Loudness in the Laboratory, Part II: Non-Steady-State Sounds

The human auditory system conveys information about temporal variations in music, speech, and environmental sounds. Most of the sounds in daily life are temporally varying and non-steady state. Sounds in a temporal stream within a certain time interval are integrated by the auditory system, and information is extracted from these data (Fraisse 1978). An object can be recognized and differentiated in because it has its own specific pattern of temporal variation, different from that of other objects. Jones (1978) described that an auditory perception of a pattern is a meaningful succession within an event and conveys information about the outer world. Music, speech, and noise have unique patterns of temporal variation of sound energy. In daily life, the physical variation of a sound itself is seldom paid much attention: people generally listen to sound to grasp the information that it conveys, such as the meaning of the speech, the sources of machinery sound, the location of the sound sources, the melody of music, and so forth (Garner 1974).