A mixed analog-digital hybrid for speech enhancement purposes

The paper presents and evaluates a hybrid implementation of a low complexity algorithm for speech enhancement, the adaptive gain equalizer (AGE). The AGE is a subband based time domain method for instantaneous boosting of speech. By a combination of digital analysis and analog synthesis, the main advantages of the digital and analog domains are utilized. The hybrid solution is implemented on a printed circuit board and evaluated in real-time. The development time of the proposed solution was very short, the solution is flexible, robust, has high signal bandwidth in the signal chain and does not require a voice activity detector (VAD). Furthermore, the solution is not restricted by quantization errors in the signal chain and does not require a high speed digital signal processor (DSP) for analysis. Informal listening tests and signal-to-noise ratio (SNR) measures verify excellent speech enhancement performance and quality.