O'Connor Kevin N, Tam Majestic, Blevins Nikolas H, Puria Sunil
Department of Mechanical Engineering, Stanford University, Stanford, CA 94305, USA.
Laryngoscope. 2008 Mar;118(3):483-90. doi: 10.1097/MLG.0b013e31815b0d9f.
To investigate the significance of tympanic membrane collagen fiber layers in high frequency sound transmission.
Human cadaver temporal bone study.
Laser Doppler vibrometry was used to measure stapes footplate movement in response to acoustic stimulation. The tympanic membrane was altered by creating a series of slits and applying paper patches to isolate the effects of specifically oriented collagen fibers. Three groups of membrane alterations were evaluated: 1) circumferentially oriented slits involving each quadrant to primarily disrupt radial fibers, made sequentially within superior-anterior, inferior-anterior, inferior-posterior, and superior-posterior quadrants; 2) the same slits made in the reverse order; and 3) radially oriented slits from the umbo to the annulus to primarily disrupt circumferential fibers. For each group, measurements of the middle-ear cavity pressure, ear canal pressure, and stapes velocity were made each time the tympanic membrane was altered.
Regardless of the order in which the circumferentially oriented slits were made, there was a consistent decrease in stapes velocity above 4 kHz for the third and fourth cuts compared to the control. The mean decrease in the range of 4 to 12.5 kHz was 11 dB for the third patched slit and 14 dB for the fourth patched slit (P < .01). Radially oriented slits appear to produce smaller effects.
Radial collagen fibers in the tympanic membrane play an important role in the conduction of sound above 4 kHz.
探讨鼓膜胶原纤维层在高频声音传导中的意义。
人体尸体颞骨研究。
采用激光多普勒振动测量法测量镫骨足板在声刺激下的运动。通过制造一系列切口并贴上纸片来改变鼓膜，以分离特定取向胶原纤维的影响。评估了三组膜改变情况：1）在每个象限制作圆周方向的切口以主要破坏放射状纤维，依次在上前、下前、下后和上后象限进行；2）以相反顺序制作相同的切口；3）从鼓膜脐部到鼓环制作放射状切口以主要破坏圆周纤维。对于每组，每次改变鼓膜时都测量中耳腔压力、耳道压力和镫骨速度。
无论圆周方向切口的制作顺序如何，与对照组相比，第三和第四次切口后，4kHz以上的镫骨速度持续下降。第三次贴补切口在4至12.5kHz范围内平均下降11dB，第四次贴补切口平均下降14dB（P <.01）。放射状切口似乎产生的影响较小。
鼓膜中的放射状胶原纤维在4kHz以上声音的传导中起重要作用。
