Wideband absorbance tympanometry using pressure sweeps: System development and results on adults with normal hearing

Abstract

A system with potential for middle-ear screening and diagnostic testing was developed for the measurement of wideband energy absorbance ͑EA͒ in the ear canal as a function of air pressure, and tested on adults with normal hearing. Using a click stimulus, the EA was measured at 60 frequencies between 0.226 and 8 kHz. Ambient-pressure results were similar to past studies. To perform tympanometry, air pressure in the ear canal was controlled automatically to sweep between −300 and 200 daPa ͑ascending/descending directions͒ using sweep speeds of approximately 75, 100, 200, and 400 daPa/ s. Thus, the measurement time for wideband tympanometry ranged from 1.5 to 7 s and was suitable for clinical applications. A bandpass tympanogram, calculated for each ear by frequency averaging EA from 0.38 to 2 kHz, had a single-peak shape; however, its tympanometric peak pressure ͑TPP͒ shifted as a function of sweep speed and direction. EA estimated at the TPP was similar across different sweep speeds, but was higher below 2 kHz than EA measured at ambient pressure. Future studies of EA on normal ears of a different age group or on impaired ears may be compared with the adult normal baseline obtained in this study.

Comparisons of transient evoked otoacoustic emissions using chirp and click stimuli

“…As a result, the measured waveform at the probe corresponded to the incident pressure waveform in the absence of any reflections. This calibration approach reduces standing-wave effects, and was previously used in studies of reflectance (Liu et al, 2008), wideband acoustic stapedius reflex (Keefe et al, 2010), and CEOAEs (Goodman et al, 2009).…”

Specification of absorbed-sound power in the ear canal: Application to suppression of stimulus frequency otoacoustic emissions

“…The aural absorbance a is the ratio of acoustic energy absorbed by the middle ear (and in the ear canal when significant wall loss is present) from a single click stimulus to its incident sound energy. It is expressed in terms of pressure reflectance by (Liu et al, 2008) a…”

Wide band pressure and velocity (p-v) tympanometry with calibrated sound intensity micro-probes

“…Recent advancements in wideband absorbance tympanometry [4], while extending the experimental model based on equation (4) [5] where the rigorous expression of the energy current immittance has been given as i…”

“…It is worth to point out that at present, tympanometric signals are obtained only with a pressure microphone, so no direct measurement of the immittance function of the ear is accomplished: this process would require, in fact, the acquisition of the concatenated air particle velocity signal in addition to the acoustic pressure one. The possibility of using well calibrated p-v sound intensity microprobes [3] has been recently demonstrated by two of the authors of the present paper [5], in connection with recent developments of wide band excitation tympanometry and the concept of Energy Absorbance (EA) [4]. The p-v approach to audiometric measures is possible thanks to the development of MEMS sensors, whose size makes them optimal to be used in such particular applications; it can be safely stated that this approach is the key to discover an entire new horizon to energetic audiometry.…”