Realtime audio filtering in Passive Acoustic Monitoring of Cetacean

AMS (Alsa Modular Synth) is a realtime modular synthesizer and effect processor. AMS gives different kinds of modules useful in PAM (Passive Acoustic Monitoring), avoiding analogic external devices. The proposed example divides the input sound into two paths: - High frequencies out of audibility range (> 18kHz) are filtered through a highpass filter and divided using a pitchScale module; - A bandpass filter cuts out low noisy frequencies (in the proposed example >2kHz) and excludes the higher frequencies already filtered in stage 1. Finally, the two signal paths are blended using a mixer module, where it is possible to adjust different gain levels. The result of using this approach in PAM activities is to improve the audibility of cetacean sound without watching a spectrogram, giving a way to hear also hi frequencies emissions (clicks, burst purse sounds) in real-time