Detecting Bass in a wav-file
You should be more clear about Detecting Bass.

Bass instrument detection (i.e. polyphonic pitch tracking) and Bass Drum detection (to compute "rhythmic features" or tempo/BPM) are two different tasks. I'll assume you're talking about the latter.

I recommend looking at the open source music-analysis library called librosa, you can do tempo analysis in one line, on audio you've read into memory. You can also use the computed beats to compute various other beat-synchronous features:

import librosa
y, sr = librosa.load(librosa.util.example_audio_file(),sr=None)
tempo, beats = librosa.beat.beat_track(y=y, sr=sr)
print(tempo)
print(beats)


Links to digest:


https://github.com/librosa/librosa/blob/master/examples/LibROSA%20demo.ipynb
http://librosa.github.io/librosa_gallery/