I worked in the laboratory of Dr. Micheal L. Dent, an associate professor in the psychology department at the University at Buffalo, N.Y., for a few years as I was earning my undergraduate degree in Animal Behavior. I was interested in studying birds, and Dent was interested in studying acoustic communication in animals.
Acoustic communication refers to hearing. Other ways that animals can communicate include visual, olfaction, touch, thermal, and some can communicate even through electromagnetic fields. In Dent? lab we used operant conditioning and positive reinforcement to measure birds’ abilities to detect, discriminate, identify and localize sounds by training them to peck keys. In the past, Dent has worked with budgerigars, starlings, canaries (multiple strains), Japanese quail, zebra finches, and barn owls. Now she is working with budgerigars and zebra finches.
One interesting occurrence she discovered was that parakeets and zebra finches exhibit the cocktail party effect. Yes ?the cocktail party effect, not cockatiel.
“The cocktail party effect is the problem that we humans and animals both face when trying to identify a sound-producing object in a cacophony of other sound-producing objects, all reaching the eardrum at the same exact time,?Dent explained. When you’re at a loud cocktail party, you turn your head towards the speaker you want to hear to compensate, essentially making the signal really loud at one ear while the background noise remains equally loud at both ears.
“Parakeets and zebra finches both face the same problems we do, and they are able to overcome them as we do,?Dent said. Animals are also better at it then humans when the signal that is hidden in a noisy background has a different set of interaural intensities. Since we have two ears, the sound will be perceived slightly different by each ear, depending on the volume, location and speed of the source. The sound will reach one ear first due to our head placement.
“Birds are able to do this as well, even though their heads are much smaller than ours, resulting in smaller interaural differences in sounds at the two ears,?she said. So the time it takes a sound to reach our second ear, is relatively long compared to how long a sound takes to reach the second ear of a bird. Since birds?heads are so much smaller than ours the sound travels less of a distance, and it was thought that they have a harder time deciphering which way the sound is coming from because the sound reaches both ears at almost the same time. However, this is not the case.
“Interestingly, humans are better at this for speech sounds than for pure tones and our birds are better at this for birdsong than for pure tones,?Dr. Dent added.
What else is remarkable is that we have our ?ar flaps?to help focus the sound, whereas birds just have holes in their head. “Pinna create big spectral cues for sound localization, and without them localization becomes much more difficult,?Dent said. “It is also impressive to do this with small heads and closely spaced ears. Yet, it is not a problem for the birds.?lt;/span>
Next time you are communicating with your pet bird, watch to see if they tilt their heads towards you. “If so,?Dent said, “they may be having difficulty hearing or understanding you.?She recommends that you speak up and get rid of background sounds to better communicate with your bird.
Something else that is interesting in regards to hearing in birds is that when humans listen to loud sounds, the cells responsible for hearing die off and we experience hearing loss. “This also happens naturally as we age,?Dent said. “Interestingly, birds that lose those cells re-grow them in a few weeks so that their hearing is totally restored to normal.?lt;/span>
This is very beneficial as you can imagine for large parrots that acoustically communicate by screaming over long distances. This means that birds don’t experience age-related hearing loss like humans do. An old bird hears just like a young bird.
“Birds like an acoustically rich environment,?Dent concluded. Her birds in the lab who have social contact with others learn the operant task in their experiments much faster than less stimulated birds. “Their calls are also richer,?she said. If you cannot be around to talk to your bird a lot during the day, she recommends that you put on the radio or a CD for stimulation.
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