The document summarizes several presentations on artificial bandwidth extension techniques for narrowband speech signals. It discusses methods that aim to reproduce voiced sounds using pitch-adaptive modulation, voicing-based codebook vector quantization, and conditional codebooks to handle different speech types. It also describes techniques using speech recognition and original bandwidth extension schemes with high frequency parameter estimation. The results sections indicate that some methods were evaluated through listening tests, CCR tests, ABX tests, and measurements of spectral distortion.
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