Device and process for measuring acoustic reflectance

摘要

A device and a process for analysis of acoustic reflectance directs acoustic energy for a range of frequencies including resonance frequencies of the object being analyzed. The device detects waves reflected by the object to produce what is called an acoustic reflectance curve. The electronic signal applied to an acoustic transducer at each frequency is gradually increased in amplitude to a desired amplitude. After applying the signal for a period of time at the desired amplitude, the amplitude is gradually decreased. This technique reduces noise that would otherwise occur if a signal of the desired amplitude was applied directly. The signal applied to the acoustic transducer also may be scaled according to a measured response of the device to open air, i.e., without any expected reflectance. Normalizing the signal applied to the acoustic transducer rather than the signal received from a microphone increases the dynamic range of the device. The device also may require operation for several sweeps through a range of incident frequencies in order to ensure proper user technique is used. When the data for the several sweeps is analyzed, the best result of the several sweeps may be stored as the output.