A rarefaction click occurs when the initial movement of a transducer diaphragm is:

A rarefaction click occurs when the diaphragm of a transducer moves away from the tympanic membrane, creating a rarefaction phase in the sound wave it generates. In acoustics, the term "rarefaction" refers to the decrease in pressure that occurs when a sound wave expands or an area of compression is allowed to return to a lower pressure state. This movement away from the tympanic membrane creates a space that leads to a drop in air pressure and is essential for the perception of sound.

In auditory testing or monitoring, understanding the behavior of transducer diaphragms is critical because different movements result in different types of sound waves, which in turn can elicit varying responses from the auditory system. Thus, recognizing that the rarefaction click is specifically characterized by the diaphragm moving away from the tympanic membrane helps in comprehending the mechanics of sound transmission and the principles of electroacoustic systems utilized in neurophysiological monitoring.