How to make audio processing with an ideal filter by using python/matlab?

For example, the audio recorded is using a sampling frequency of 2000Hz with added noises. 1) Plot its spectrum analysis. 2) Design a single band-reject filter to cancel the noise and obtain the original audio. - must be in time domain. - build 2 31-point low pass windowed-since filter. (fc is based on the noise identified) - convert one of the filters to high pass filter using spectral inversion - design a single-stage band-reject filter using low pass and high pass filters. 3) Is the filter stable?