Will also has some good stuff on his website, from himself and a number of his former students:
I’ve switched to using GNU Octave almost exclusively for prototyping (syntactically similar to MATLAB, if you ever find resources for that). I’ve also been looking at using Julia/Jupyter notebooks for more things but the
control packages in Octave cover 90% of my use cases.
Audio Signal Processing by Zölzer is an excellent text (there’s an old pdf floating around the internet), some of it is a little dated covering hardware concerns, but the bulk of it is extremely useful.
DAFX, edited by Zölzer is a cookbook of formulas/algorithms for audio DSP.
More DSP oriented, I have this and this at my desk. The former is more of a reference, the latter is my go-to for implementation details (has a lot of MATLAB code). The chapters on FIR design and sample rate conversion are particularly useful.