The notion of reverberation is linked to a measurement of the time it takes for a sound to decrease by 6o dB. Etymologically, the word comes from the Latin verb reverberare, meaning “to strike back, to reflect.” In the displacement of a sound from its source to the ear, only a small part of the sound energy travels in the most direct way. A large portion of the sound energy follows indirect paths, as it is reflected on the ground and the environment of the milieu: walls, ceiling, facades. Since these routes are longer, reflected sound energy takes more time than direct energy to reach the ear. This discrepancy is the basis of reverberation. […] The phenomenon that we just described in time can also be characterized in space: if we place a constant-power sound source in a closed or semi-closed space and measure the intensity of the sound source while moving away from it, we can see that the sound normally decreases within a certain distance. Beyond that distance, the intensity does not decrease further. This distance, which depends on the space, is called “critical distance” (CD).”
Psychology and Physiology of Perception
In everyday practice, reverberation is omnipresent; even if measurements indicate weak physical variations, the correspondent hearing perception may be strong. The he average listener tends to valorize reverberation when he or she becomes aware of it, sometimes having the impression that sounds are interminable. In fact, because of air and material absorbtion, reverberation is always mediated. If reverberation was infinite – if sounds did not fade away and were never absorbed– a single sound would “circulate” constantly and the sound level would increase to infinity, making all communication impossible. Although limited, the reverberation of large spaces such as churches or concrete and glass buildings may illustrate this lack of intelligibility.
On the other hand, in a totally absorbant milieu it is difficult to be aware of space. In an atmosphere of quietness and absecence of sound, our impression quickly becomes unpleasant. We can hear our own heartbeats, and body sounds acquire incredible proportions. These impressions can be experienced in an anechoic chamber (an experimental space in which all reverberation is eliminated): the space seems to be squeezed in on itself, narrow and stifling, even if its physical volume is large.
Blind people listen for subtle variations in the reverberations from the sound of their canes in order to find their way and to detect a wall or an angle they are approaching. From this point of view, large, empty places are unsuitable for good perception of the sonic space. Reverberation frequently plays a role in our perceptions:
- the perception of the presence of something or someone beside oneself (through the modification of the reverberated field)
- the feeling of “collectivity” and the sharing of social communication (through the envelope it creates)
- the propensity toward a narcissistic attitude as a sound mirror in situations of individual sound productions (singing or whistling in a bathroom, for instance).
Sociology and Everyday Culture
Reverberation is socially perceived as an indication of solemnity and monumentality. It signifies volume and large size. This monumentality can be sensed as functional and inherent to the use of some locations (cathedrals, concert halls) or as unpleasant and residual for others (train station halls, concrete underground parking garages). Reverberation is also perceived in terms of “resonance,” a term referring, in everyday speech, to reverberation in general. Through its architectural representation, reverberation is easily associated with various functions of power (religion, justice).’
In the domain of culture, reverberation is synonymous with a crowd. It is linked to large ritual or solemn gatherings in churches or sacred caves. Reverberation also plays a role in large press conferences, where, paradoxically it reduces the intelligibility of the message. In large spaces, a poor sound system may emphasize the shortcomings of natural reverberation.
Every epoch is characterized by specific types of reverberation linked to specific places, but a history of this effect remains to be written. Even if we consider the example of cathedrals, which are the oldest large enclosed spaces in the West, it is extremely difficult to have a precise idea of the diverse acoustics they contained because of the evolution of interior decorations and arrangements. The original reverberation is still unknown, and would be quite difficult to reconstitute.
Textual and Media Expressions
Reverberation is abundantly used in media expressions: horror and science-fiction films, westerns, and advertisements emphasize the connection of reverberation to large spaces, even if the location is often not adapted to such an effect (desert, interplanetary space). Reverberation can also refer to sociological aspects emphasized in the preceding locations (power, justice).
Augoyard, Jean-Francois & Torgue, Henry, eds. “Reverberation”, Sonic Experience: A Guide to Everyday Sounds. Montreal: McGill-Queens University Press. 2005. pp 111- 117.
Image 1: Al Held, Black Nile III, 1971. Via ArtNet
Image 2: Al Held, Roberta’s Trip, 1985. Acrylic on canvas, 243.8 × 365.8 cm. Via Brooklyn Rail