Vocoder
A vocoder, short for voice coder, is a class of speech processing devices or software that analyzes spoken input to extract a compact representation of its spectral and prosodic characteristics and then re-synthesizes speech from that representation, often using a different excitation source. Historically, vocoders were developed to compress voice for transmission and storage by separating spectral information from the excitation signal.
A typical channel vocoder uses a bank of bandpass filters to divide the signal into frequency bands,
Homer Dudley at Bell Telephone Laboratories built the first practical vocoder in the 1930s, with devices such
Modern developments encompass several forms: formant vocoders focus on preserving spectral envelope and formant structure; phase
Applications include bandwidth-reducing speech transmission, speech synthesis and TTS, and creative voice transformation in music. Limitations