brespa bug Naïve Random Extraction (5 sec) waveform logmel logmel freq-wise max nocall, no event => mislabeling logmel freq-wise max aware extraction noisy event / call => sometimes works, other times fails. logmel freq-wise max aware extraction with removing lower frequencies bug brespa Using logmel spectrum, extract audio chunks which contain logmel frequency-wise max intensity over the threshold. Because almost of all Bird call frequencies range from 1 ~ 8 kHz, get the better chunks for training via removing lower frequencies (~ 300Hz). Variable extraction length, 5 - 10 sec, also helps to get a good signal, meanwhile 2D models are well generalized to variable length. threshold