Chapter 6: Musical Instruments
Why instruments sound the way they do — vibration, resonance, frequency, timbre — and the great musicians behind them.
Original notes — ready CBSE (NCERT, English Medium) • Class 8 • Arts • Book: Kriti
Chapter 6: Musical Instruments — EG's own notes, in simple words
Book: Kriti (CBSE, Class 8) | Chapter 6 | Section: Music | Medium: English
Diagram (labels are printed on the image): A labelled diagram of sound science: a vibrating string, sound waves travelling through air, and a hollow body resonating.
A young musician with a tabla and a bansuri, learning how makers build instruments and players master them.
What the chapter is about
Music is both an art and a science, and this chapter proves it. Sound is produced because of vibrations: when an object vibrates, it creates sound waves that travel through a medium — air, water and so on — to reach our ears. Through resonance, sound is amplified or made louder: in a percussion instrument, the hollow body or cavity resonates and amplifies the sound, just as a ringing bell's sound reaches a listener through vibrating air molecules.
Frequency is the number of vibrations per second. A faster vibration produces a higher frequency and a higher pitch — tightening the tuning peg of a sitar increases its tension and vibrating frequency, so the pitch rises. High-frequency sounds, like a bat's, sit at one end; low-frequency sounds, like an elephant's, at the other. Timbre is the 'tone' or 'colour' of a sound: it varies with the material of the instrument, its construction and its playing technique, which is why different instruments sound different even on the same note.
Making instruments, and the musicians who play them
Instrument makers are essential for the survival of traditional art forms, and scientific principles are used in making instruments. The chapter follows a drum being made: the maker works a log of wood into a cylindrical shape, creates the drum's head, fixes it onto the wooden drum, and ties straps to help with tuning. The teacher's note suggests inviting a local instrument maker to school for a live demonstration.
Musicians often become synonymous with their instruments. Annapurna Devi (1927–2018), born Roshanara Khan, daughter of Baba Allauddin Khan of the Maihar Gharana, played the surbahar — a plucked string instrument often called the 'bass sitar', deeper and lower than the sitar and suited to elaborate alaap. Though the surbahar was considered physically demanding and uncommon for women, she mastered it; her father considered her his finest student, and though she did not perform publicly, her students included flautist Hariprasad Chaurasia and sitarist Nikhil Banerjee. Pannalal Ghosh (1911–1960) made his name synonymous with the bansuri (Indian flute); a disciple of Baba Allauddin Khan, he popularised the flute as a concert instrument. Activity 6.1 asks students to find instrument names, Activity 6.2 to map an instrument, and Activity 6.3 is a crossword whose clues include: a string instrument of hard wood with more than a hundred strings (santoor), the percussion used for dhrupad (pakhawaj), Ustad Zakir Hussain's instrument (tabla), Pandit Ravi Shankar's instrument (sitar), a four-string bowed instrument (violin), a pot-shaped baked-clay percussion (ghatam), a long-necked four-string finger-played instrument (tanpura), a keyboard wind instrument sounding through reeds (harmonium), a bamboo wind instrument with 6 or 7 finger holes (bansuri), a set of water-filled ceramic or metal bowls (jaltarang), Ustad Bismillah Khan's wind instrument (shehnai), and a folk bow instrument of Rajasthan (ravanhatta).
The same physics explains a sitar's tuning peg and a temple pillar's note: vibration, frequency and resonance work everywhere.
If your town has an instrument maker, watch them work — you will see science (tension, cavity, material) become music.
Key Terms
- Vibration — The back-and-forth movement of an object that produces sound waves.
- Resonance — The amplification of sound by a hollow body or cavity vibrating along with the source.
- Frequency — The number of vibrations per second; faster vibration means higher frequency and higher pitch.
- Timbre — The tone or colour of a sound, depending on material, construction and playing technique.
- Surbahar — A plucked string instrument, the 'bass sitar', deeper and lower than the sitar.
- Bansuri — The Indian bamboo flute, popularised as a concert instrument by Pannalal Ghosh.
- Santoor — A string instrument of hard wood such as walnut or rosewood, with more than a hundred strings.
- Pakhawaj — The percussion instrument used to sing the dhrupad style.
- Ghatam — A pot-shaped Indian percussion instrument made of baked clay.
- Jaltarang — A percussion instrument of ceramic or metal bowls filled with water.
Remember
- Sound = vibrations travelling as waves through a medium to our ears.
- Resonance in a hollow body amplifies sound; frequency fixes pitch — faster vibration, higher pitch.
- Timbre differs with material, construction and technique.
- Drum-making: log → cylinder → head fixed → tuning straps.
- Annapurna Devi — surbahar; Pannalal Ghosh — bansuri; Zakir Hussain — tabla; Ravi Shankar — sitar; Bismillah Khan — shehnai.
Exam Tip / Common Mistake
Common mistake: saying a louder sound is a higher sound. Loudness (volume) and pitch (frequency) are different — a soft high squeak and a loud low drum prove it.
Chart / Table: Sound science and the crossword instruments
| Point | Detail |
|---|---|
| Vibration | Object vibrates → sound waves → medium → ears |
| Resonance | Hollow body/cavity vibrates along, amplifying sound |
| Frequency | Vibrations per second; faster = higher pitch |
| Timbre | Tone/colour; depends on material, construction, technique |
| Santoor / Pakhawaj | 100+ strings, hard wood / dhrupad percussion |
| Tabla / Sitar | Zakir Hussain / Ravi Shankar |
| Violin / Tanpura | 4-string bowed / long-necked, 4 strings, fingers |
| Harmonium / Bansuri | Keyboard wind, reeds / bamboo, 6–7 holes |
| Ghatam / Jaltarang | Baked-clay pot / water-filled bowls |
| Shehnai / Ravanhatta | Bismillah Khan / Rajasthani folk bow instrument |
Practice set — try it yourself
- How is sound produced, and how does it reach our ears?
Hint: Vibration creates waves travelling through a medium. - What does tightening a sitar's tuning peg change, and why?
Hint: Tension and frequency, so pitch rises. - Why do two instruments sound different on the same note?
Hint: Different timbre — material, construction, technique. - Name the drum-making steps in order.
Hint: Log to cylinder, head made, head fixed, straps tied. - Which instrument did Annapurna Devi play, and why is it called a bass sitar?
Hint: Surbahar — deeper and lower than the sitar.
Questions with Answers
- Explain vibration, resonance and frequency with one example each.
Vibration: a struck string moves back and forth, making sound waves. Resonance: a percussion instrument's hollow body vibrates along and makes the sound louder. Frequency: tightening a sitar peg raises vibrations per second, so the pitch rises. - What is timbre, and what three things change it?
Timbre is the tone or colour of a sound. It varies with the material used for the instrument, the construction of the instrument, and its playing technique. - Describe how a drum is made, step by step.
The maker works a log of wood into a cylindrical shape, creates the drum's head, fixes the head onto the wooden drum, and ties straps to help with tuning. - Why was Annapurna Devi remarkable as a surbahar player?
The surbahar was physically demanding and uncommon for women, yet she mastered it so completely that her father, Baba Allauddin Khan, considered her his finest student; her students included Hariprasad Chaurasia and Nikhil Banerjee. - Solve three crossword clues: the dhrupad percussion, the water-bowl percussion, and Bismillah Khan's instrument.
Pakhawaj, jaltarang and shehnai respectively.
Extension questions — go deeper
- A bat's sound and an elephant's sound differ in frequency. Which is higher, and how would you prove it without seeing the animals?
The bat's sound is higher frequency — faster vibrations, higher pitch. Even blindfolded, the squeak sounds 'higher' than the rumble, because pitch is heard directly. - Design a classroom experiment that shows resonance using two identical bowls or a string and a box. What would you change, and what would you listen for?
Pluck a string held in air, then with one end on a hollow box: the box version sounds louder. The only change is the resonating cavity, so resonance explains the difference. - Why does the chapter call instrument makers 'essential for the survival of traditional art forms'?
Without makers, there are no instruments to play, no repair knowledge and no new players learning the craft — the art form loses its tools and its teachers. - Pannalal Ghosh 'popularised the flute as a concert instrument'. What had to change for a folk instrument to reach the concert stage?
Technique, repertoire and acceptance: a disciple of a great guru, a concert-worthy sound, and audiences willing to hear the bansuri as a solo classical voice. - Pick any two crossword instruments and compare them on three points: family (string/wind/percussion), material, and a famous player.
For example, sitar (string, wood, Ravi Shankar) versus shehnai (wind, wood/metal reed, Bismillah Khan) — different families, different materials, both carried by a single legendary name.
- Sound = vibration + medium + ears.
- Resonance amplifies; frequency sets pitch; timbre colours.
- Drum-making steps in order.
- Annapurna Devi, Pannalal Ghosh and their instruments.
- Crossword instruments and their players.
How to use this page: Read the summary, say the Key Terms in your own words, then try the practice set without looking. Use the Questions with Answers to check yourself afterwards. Ask your teacher or parent to check your answers.