Two researchers at the University of South Alabama in Mobile are running experiments on gerbils in order to study how humans tell sounds apart at a basic level. As Nature reports, they found that the rodents were able to distinguish between basic phonemes like "ee" and "oo".
In their experiments, the researchers presented Mongolian gerbils with two feeder cups: one to the right and one to the left. One vowel sound, pre-recorded and played back repeatedly at intervals of one second, signals that the food is in the left-hand cup. A different vowel sound indicates food in the right-hand cup. The gerbils could learn this rule relatively quickly in tests with pairs of ten different vowel sounds, the researchers say.
Like humans, gerbils vary in their abilities. Two of the six gerbils in Sinnott's group, named Jackson and Washington, were able to distinguish many vowel pairs about nine times out of ten. Others performed less well – Lincoln was able to discriminate 'aw' as in 'paw' from 'ah' as in (American) 'pot' little better than the 50% level of random choice. But all the gerbils did better than chance for all vowel sounds tested.
The researchers also found that gerbils' ability to distinguish sounds didn't change as they aged. Nature says the find suggests age-induced hearing impairment in humans may be due to external factors and may therefore not be inevitable.