Physical Audio Digital Filters
This system allows to insert physical objects in audio digital signal processing chains, filtering the sound with the acoustic impulse response of any solid measured in real-time. Physical objects are modeled as a linear time-invariant system, which is then used as an audio filter. By interacting with the object or with the measuring hardware it is posible to dynamically modify the characteristics of the filter. The impulse response is obtained correlating a noise signal injected in the object through an acoustic actuator with the signal received from an acoustic sensor placed on the object. The system is implemented in Max using native objects only. Correlation and convolution are implemented in the frequency domain (using poly and pfft). This enable running multiple physical filters of maximum lenght (4096 samples) in parallel without overloading the CPU. The system support further creative use beyond audio filtering, such as tangible signal patching and sound spatialization.