Telephones are increasingly being used in noisy environments such as cars, airports and undergraduate laboratories! The aim of this project is to implement a real-time system that will reduce the background noise in a speech signal while leaving the signal itself intact: this process is called speech enhancement.

~ Professor Paul D. Mitcheson, Imperial College London Department of Electrical & Electronic Engineering, 2016.

This 3rd year project involved understanding Real-Time Digital Signal Processing and putting it into practice on a Texas Instruments DSP Starter Kit (TMS320C6713 DSK). The diagram below shows 3 spectograms. A spectogram is effectively a photograph of sound; a visual representation of a sound’s frequency distribution over time. First is noisy sound, then the filtered version, and finally clean speech for comparison.

Spectograms that show speech with reduced noise from a lynx helicopter

The final report is available on GitHub. To sum up, these are the goals achieved towards the end of the project.

Lab 5: IIR Filtering

Objectives accomplished:

  • Learned to design IIR (Infinite-Impulse Response) digital filters using MATLAB.
  • Implemented the IIR filter using the C6713 DSK system in real-time.
  • Measured the filter characteristics using a spectrum analyzer.

Lab 5 Report is available on GitHub.

Project: Speech Enhancement through noise reduction

Objectives accomplished:

  • Implemented triple buffering: input, processing, and output buffers.
  • Implemented various noise estimation and noise reduction techniques,
  • Compared their performance and chose parameters that produced the best audible speech enhancement.