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Real-Time DSP Implementation of an Acoustic-Echo-Canceller with a Delay-Sum Beamformer

Real-Time DSP Implementation of an Acoustic-Echo-Canceller with a Delay-Sum Beamformer

Todd Goldfinger
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Traditional telephony uses only a single receiver for speech acquisition. If the speaker is standing away from the telephone, the signal will be weak and there will be interference sources from room reverberation. In addition, there is acoustic echo coming from the loudspeaker, which further interferes with the signal of interest. This research investigated the combination of common solutions to these problems. Electronic beamforming steered an array of microphones within software to enhance the signal power. Echo cancellation removed the echo coming from the loudspeaker. In combination these processing techniques can greatly enhance user experience.


Summary

This master's thesis presents a practical real-time implementation that combines a delay-sum beamformer and acoustic-echo-canceller to improve far-field speech capture in telephony. The reader will learn how microphone-array beamforming and adaptive echo cancellation interact and how they were implemented and evaluated on real-time DSP hardware.

Key Takeaways

  • Implement a delay-sum beamformer to spatially enhance microphone-array signals.
  • Design and integrate an adaptive acoustic-echo-canceller to remove loudspeaker echo in hands-free telephony.
  • Combine beamforming and echo cancellation while managing interaction effects such as residual echo and double-talk.
  • Optimize algorithmic and implementation trade-offs for real-time embedded DSP platforms (latency, complexity, and fixed-point issues).
  • Measure performance using objective metrics (e.g., SNR/ERLE) and evaluate robustness in reverberant and noisy environments.

Who Should Read This

Graduate students, DSP engineers, or system designers working on hands-free audio, teleconferencing, or embedded real-time signal processing who need practical guidance on beamforming and echo cancellation integration.

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Topics

Audio ProcessingAdaptive FilteringReal-Time DSPFFT/Spectral Analysis

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