Tympanometry. ASHA Working Group on Aural Acoustic-Immittance Measurements Committee on Audiologic Evaluation.
Most of the available tympanometric data have been generated with instruments that measure immittance magnitude at 226 Hz. These limited measurements are valuable in evaluating middle-ear pathologies such as effusion and tympanic-membrane perforations but are not always adequate in evaluating pathologies of the ossicular chain such as otosclerosis and ossicular discontinuity. In response to this shortcoming, manufacturers of the newest generation of immittance devices have incorporated variable frequency or click probe signals. With these new instruments, it is possible to evaluate the middle-ear transmission system over its normal range of functioning. These new instruments also are computer based. If two-component, multifrequency immittance measurements are input to the computer, it then becomes possible to analyze and plot the data in many forms. Presently, the technology has outpaced the clinical understanding of these complex measures. The intent of this tutorial was to focus on areas of tympanometry not widely discussed in previous writings. The first two sections on terminology and instrumentation encourage clinicians to know their instruments and to use standardized terminology in communicating data. Much of the remaining information focused on the new generation of multifrequency immittance systems. Examples of normal and pathological tympanograms were plotted at a number of frequencies and in a variety of formats. In the beginning, tympanometric measures will be cumbersome, but as research begins to focus on these new measurements, the best frequency range and frequency interval and the best plotting formats will be identified. In conducting these studies, the procedural (e.g., rate and direction of ear-canal pressure change and the number of successive tympanometric runs) and computational (calculation at peak or 0 daPa and calculation of ear-canal contributions) variables must be specified if the data are to be universally applicable. Once these questions are answered, tympanometric measures with computer-based instruments will be rapid and informative. Enough data do not yet exist to incorporate multiple-frequency tympanometry into screening programs. Future research will need to address the efficacy of more complex tympanometric screening procedures. It is possible that the 226-Hz screening procedure will prove most efficient in school-aged children, the majority of whom whould be identified as having middle-ear effusion by the present procedure, or in the case of ossicular-chain abnormality, would have a significant hearing loss.(ABSTRACT TRUNCATED AT 400 WORDS)
D000158:Acoustic Impedance Tests / Q000295:instrumentation / Q000379:methods / Q000592:standards; D000162:Acoustics; D000328:Adult; D002138:Calibration; D002648:Child; D006801:Humans; D009626:Terminology as Topic