When two sound waves of equal amplitude and opposite phase (180 degrees out of phase) overlap and combine, they undergo a process called "destructive interference." In destructive interference, the peaks of one wave align with the troughs of the other wave, and vice versa. As a result, the positive displacements of one wave cancel out the negative displacements of the other wave, and the two waves effectively nullify each other.
The result of canceling out a sound wave with another sound wave through destructive interference is a reduction in the overall sound level or complete silence at specific points where the interference occurs. This effect is commonly used in noise-canceling technologies, where an external sound wave is produced with the opposite phase to cancel out ambient noise, providing a quieter or more isolated environment.
It's important to note that destructive interference only occurs under specific conditions, such as when the waves have the same frequency, amplitude, and are precisely 180 degrees out of phase at the point of interference. In other cases, where the waves have different frequencies or are not perfectly out of phase, partial interference or no interference may occur.