Effect of Changes in Mass on Middle Ear Function

Vibrating systems such as the middle ear are affected by changes in mass. After disease or ear surgery, significant changes in mass may contribute positively or negatively to the postoperative hearing threshold. This article describes experiments in 15 human temporal bones of the addition or reduction of mass on the middle ear transfer function. Measurement of stapes and umbo vibration was performed using a Laser Doppler Vibrometer before and after the addition of different masses at several sites on the tympanic membrane (TM) and ossicular chain. The input was 61 pure tones swept from 147 to 19433 Hz at 80 dB SPL. The addition of mass onto the TM produced varying detrimental effects on sound transmission, depending on the location and amount of mass. The insertion of ventilation tubes, weighing 12 to 17 mg each, produced losses at 1.5 to 5.0 kHz compared with tympanotomy alone. Addition of mass to the umbo and malleus head produced a loss at mid and high frequencies, whereas addition of mass on the incus long process and stapes also produced a high-frequency decrease in stapes displacement. Reduction of TM mass by removal of the epithelium produced an increase, especially at 2.0 to 4.0 kHz.

[1]  C. Fernández,et al.  I The Mechanism of Bone Conduction , 1960, The Annals of otology, rhinology, and laryngology.

[2]  S. Khanna,et al.  Tympanic-membrane vibrations in human cadaver ears studied by time-averaged holography. , 1972, The Journal of the Acoustical Society of America.

[3]  J. J. Grote,et al.  Acoustic transfer characteristics in human middle ears studied by a SQUID magnetometer method. , 1987, The Journal of the Acoustical Society of America.

[4]  I. Tuncer,et al.  Inverted follicular keratosis. , 1993, American journal of otolaryngology.

[5]  H. Johansen Relation of Audiograms to the Impedance Formula , 1948 .

[6]  M. Vlaming,et al.  Studies on the mechanics of the normal human middle ear. , 1986, Clinical otolaryngology and allied sciences.

[7]  G. Ball,et al.  Measurement of umbo vibration in human subjects--method and possible clinical applications. , 1993, The American journal of otology.

[8]  Dr. Gerald Fleischer Evolutionary Principles of the Mammalian Middle Ear , 1979, Advances in Anatomy, Embryology and Cell Biology.

[9]  J. Tonndorf,et al.  Middle ear sound transmission: a field of early interest to Merle Lawrence. , 1986, American journal of otolaryngology.

[10]  R. Ruben,et al.  Hearing results with the use of different tympanostomy tubes: a prospective study. , 1988, International journal of pediatric otorhinolaryngology.

[11]  K Gyo,et al.  Measurement of the ossicular vibration ratio in human temporal bones by use of a video measuring system. , 1987, Acta oto-laryngologica.

[12]  M. Lawrence Acoustic effects of middle ear substitution. , 1960, Transactions - American Academy of Ophthalmology and Otolaryngology. American Academy of Ophthalmology and Otolaryngology.

[13]  J. Tonndorf,et al.  Mechanical aspects of stapedial substitution. An experimental study. , 1966, Archives of otolaryngology.

[14]  K Gyo,et al.  Effect of middle ear modification on umbo vibration. Human temporal bone experiments with a new vibration measuring system. , 1986, Archives of otolaryngology--head & neck surgery.