Alligators CAN hear.
More Info: Alligators hearing is very different from the hearing of humans and other animals. This is because they spend just as much if not more of their time underwater. Because of this, their hearing needs to be specially adapted to receive signals through water as well as on land. Though not entirely understood, there are a number of ways researchers have stated this could happen.
Alligators have shown that they have excellent hearing through both the air and the water. Alligators as well as most other animals have little hairs on the insides of their ears that pick up on any sounds they hear. Though this is the same for many species, the way the sound is transmitted to the inner ear of the animal can differ.
Studies on Alligator Hearing
Because alligators spend so much time lounging around underwater, scientists have been prompted to conduct many studies on alligator hearing. Through these studies they have not only determined that alligators hear very well both underwater and out of the water, but they have also determined a few reasons why they think this is so.
One of the ways scientists think alligators funnel sound into their ears underwater is through the bones in their skull. Another way scientists think alligators do this is through the use of skin receptors in their faces. These receptors are called dome pressure receptors or DPRs. This conclusion was reached based on the fact that the frequencies used most often in alligator communication are below the optimal range of hearing in alligators.
Alligator hearing sensitivities in both air and water peak at around 800 Hz. Coincidently, this is also the frequency at which alligator hatchlings chirp at. Though their hearing sensitivity peaks at around 800 Hz, they respond to a broad range of tones. Depending on whether the alligator is underwater or above water, the tone ranges that they respond to differ. The tones they can hear underwater range from 100 Hz to 2,000 Hz. Above the water, the tones they hear have a much broader range from about 100 Hz to 8,000 Hz.
Scientists also measured how other things might impact the hearing of an alligator. One of these things was how an air bubble trapped inside the ear might affect the hearing of an alligator. Studies found that these had no effect on the alligators hearing, thus it is not an important adaptation to their hearing.
The Journal of Experimental Biology
ALLIGATORS TUNED INTO WATER
US National Library of MedicineNational Institutes of Health
Amphibious auditory responses of the American alligator (Alligator mississipiensis).
151st ASA Meeting, Providence, RI
Intensity Of The American Alligator (Alligator Mississippiensis) Vocal Courtship Display: Evidence For Saccular (Non-Cochlear) Hearing In Crocodilian Vocal Communication