kõnekodeerimise

Kõnekodeerimine, also known as speech coding or voice coding, is the process of compressing speech signals for efficient transmission or storage. It involves analyzing the characteristics of human speech and representing it in a digital format using fewer bits than would be required for uncompressed audio. This reduction in data size is crucial for applications like mobile phone communication, voice over IP (VoIP), and audio recording where bandwidth and storage limitations are common.

The core idea behind kõnekodeerimine is to exploit the redundancies and predictable nature of human speech. Unlike general audio compression that aims to preserve all audible sound, speech coders are optimized for the specific properties of human vocalizations. This includes factors like the frequency range, spectral characteristics, and the way humans produce sounds.

There are two main categories of speech coders: waveform coders and vocoders. Waveform coders directly approximate the speech waveform. Examples include Pulse Code Modulation (PCM) and Adaptive Differential Pulse Code Modulation (ADPCM). Vocoders, on the other hand, model the speech production process, separating the excitation source (e.g., voicing or noise) from the vocal tract filter. Linear Predictive Coding (LPC) is a well-known example of a vocoder.

Modern speech coding techniques often employ advanced algorithms such as Code-Excited Linear Prediction (CELP) and its derivatives. These methods achieve very high compression ratios while maintaining acceptable speech quality. The choice of a specific speech coding algorithm depends on the desired trade-off between compression efficiency, computational complexity, and the perceived quality of the reconstructed speech.