# Sound reflection

Reflection of sound . It is a phenomenon that affects the propagation of sound .

Basic idea

wave is reflected (bounces off the medium from which it comes) when it meets an obstacle that it cannot pass through or surround.

The size of the obstacle and the wavelength determine whether a wave surrounds the obstacle or is reflected in the direction from which it came.

If the obstacle is small in relation to the wavelength, the sound will surround it ( diffraction ), however, 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 hits the reflecting surface perpendicularly, it turns on itself.

Reflection does not act the same on high frequencies as it does on low frequencies. The wavelength of the low frequencies is very large (they can reach 18 m), so they are able to go around most obstacles; instead, the high frequencies do not surround the obstacles so there are shadows behind them and bounces in their front part.

In acoustics this property of the waves is well known and used. Not only to isolate, but also to direct the sound towards the auditorium by means of reflective plates (reflectors and tornavoces).

Reflection-related phenomena

• Standing waves. A standing wave is produced by the sum of a wave and its wave reflected on the same axis. Depending on how the phases of the incident wave and the reflected wave coincide, changes will occur in the sound (the amplitude increases or it decreases), so the resulting sound may be unpleasant. Under certain circumstances, the standing wave can cause the room to resonate.
• The echo. The original acoustic signal has been extinguished, but the reflected waveform sound is not yet returned. The echo is explained because the reflected wave reaches the receiver in a time greater than that of acoustic persistence.
• Reverberation occurs when the reflected waves reach the receiver before the extinction of the direct wave, that is, in less time than the acoustic persistence of the ear.