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How Sound Reaches You
Vibrating source
An object vibrates and becomes the source of sound
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Compressions & rarefactions
The vibration sets up a longitudinal wave in the medium
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Travels through a medium
The disturbance carries energy from source to listener
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The ear perceives it as sound (pitch and loudness)
- Sound
- A form of energy produced by vibrating objects.
- Medium
- The material (solid, liquid or gas) through which sound propagates; sound cannot travel in vacuum.
- Sound wave
- A longitudinal mechanical wave of alternating compressions and rarefactions.
- Wavelength
- The distance between two consecutive compressions or two consecutive rarefactions.
- Frequency
- The number of density oscillations at a point per second; unit hertz.
- Time period
- The time for one complete oscillation; inversely related to frequency.
- Amplitude
- The maximum change in density compared to the average density.
- Speed of sound
- Distance a point on the wave travels in unit time; v = wavelength × frequency.
- Echo
- A reflected sound heard again after at least 0.1 s.
- Reverberation
- The persistence of sound due to multiple reflections in a hall.
- Ultrasonic / infrasonic
- Sound above 20 kHz / below 20 Hz, outside the human audible range.
Revise, Reflect, Refine
Work through the questions below to revise, reflect on, and refine what you learned.
