Hearing
In mammals the cues for hearing are usually based on inter-aural intensity differences, which occur as a result of the diffraction of a progressive sound wave by the head and pinna. They could also be based on inter-aural time differences that are present because of the distance between their two ears. Moles have no pinna so they are thought to hear at low frequencies. In addition to this, their inner ear is unusual for that of a mammal due to the large trabeculation of the posterior ventral skull between the ears. The tympana of the ear lays almost horizontal and the manubrial tips are separated by a distance of 8 mm. The results of several studies confirms that there is good transmission through European mole’s head for a range of low frequencies. Because of this it is expected that there will be acoustic interaction at each tympanic membrane. The results of the study also suggest that the ears of this mole act as balanced, pressure-difference receivers. This system has never been suggested for a mammal in the past, but other reptiles, amphibia, birds, and crickets have been shown to have a direct air pathway between the tympana.
Read more about this topic: European Mole
Famous quotes containing the word hearing:
“Dark night, that from the eye his function takes,
The ear more quick of apprehension makes;
Wherein it doth impair the seeing sense
It pays the hearing double recompense.”
—William Shakespeare (1564–1616)
“I used to be angry all the time and I’d sit there weaving my anger. Now I’m not angry. I sit there hearing the sounds outside, the sounds in the room, the sounds of the treadles and heddles—a music of my own making.”
—Bhakti Ziek (b. c. 1946)
“I do not allow myself to be moved by anything except the law. If there has been a mistake in the law, or if I think there has been perjury or injustice, I will weigh the petition most carefully, but I do not permit myself to be moved by more harrowing details, and I try to treat each case as if I was reviewing it or hearing it for the first time from the bench.”
—William Howard Taft (1857–1930)