$5$ Design Matlab program for the application of speech noise cancellation. In a speech roconding system the noisy environment is at a sampling rate of $8000H{z}_2.$ Assuming that the rcoonded spech contains information within $1800Hz,$ and design a lowpass filter to remove the noise between $1800Hz$ and the Nyquist limit$.$ You can use Matlab functions firwd and filter. Plot the input and output after filtering process and their single side spectrum. If you can not find a speech signal, construct a signal consisted of sinusoidal signals with different frequencies and amplitudes. The frequencies need to be in the range $1000-1800Hz.$ In order to put the noisy effect, you can generite Gaussian random noise.