Our graduates from first degree programmes at the Faculty of Mechanical Engineering and Robotics won third place at the Saul Walker Student Design Competition held by the Audio Engineering Society (AES) for the project that originated from their Bachelor theses.
Piotr Cieślik and Karol Nowakowski currently pursuing their Masters at the Faculty of Computer Science, Electronics and Telecommunications received awards for the project: Acoustic Camera – Project of microphone array in MEMS technology, integrated with Android mobile devices. Participation in the competition posed a real challenge for the students as in order to make it to the finals, they had to present a working prototype to the jury.
Piotr Cieślik handled the design and development of a microphone array, which resulted in his thesis “Acoustic camera – Project of Microphone Array in MEMS Technology” being written and successfully defended. Karol Nowakowski was responsible for integrating the microphone array using Bluetooth communication as well as for designing and developing a mobile app for Android devices. As a result, he also wrote and defended his Bachelor’s thesis on “Acoustic camera – visualisation of sources of sound by means of a microphone array”. Both theses were written under the supervision of Jakub Gałka, DSc.
The students aimed to design and build a compact acoustic camera whose low production cost could make this technology more available to regular users. The idea originated in observations of acoustic holography, which is a new trend in sound measurements. The method involves visualisation of sources of sound and sound pressure produced by these sources by superimposing the audio signal from the microphone array onto the signal received from the video camera.
According to Piotr Cieślik: “This technology is currently very expensive (the average cost of an acoustic camera being around USD 20 000). We wanted to design a microphone array that would be affordable as well as compact and easy to use. Therefore, one of the core assumptions behind our project was that it should be possible to integrate the camera with a smartphone, the camera’s dimensions being more or less the size of a telephone or tablet.”
After a number of numerical simulations which confirmed that there was a real chance that such a camera would work, the designers created a microphone array using MEMS microphones, which – while both affordable and compact – produced a signal of satisfactory quality. As a next step, the signal obtained from the microphones was pre-processed by an ARM microcontroller, which filtered the signal and formed sound beams for improved quality and precision of the source location. Finally, the signal from the microphone array was sent via Bluetooth and received by a smartphone. The application should enable users to select a correcting filter of their choice and ultimately view the sources of sound seen as a heat map, superimposed on the signal from the video camera. The working system together with a sample shot have been presented below.
Commenting on their success, Piotr Cieślik added: “After the prototype phase, once all the testing had been done, we concluded that it might be worth introducing our project to a wider audience at AES 148th Convention – an international event organised in Vienna by Audio Engineering Society. The project proved to be innovative enough to give us third place at the Saul Walker Student Design Competition”.
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