Consider the audio file speech.wav and read it to MATLAB using the wavread function. The sampling frequency was 44.1 kHz and the samples were coded using a uniform quantizer with 16 bits. You can listen to the audio file using the MATLAB function sound. 1. Apply to the signal a uniform quantizer using 32 levels and 256 levels. For each case determine the signal-to quantization noise ratio. Apply then a non-uniform quantizer using the A law with A = 20 and A = 87.6. And determine the signal-to-quantization noise ratio for these cases. 2. Consider now that the signal is attenuated 10, 20, 30 and 40 dB. For each of these cases, determine the signal-to-quantization noise ratio, considering a uniform quantizer and a non-uniform quantizer (A = 87.6) both with 256 levels. 3. Draw a graph with the results obtained and comment.