Conchiglia marina en
From "Physics, Waves, Music": a website about the physics of waves and sound, acoustics of musical instruments, musical scales, harmony and music.
| AI-translated from Italian. Original page: Conchiglia_marina |
A seashell is nothing but a resonant cavity.
When we hold it to the ear we obtain a cavity whose volume has a set of natural resonance frequencies (see the sections on standing waves in 3D, on resonant cavities, and on natural frequencies and resonance).
The ordinary background noise of the surroundings (which is always present) is filtered by the cavity, which emphasises some of its frequencies over others. Which frequencies are emphasised depends on the overall size of the cavity and on other details of its geometry.
| The noise we hear is therefore a hiss in which some frequency bands are especially present (a so-called "coloured" noise, like the pink noise in the example). Listen to the audio below, synthesised in the laboratory. The popular explanation that in a seashell you hear the waves of the sea it came from is therefore, however poetic, completely without physical foundation. |
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Further reading and links
- If you are curious about the unusual name given to this noise ("pink"), visit the section different types of noise to discover the origin of this synaesthetic name.
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