Introduction - If you have any usage issues, please Google them yourself
Read the bluesky3.wav file (the content is for boys "blue sky, white clouds"), mix 50Hz hum into the voice data, design a band digital filter with Kaiser window, passband cutoff rate 45Hz, band cutoff Frequency 49 and 51, the minimum attenuation of the stop band is A2=50dB, and the sampling frequency is 8000Hz.