Coupling of FM Systems to Individuals With Unilateral Hearing Loss This study examined the attenuation characteristics of five FM system sound delivery options for a group of 10 adults and 15 children (5–13 years). Sound delivery options included a tube-fitting, lightweight headphones, a CROS earmold with tubing, a CROS earmold with a snap-ring, and a standard snap-ring earmold with a ... Research Article
Research Article  |   February 01, 1992
Coupling of FM Systems to Individuals With Unilateral Hearing Loss
 
Author Affiliations & Notes
  • Judy G. Kopun
    Boys Town National Research Hospital Omaha, NE
  • Patricia G. Stelmachowicz
    Boys Town National Research Hospital Omaha, NE
  • Edward Carney
    Boys Town National Research Hospital Omaha, NE
  • Laura Schulte
    Boys Town National Research Hospital Omaha, NE
Article Information
Hearing Disorders / Hearing Aids, Cochlear Implants & Assistive Technology / Hearing / Research Articles
Research Article   |   February 01, 1992
Coupling of FM Systems to Individuals With Unilateral Hearing Loss
Journal of Speech, Language, and Hearing Research, February 1992, Vol. 35, 201-207. doi:10.1044/jshr.3501.201
History: Received January 22, 1991 , Accepted May 15, 1991
 
Journal of Speech, Language, and Hearing Research, February 1992, Vol. 35, 201-207. doi:10.1044/jshr.3501.201
History: Received January 22, 1991; Accepted May 15, 1991

This study examined the attenuation characteristics of five FM system sound delivery options for a group of 10 adults and 15 children (5–13 years). Sound delivery options included a tube-fitting, lightweight headphones, a CROS earmold with tubing, a CROS earmold with a snap-ring, and a standard snap-ring earmold with a vent. Attenuation was defined as the difference between probe-tube microphone measures of the ear canal resonance and the SPL in the ear canal with each sound delivery option in place. A statistically significant but clinically inconsequential difference in attenuation for the CROS earmold with tubing was noted between adults and children. No significant differences in attenuation for any of the other sound delivery options were noted between adults and children. An investigation of the relationship between magnitude of attenuation and percentage of the ear canal occluded suggests that degree of occlusion is a major factor in determining degree of attenuation provided by a particular sound delivery option. Results also indicate that significant attenuation of high-frequency signals can occur with earmolds commonly considered nonoccluding. Caution should be used in fitting hearing aids or FM systems to individuals with normal high-frequency hearing sensitivity to prevent attenuation of unamplified high-frequency speech information.

Acknowledgments
We would like to thank Kathryn Beauchaine and Dawna Lewis for their helpful comments, and Betsy From for her help in the preparation of this manuscript. We also would like to thank Westone Laboratories, Inc., for their contribution to the fabrication of the earmolds used in this study. This work was supported in part by NIH.
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