Add Bass with Biquad

[jimchen90]

This is a sox dependency reduction task to implement bass (with biquad) filter as #260 using the treble (with biquad) filter as example.

Here is a notebook to compare the coefficients with SoX and Matlab audio toolbox.
A related issue #676

[vincentqb]

Well done so far :)

• Let's add torchscript_consistency_test, see here.
• Please add a description, with link to relevant issues and notebooks.
• Tests are failling

[jimchen90]

I update the code as below:

Add the torchscript test.
In functional.py file, I use the normalized coefficients for biquad function.
In test_sox_compatibility.py file, I add two bass tests: one test sets gain = 30, atol = 1e-4, the other sets gain = 40, atol = 1.5e-4. The details can be seen in #676

[jimchen90]

I update the files with flake8 check.
In test_sox_compatibility.py file, I add only one bass test with atol = 1.5e-4 instead of 1e-4 in treble test. The value atol = 1e-4 works if gain decreases (for example gain = 30)

[vincentqb]

Thanks for working on this! LGTM :)

[vincentqb]

The errors are flaky and unrelated to this PR.

[vincentqb]

@jimchen90 -- can you add a link to the notebook you used for analysis here?

[jimchen90]

@jimchen90 -- can you add a link to the notebook you used for analysis here?

I have added the link in the description.