If household appliances are noisy, many people may speculate that this is a problem with the engine, but this may not be the case-there are many "injustices". The pantograph recently developed by the Institute of Acoustics of the Chinese Academy of Sciences can accurately determine where the problem came from. Because the pipes and other components arranged around the engine may also be the culprit of making noise. This is a problem that it is difficult for people to distinguish with their own direct hearing, and it cannot be distinguished using traditional single microphone measurements. Only the pantograph can return an innocent engine. Because in the test of many noise sources, the experimenters found that there was a lot of misdiagnosis based on a single microphone without using a phase meter.
Make the sound appear
The so-called pantograph is an instrument that can take pictures of the sound field. The phase meter can accurately capture the sound sources at different positions by measuring the spatial information of sound propagation, and can effectively find and distinguish each sound source under complex mixing conditions. This can not only give people an intuitive sound field image, accurately measure the indicators of each sound source, but also have intuitive and convenient analysis methods.
Although most animal sounds come from the mouth, in terms of machinery and equipment, the source of noise is not so single. There are often multiple sound sources in a device, and each sound source contributes to the total sound. If you want to solve the noise problem of machine equipment, it is critical to accurately measure the starting sound position.
According to Yang Yichun, a researcher at the Institute of Acoustics, the phase meter contains a series of advanced measurement techniques and new signal processing algorithms. It uses a microphone array to measure the sound field distribution within a certain range. It can be used to measure the position of sound emitted by an object and the state of sound radiation. It displays an intuitive image in a manner similar to a meteorological cloud image, that is, acoustic imaging measurement, giving people an intuitive Acoustic image.
The measurement accuracy of the pantograph is first closely related to the distribution of the array elements on the microphone array. The optimized array has a low virtual image effect, that is, the phenomenon of false sound sources will not occur. In addition, the measurement accuracy of the pantograph is also related to the advantages and disadvantages of the acoustic imaging algorithm. The optimized algorithm can obtain an accurate sound field cloud picture and has a good human-computer interaction function.
When the pantograph is working, the sound pressure distribution of a certain area in front of the array detection is displayed on the computer screen. The depth and width of the color scale on the screen reflect the dynamic range of the sound field, which can be adjusted with the mouse, or the frame can be adjusted. The size of the lens can also be adjusted with the scroll wheel. The program can lock the instantaneous sound to capture the impact sound; it can also be quickly switched to detect the transient sound field. In other words, the detection device can display real-time changes in the sound of the detection area by connecting to the computer.
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