Assignment 1 – Noise Reduction

My roommate and I bought an elliptical trainer about a year ago, and as its parts get old, now it always makes obnoxious noises every time we use it. Here is an audio footage of my roommate using the elliptical trainer in the background and me watching an Oreo tasting video on YouTube:

For this assignment, I thought it would be interesting to see how well the noise can be reduced using Audacity, the audio editing software that I am most familiar with. By performing noise reduction over and over again, it was exciting for me to explore how the correction of irrelevant “background” signals can actually turn the foreground into noise.

First, I had to sample the noise just by itself, as shown in the following snippet:

Then, I performed noise reduction on the entire recording using the default parameters in Audacity (Sensitivity = 6.00, Frequency Smoothing (bands) = 3):

Here is what it sounds like after 1 noise reduction:

After 5 iterations:

After 10 iterations:

After 25 iterations:

After 40 iterations:

After 50 iterations:

Throughout 50 iterations, I could see from the waveform that the amplitudes are reduced, and the few seconds of “pure noise” at the beginning is almost completely erased. After the 50th iteration, the lady’s words are basically incoherent.