Spline-based continuous-time pitch estimation

Pitch-synchronous speech coding algorithms can achieve low bit rates without compromising the quality. However, the effectiveness of pitch-synchronous coding depends strongly on the ability to estimate precisely and reliably the fundamental period of the speech signal. We present a novel pitch postprocessing method that significantly improves the accuracy and reliability of pitch estimation. In contrast to the classical schemes, the pitch is treated as a continuous function in time and amplitude. B-Spline signal processing, half wave rectification, and multi-stage, multi-resolution optimization are essential parts of the procedure. The performance of the method is evaluated objectively and subjectively using the Waveform Interpolation coder. The objective results show that, for voiced segments, the method significantly (60% on average) decreases the energy of the unvoiced component estimate compared to using an unprocessed pitch. Listening tests show a 90% preference of speech generated using our postprocessor over speech generated using a conventional method.