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Physics Behind the Drums

Mukul Kulkarni

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What is sound?

  • When an object vibrates, it causes movement in sounding air molecules
  • From momentum, it causes a chain reaction with the nearby molecules
  • The chain reaction are the sound waves produced
  • Sound keeps going until it runs out of energy.

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So how does the tightness and the size of the drum, affect the sound produced?

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Methodology

  1. Calculated the volume of the drums
  2. Loosened the drums all the way so there is some tension but not much.
  3. Recorded the frequency for every half turn

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How to find the frequency

  1. I press “Collect” after I hit the drum with a stick.
  2. I go into the “Insert” tab
  3. Press “Additional Graphs”
  4. Press “FFT Graph”
  5. The highest amplitude frequency bar in the bar graph is the frequency of the trail

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Data

  1. Calculated the volume of the drums
  2. Loosened the drums all the way so there is some tension but not much.
  3. Recorded the frequency for every half turn

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Drum 1 (1981.56 in3)

Drum 2 (1130.97 in3)

Drum 3 (671.32 in3)

No turn

60 Hz

60 Hz

95 Hz

1/2 Turns

80 Hz

100 Hz

215 Hz

1 Turn

100 Hz

175 Hz

225 Hz

1 1/2 turns

215 Hz

N/A

N/A

1

2

3

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Significance

  • Proves that there is a relation between the tightness and the size of the drum to the size produced.
    • The tighter the drum, the higher frequency
    • The bigger the drum, the lower the frequency
  • Bigger drums are useful for lower frequencies to produce a thicker, heavier tone, while smaller-sized drums are useful for a brighter, lighter tone.

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More Analysis

  • There is much more to analyze to fully understand how drums work.
  • There are two heads on a drum
  • Both heads can be tensioned to produce different sound.
    • If both and the top are tuned to same tension they will produce sustain the tone is long but volume is low
    • If top head is looser than the bottom, the drum is louder and rings longer
    • If the bottom is tighter, there is minimal ring but flat tone.

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References:

“Music / Science KS2: How Drums Make Sound.” BBC Teach, BBC, 21 Nov. 2019, https://www.bbc.co.uk/teach/class-clips-video/music--science-ks2-how-drums-make-sound/z6wc8xs.

Robrt60. “6. Tuning the Resonant Drumhead – What, Why and How?” IDrumTune, 10 Feb. 2021, https://www.idrumtune.com/tuning-the-resonant-drumhead-what-why-and-how/.

“The Structure of the Drum How Sound Is Produced.” The Structure of the Drum:How Sound Is Produced - Musical Instrument Guide - Yamaha Corporation, https://www.yamaha.com/en/musical_instrument_guide/drums/mechanism/mechanism003.html.

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