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Acoustic Properties of Different Cartilage Reconstruction Techniques of the Tympanic Membrane
Author(s) -
Mürbe Dirk,
Zahnert Thomas,
Bornitz Matthias,
Hüttenbrink KarlBernd
Publication year - 2002
Publication title -
the laryngoscope
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.181
H-Index - 148
eISSN - 1531-4995
pISSN - 0023-852X
DOI - 10.1097/00005537-200210000-00012
Subject(s) - cartilage , sound transmission class , materials science , sound pressure , piezoelectricity , acoustics , biomedical engineering , anatomy , composite material , medicine , physics
Abstract Objectives/Hypothesis The use of cartilage in reconstruction of the tympanic membrane has been established especially in cases such as tubal dysfunction and adhesive processes. Cartilage offers the advantage of higher mechanical stability compared with membranous transplants but may alter the acoustic transfer characteristics of the graft. Apart from material properties, it can be assumed that, also, the microsurgical reconstruction technique might influence the sound transmission properties of the reconstructed tympanic membrane. The purpose of the study was to investigate the acoustic transfer characteristics of different cartilage transplants being typically used in different reconstruction techniques of the tympanic membrane. Methods Cartilage plates of different thicknesses (1.0, 0.7, 0.5, and 0.3 mm), cartilage palisades, and cartilage island transplants of varying size were investigated by means of an ear canal–tympanic membrane model. In contrast to former single‐point measurements, sound‐induced vibrational amplitudes of the entire transplant were measured by scanning laser Doppler vibrometry (measuring points, n = 133) (PSV‐200, Polytec, Waldbronn, Germany). Frequency response functions (displacement vs. sound pressure) of all measured points were determined in the frequency range of 200 Hz to 4 kHz for the different transplants. Results Cutting thick cartilage transplants into thin plates or palisades decreased the first resonance frequency and increased its amplitude, reflecting improved sound transmission properties of the transplant. From an acoustical point of view, the 0.5‐mm cartilage plate seems preferable compared with the palisade technique. Cartilage island techniques showed vibration characteristics superior to plate or palisade techniques. Conclusions Apart from material characteristics, the sound transmission properties of the reconstructed tympanic membrane are strongly influenced by the reconstruction technique. The choice of the surgical technique should consider requirements based on mechanical stability and acoustic transfer characteristics of the transplant.