To date three studies have empirically tested the

In all cases, there was some evidence that the low-amplitude vocalizations, which had equal or greater note variability, degraded more rapidly than the high-amplitude vocalizations. However, these tests are limited in interpretive power because Triassic Period relied on the ability of a microphone to record each signal at varying distances rather than directly testing the abilities of receivers to perceive and respond to each signal. Direct tests of the auditory capabilities of receivers are essential for determining a signal's active space.