Echo

With an echo we hear both the original sound source and its reflection, noticing the delay between one and the other. Echo is therefore a particular type of reverberation, from the Latin verb reverberare, to strike back or reflect. It is defined as a propagation effect in which, according to Augoyard and Torgue (2005: 111), “sound continues after the cessation of its emission”. Reverberation occurs when surfaces bounce back or reflect auditory waves. Unlike an echo, though, reverberation is most often perceived as almost simultaneous with the produced sound, a resounding that effectively amplifies through instant diffusion of sound waves. Singing in the shower, for example, we hear our own voice in a louder and seemingly fuller version as it resonates against the hard surfaces of the bathroom. In such enclosed spaces, resonance and reverberation overlap as the harmonics of the original sound are reproduced. By contrast, stepping inside an anechoic chamber is sufficient to recognise the importance of this reflection for our day-to-day hearing; it can be a thoroughly disconcerting experience to be without this resonance of one’s voice, as though it never leaves the body.