This is a measure of how often a sound occurs in a given subject s daily life. This classification, being based on the sound phenomena and not the causes, suits the needs of a synthesis guideline but would need to be refined to account for auditory constraints. Classes of environmental sounds Figure 1. A broad classification scheme for environmental sounds. By defining two classes of interaction between excitation sources and resonating bodies, i.e., single or multiple excitations, we establish a clear way to link physical models and granular synthesis with mundane sounds.
All terrestrial objects suffer energy loss.
No acoustic object generates unchanging sinusoidal components until infinity, or increases in amplitude after the attack transients have ended. Multiple excitations are produced by physical agents, such as fire or running water, or by biological agents, such as a clapping hand. It is very likely that these cues have been decisive for survival, i.e., the sounds of a predator stepping on leaves have to be discriminated from the same type of sounds produced by a prey. When visual cues are not readily available this becomes a question of life or death. The distinction between human and animal agency only makes sense if applied within a specific social context.