耳模和声管长短的声学效果评估

目的：了解耳模和声管长短对声学效果的影响。方法：任选外耳道结构正常的受试者30人（60耳），并按耳印在第二峡部的平均直径≥4．0mm者为甲组，＜4．0mm者为乙组。采用丹麦产Aurical真耳分析仪，运用台台湾产恒升486笔记本电脑在Noah平台下操作，应用同一固定的助听器，按常规真耳测试方法分析耳模及声管在长短不同的A、B、C三种类型下的声学效果，即A型为耳模与声管等长且距离鼓膜约1．0cm,C型耳模及声管均比A型短0．5cm,B型的声管与A型等长而耳模与C型等长，实验中分别测量A、B、C型耳模在250、500、750、1000、1500、2000、3000、4000、6000Hz时的介入增益值，即A、B及C值，并将测量结果进行SAS软件分析，结果：甲组在250、500Hz处的A、B值较C表显著性差异（P＜0．05），在3000、4000、6000Hz处A值与C值均有高度显著性差异（P＜0．01），B值与C值均有显著性差异（P＜0．05），在750、1000、1500和2000Hz处A、B和C值无明显变化（P＞0．05）；乙组中A、B值较C值仅在250、500Hz有显著性差异（P＜0．05），在其它频率三者间无显著性差异（P＞0．05）。结论，当外耳道较为宽大时，增加声管的长度可以提高低频和高频的增益，当外耳道较为狭窄时，增加声管的长度仅能提高低频的增益。

Assessment to the Acoustic Effect of the Length of the Earmould and Tubing

Objective To know the acoustic effect of the length of theearmould and tubing. Methods Thirty person(sixty ears) with normal structure of the external acoustic meatus were divided into two groups according to the average diameter of ear impression in the second narrow, which less than4.0 mm is group Ⅱ, the others belonged to group Ⅰ. In additional, three types earmould were made. Type A which earmould is the sane length as tubing is about 1.0cm to tympani membrane, type C which all is 0.5 cm shorter than A, type B which the eamould is the same as C anl the tubing as A. Then the insertion gains were tested with Aurical real ear analyzer in different fiequencies: 250, 500, 750, 1 000, 1 500, 2 000, 3 000, 4 000 and 6 000 Hz. In the end anslyzing the results with SAS soft. Results Group I showed A,B than C had differed significantly in 250, 500Hz(P<0.05), very differed significantly in 3 000, 4000, 6000 Hz(P<0.01), and no differed in the others(P>0.05). GroupⅡ showed A,B than C had differed significantly in 250, 500 Hz(P <0.05) and no in others(P > 0.05).Conclusion Increasing the length may enhance the gain of low and high frequencies when external acoustic meatus is wider, but only low fiequecies when narrow.