LPCNet

LPCNet is a pioneering hybrid neural vocoder that integrates traditional Digital Signal Processing (DSP) techniques, specifically Linear Predictive Coding (LPC), with deep recurrent neural networks (RNN). Developed primarily by Jean-Marc Valin at Mozilla, it represents a significant leap in audio synthesis efficiency, enabling high-quality speech generation at computational loads significantly lower than pure-neural models like WaveNet. By using the LPC coefficients to handle the spectral envelope, the neural network only needs to model the residual excitation signal, which is much easier to learn and requires fewer parameters. As of 2026, LPCNet has become a foundational architecture for low-bitrate speech codecs and real-time Text-to-Speech (TTS) applications on edge devices. It utilizes sparse GRU (Gated Recurrent Unit) layers and 8-bit quantization to achieve real-time performance on high-end mobile CPUs without requiring dedicated GPU acceleration. This makes it ideal for privacy-focused, on-device voice synthesis and low-latency communication protocols where bandwidth and power are constrained.