Visualises the amplitude spectrum of the direct cosine transform of the latest 8196 audio data points. Also evaluates polyphony, and fundamental frequencies using the method Anssi Klapuri developed during his PhD (see 'about' in the app for further details). The polyphony estimation seems to work relatively well for one and two simultaneous notes and occasionally get three simultaneous notes correct as well. Due to the implementation, an integer multiple of the actual fundamental frequency is of