Respuesta :
doppler effect!!!!!!!!!!!!!!!!!!!!!!!!!!!!! ! ! ! ! ! ! ! ! ! ! ! !
Answer:
the Doppler effect
Explanation:
The doppler effect is what we called the effect that happens when the wavelength or frequency of a sound changes because the observer is moving relatevily form the object, could be moving closer or moving further away, but the wavelenght and the frequency changes alongside with the movement.