Sound reflection . It is a phenomenon that affects the propagation of sound .
A wave is reflected (bounces back to the medium from which it came) when it hits an obstacle that it cannot go through or around.
The size of the obstacle and the wavelength determine whether a wave goes around the obstacle or is reflected in the direction from which it came.
If the obstacle is small relative to the wavelength, the sound will go around it ( diffraction ), whereas if the opposite happens, the sound is reflected ( reflection ).
If the wave is reflected, the angle of the reflected wave is equal to the angle of the incident wave, so that if a sound wave strikes the reflecting surface perpendicularly, it returns on itself.
Reflection does not act the same on high frequencies as it does on low frequencies. The wavelength of low frequencies is very long (they can reach 18 m), so they are capable of surrounding most obstacles; high frequencies, on the other hand, don’t go around obstacles so they cast shadows behind them and bounce them off in front of them.
In acoustics , this property of waves is well known and exploited. Not only to isolate, but also to direct the sound towards the auditorium through reflective plates (reflectors and turntables).
Phenomena related to reflection
- standing waves. A standing wave is produced by the sum of a wave and its reflected wave on the same axis. Depending on how the phases of the incident wave and the reflected wave coincide, modifications will be produced in the sound (increase or decrease in amplitude), so the resulting sound can be unpleasant. Under certain circumstances, the standing wave can cause the room to resonate.
- the echo The original acoustic signal has died out, but the sound is not yet returned as a reflected wave. The echo is explained because the reflected wave reaches the receiver in a time greater than the acoustic persistence.
- The reverb. Reverberation occurs when the reflected waves reach the receiver before the extinction of the direct wave, that is, in a time shorter than the acoustic persistence of the ear.