What is it?
The concept of "Camera Obscura" (or dark chamber) originates from optics. It refers to a phenomenon where light from an external scene passes through a hole to project an inverted image onto a dark interior surface.
Imagine the typical photographic darkroom. Or rather, a child’s room with a small window overlooking a one-way street. Here's how it manifests:
- The sunlight reflecting off the bodywork of the car on the left, or the light from its headlights, enters through the open window.
- Inside the room, photons (light) bounce off the right wall, thus reversing their apparent direction.
- As the car moves from left to right, its light shifts towards the center of the room.
- Before reversing again as it exits the scene.
In this illustration, the effect is represented flat, but it is applicable in two dimensions.
But did you know that a similar principle can be applied to the field of sound?
The effect, applied to sound
In acoustics, the effect that we might call a "sound chamber" is based on an analogy: a small opening can invert the spatialization of sounds coming from the outside.
I personally noticed this effect in my children’s room, which has a small window overlooking a one-way street. Here's how it manifests:
- When a car approaches from the left, its sound enters through the open window.
- Inside the room, the sound bounces off the right wall, thus reversing its apparent direction.
- As the car moves from left to right, the sound seems to shift towards the center of the room.
- Before reversing again as it exits the sound scene.
In this illustration again, the effect is represented flat, but it is applicable in two dimensions.
This play of inversion and acoustic spatialization recreates a unique sound experience, comparable to an inverted image in a dark chamber.
This phenomenon, although still little known in this form, could reveal intriguing possibilities for sound design, architecture, and art.
What else?
We also know that the Doppler-Fizeau effect exists for light. Applicable in astronomy:
- When the source approaches the observer, the light appears bluer because the wavelengths shorten and the frequency increases.
- When the source moves away from the observer, the light appears redder because the wavelengths lengthen and the frequency decreases.
In my opinion, sight and hearing are the two most important senses in life. But then, I wonder if such effects (Doppler or Obscura) exist for touch, taste, and smell?
Your opinion matters
And you, what would you call this fascinating acoustic effect? Can you imagine ways to use it in your environment or creations? Share your ideas in the comments!
Article written to explore the links between sound and optics. For any questions, feel free to comment!
