Critial Band In marine mammal hearingEdit
Critical Band is a measure of frequency discrimination based on the ability to detect a signal embedded in noise. At some point, as the bandwidth of masking noise is narrowed, the signal becomes far easier to detect; i.e. the detection threshold drops sharply. Noise bandwidth at that point is the critical band. The critical ratio estimates critical bands based on the signal power/noise power ratio. Critical ratio and critical band measurements indicate toothed whales such as sperm whales, beaked whales and dolphins are generally better than most mammals at detecting signals in noise.
Water is dark and dense compared to terrestrial habitats yet all mammals need to eat, move and breed in order to survive. Sound is believed to be the fundamental sensory and communication channel in the oceans. Ocean mammals evolved abilities to utilize a very broad spectrum of acoustic range; more than any other mammalian order.
Ketten, D. R. (1992). The marine mammal ear: specializations for aquatic audition and echolocation. In The evolutionary biology of hearing (pp. 717-750). Springer New York.