| 摘要 |
The invention is directed to an apparatus for taking measurements in the ear, having a positioning aid enabling a probe head (10) of the apparatus to be properly aligned in a user's auditory canal (12). The apparatus of the present invention comprises a source of radiation (24) emitting energy particularly in the visible region, a photodetector (30) suitable for sensing this radiation, and an associated evaluation unit and, where applicable, an indicating unit for representing the alignment of the probe head in the auditory canal (12). This canal receives the radiation from the radiation source (24), with part of the radiation being scattered back into the probe head (10) and sensed by the photodetector (30). In this arrangement, the radiant power sensed is dependent on the mean distance between the reflecting tissue and the probe head (10), with a minimum radiant power corresponding to a correct alignment of the probe head (10) to the rear auditory canal (12) and hence to the tympanic membrane (38). The output signal of the photodetector (30) preferably controls the frequency and/or volume of an audible signal informing the user of the optimal alignment of the probe head (10), so that the repeat accuracy of the measurement results is improved.
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