A New York Times article is making the rounds about how a captive false killer whale has demonstrated a mechanism for attenuating potentially damaging noises. Paul Nachtigall, the principal investigator of the study has conditioned the subject to de-sensitize its hearing in anticipation of an oncoming loud noise.
I had an unfruitful discussion with Paul about this a few years ago during the Marine Mammal Commission Federal Advisory Committee meetings on noise exposures. His position was that blue whale vocalizations were loud enough to deafen dolphins. In theory, yes, but these animals have been cohabiting the same environment for the last 25 million years, I argued, so there is a probability that they had evolved some accommodation.
Terrestrial animals have a governor in our middle ears called the “tensor tympani” that stiffens up the excursion of our ossicles when we are exposed to, or even expect to hear a loud sound (if we see an ironing board falling these muscles kick in before it hits the floor).
These muscles are part of what is responsible for ringing ears after a loud rock concert. They are designed for occasional and temporary protection from excessive, potentially damaging noises. They are not designed for long, chronic, or repeated exposures. So when they are called upon to protect our hearing over extended periods of time they go into spasm – leading to ringing ears.
Dr. Nachtigall is now arguing that this impulse protection could be a “mitigation strategy” for chronic loud noise exposure. What is particularly annoying about his argument is that he believes he has “trained” the animal to respond. (“We have a problem in the world,” Dr. Nachtigall said of the oceanic roar. “And we think the animals can learn this response very rapidly.”)
Now if we could only have the animals pay for this sensitivity training we’d have a great business opportunity here…