timbre

Explanation of the Figure

The figure shows that a tone has a single frequency, while a musical note has a fundamental frequency along with overtones. Timbre is the quality that makes different instruments sound different, even if they produce the same note at the same loudness.

Octave

An octave is the interval between two notes in which one note has double the frequency of the other.

For example, if one note has a frequency of \(200\,Hz\) and another note has a frequency of \(400\,Hz\), then these two notes are separated by one octave.

\(400\,Hz = 2 \times 200\,Hz\)

Indian Musical Instruments and Rich Sound

Indian string instruments such as the sarangi, sitar and veena often use extra strings. These extra strings enrich the combination of frequencies and help produce rich musical sounds.

Indian drums such as the tabla and mridangam also produce a rich variety of sounds.

Syaahi in Tabla and Mridangam

Indian drums like the tabla and mridangam have a black patch at the centre of the drum head membrane. This patch is called the syaahi.

The syaahi changes the vibration of the membrane. Due to this, these instruments can produce a rich variety of sounds and better tonal control.

C. V. Raman and Acoustics

Sir C. V. Raman won India’s first Nobel Prize in Science for discovering the Raman Effect in light. He also made important contributions to acoustics, the science of sound.

He studied Indian percussion instruments such as the tabla and mridangam to understand how they produce rich and nuanced sounds.

Important Terms

1. Tone

A tone is a sound of a single frequency.

2. Musical Note

A musical note is a combination of fundamental frequency and overtones.

3. Fundamental Frequency

The lowest frequency present in a musical note is called the fundamental frequency.

4. Overtones

The higher frequencies present along with the fundamental frequency are called overtones.

5. Timbre

Timbre is the quality of sound that helps us distinguish between sounds produced by different instruments or sources.

6. Octave

An octave is the interval between two notes where one note has double the frequency of the other.

7. Syaahi

Syaahi is the black patch at the centre of the drum head membrane of instruments like tabla and mridangam.

Important Points

• A tone is a sound of a single frequency.
• A tuning fork produces nearly a single frequency sound.
• A musical note contains a fundamental frequency and overtones.
• The fundamental frequency is the lowest frequency in a musical note.
• Overtones are higher frequencies present along with the fundamental frequency.
• Overtones make musical sounds rich and pleasant.
• Timbre helps us recognise different sound sources.
• Different instruments have different timbre due to their shape, material and construction.
• An octave is formed when one note has double the frequency of another note.
• Indian instruments such as sitar, sarangi, veena, tabla and mridangam produce rich musical sounds.
• The syaahi in tabla and mridangam helps produce a rich variety of sounds.

Conclusion

Tone, musical note, timbre and octave help us understand the richness of musical sounds. A tone has a single frequency, while a musical note contains a fundamental frequency and overtones. Timbre is the quality that makes different instruments sound different even when they play the same note. An octave is formed when one note has double the frequency of another note. These ideas help us understand why musical instruments produce such rich and unique sounds.