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EEL 4102 - Spring 2020 - MATLAB Assignment 5
EEL4102 – Fall 2019 – Matlab Assignment 5
For this homework, you will be filtering noise from a sound recording. Assignment is broken into simple
steps you can follow. Please follow instructions carefully and remember that you will only upload one
workspace (*.mat) file. Make sure to name the clean_speech variable correctly.
1) Download the Matlab workspace from the link provided in Canvas. Move the
downloaded file to the same folder as your script to make things simpler.
2) Load the downloaded workspace into Matlab.
You can use the following command: load noisy_speech.mat
3) You will see two variables. fs = 16000Hz is the sampling frequency and noisy_speech is
the vector which contains a recording of a spoken sentence with a very harsh noise.
4) You can use “soundsc” command to play the speech file: soundsc(noisy_speech,fs)
NOTE: If you are working through USF AppGateway (Citrix), you can’t use soundsc
command because it runs on USF servers, not your computer. You will either need a
computer that runs a local copy of Matlab, or save the sound file, download it to your
computer and play it there. See the following link to see how to save an audio file. You
can use the *.vaw format.
5) Determine what frequency band your desired signal is in, and what frequency band your
noise occupy. You can do a frequency analysis (using FFT) to determine the noise
frequency band. You will not be able to see your desired signal because noise will
NOTE: Feel free to use the internet for determining the frequency range of your desired
signal (human speech).
6) Design a filter to filter out the noise using any method you would like, Matlab’s
filterBuilder tool for example. Filter the noisy_speech signal to obtain a clean speech
signal. Name this variable as clean_speech.
7) Do another frequency analysis (using FFT) to the filtered signal and compare it with the
frequency domain of noisy signal. Verify that your desired signal is visible in the
frequency domain plot.
8) Listen to your resulting sound file with soundsc(clean_speech,Fs). The speech signal
should be clean without any harsh noise, something you wouldn’t mind hearing on a
phone call. See the note under 4) if you are using Citrix.
9) When you are happy with the sound quality, save your workspace with:
10) Upload your workspace file, which includes all the variables as well as your filter.
11) You won’t upload any .m files for this assignment.