The mechanisms described above become obvious when one studies the transference function of the ME, ie the complex interaction between amplitude and phase that exists between the acoustic pressure at the entrance to the inner ear (Pv: pressure within the perilymph at the base of the scala vestibuli) and the pressure at the TM (Pt): Pv/Pt. More about physics (s ee below) Middle Ear transfer function The middle portion of this tube passes through a diverticulum, the guttural pouch, which is considered separately (see 5.3 ). ![]() In effect, ME function (similar to any type of mechanical system) depends on the friction (R) of the ossicular joints, the mass of the drum/ ossicular chain, and the rigidity (K) of the various membranes, ligaments, air volume and so on. The internal auditory tube runs from the rostral wall of the middle ear to the nasopharynx and provides the means for pressure equilibration across the tympanic membrane and mucus clearance from an enclosed space. Anatomy The three auditory ossicles the malleus, incus, and stapes are tiny bones found in the middle ear. These bones play an important role in the sense of hearing by transmitting sounds to the inner ear. Because of the relationship between the surface areas of the TM (area S1 = 0.6 cm2) and the stapes footplate (area S2 = 0.03 cm2), and because of the interaction of the ME levers (the axis of the ossicular chain passes very close to the incudomalleolar joint, but the two arms of this lever are of unequal length, d1/d2 = ~ 1.3), the pressure amplification is theoretically in the order of x26 (approx 28 dB)īeware, however! This calculation must be used with caution, because, due to its mechanical characteristics, the behaviour and the efficiency of the ME varies greatly with varying frequency of sound (f). The bones of the ear, also known as the auditory ossicles, are the three smallest bones in the human body. A recent paper has also suggested the sampling of auditory ossicles (the malleus, incus and stapes) may provide an alternative to the petrous for ancient DNA analyses, as they provide comparable.
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