ENGR 4323/5323: Digital and Analog Communications
Due TBA
Speech Compression
The objective of this project is to compress a speech signal so it can be transmitted faster, use less channel bandwidth, and storage. The price of compression is deterioration in the sound quality of the speech. For each compression ratio, you will need to objectively evaluate the quality of the compressedsignal by calculating the signal to noise ratio (SNR) and subjectively by listening to the compressed signal. Download the signal in the sound file “Music” from the course’s website. The sampling rate of the signal is 44100 samples per second. The samples are quantized such that each sample is represented by 16 bits. In this project you will reduce the required transmission channel bandwidth by reducing the number ofsamples per second and the number of bits required for each sample.
1)What is the size of the signal in megabits?
2)Compress the signal by down sampling and quantization using the following parameters
Method 1: 8000 sample/second with 8 bits/sample
Method 2: 8000 sample/second with 4 bits/sample
Method 3: 8000 sample/second with 4 bits/sample (use µnonuniform quantization)
Method 4: 2000 sample/second with 8 bits/sample
Method 5: 2000 sample/second with 4 bits/sample
3)Play the compressed signalsin part 2. Compare the sound quality of the compressed signals to the original signal for each method.
4)Calculate the quantization error for each method.
5)Calculate the signal to noise ratio in dB for each method.
In your project report state the objective of the project and answer the required tasks in sentences and paragraphs. You can use equations and plots to explain your approach to accomplish the tasks. Codes should be included at the end of the project report as Appendix.
Bonus: Develop a compression method of your own and compare it to the above methods.