Comparison of Frontal and Mastoid Bone-Conduction Thresholds in Various Conductive Lesions Unoccluded and occluded bone conduction (BC) and Sensorineural Acuity Level (SAL) thresholds at the frontal bone and the mastoid process were compared on 60 subjects with conductive hearing loss. The results were based on calibrated norms obtained on 32 subjects with normal hearing and validated on 10 cases with sensorineural ... Research Article
Research Article  |   December 01, 1969
Comparison of Frontal and Mastoid Bone-Conduction Thresholds in Various Conductive Lesions
 
Author Affiliations & Notes
  • Donald D. Dirks
    University of California School of Medicine, Los Angeles, California
  • Carolyn M. Malmquist
    University of California School of Medicine, Los Angeles, California
Article Information
Research Articles
Research Article   |   December 01, 1969
Comparison of Frontal and Mastoid Bone-Conduction Thresholds in Various Conductive Lesions
Journal of Speech, Language, and Hearing Research, December 1969, Vol. 12, 725-746. doi:10.1044/jshr.1204.725
History: Received November 5, 1968
 
Journal of Speech, Language, and Hearing Research, December 1969, Vol. 12, 725-746. doi:10.1044/jshr.1204.725
History: Received November 5, 1968

Unoccluded and occluded bone conduction (BC) and Sensorineural Acuity Level (SAL) thresholds at the frontal bone and the mastoid process were compared on 60 subjects with conductive hearing loss. The results were based on calibrated norms obtained on 32 subjects with normal hearing and validated on 10 cases with sensorineural hearing loss. The mastoid BC thresholds for the entire conductive group were more depressed than comparable frontal measurements, but the average difference was only five dB. The threshold data for subjects with surgically confirmed middle-ear lesions (N = 38) were analysed in greater detail by dividing the group by frontal-mastoid differences and observed physical changes within the middle ear. Approximately 20% of the group showed frontal-mastoid differences that exceeded the normal range, and these cases had either malleus fixation or an ossicular discontinuity due to incus necrosis or absence of the incus. Average results for 17 cases with stapes fixation suggested that there were no frontal-mastoid differences and that both BC curves were somewhat similarly influenced by the middle-ear impairment. The SAL and occluded BC thresholds at the frontal bone were always in close agreement and differed from the unoccluded frontal-bone measurements for the conductive cases by the amount of the average occlusion effect observed for normals. The advantages of unoccluded bone conduction at the frontal bone are stressed, and the possible use of a comparison of BC thresholds at the two sites for diagnostic purposes is suggested.

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