A Fixed Rate Speech Coder with Improved Database Search
Byeong-Gwan Iem · International Journal of Fuzzy Logic and Intelligent Systems · 2017
A fixed rate speech coder having improved database search performance is proposed.In the speech coder, the 10 ms block of speech is band-passed using the filter bank, and the inflection points (IP) for each band are detected and analyzed to get the short-time statistics like the energy and IP rate.The obtained IP statistics are used to decide if the speech block is voiced or unvoiced.Then the encoder searches for the closest IP pattern either at the voiced part or at the unvoiced part of the IP database.For further reduction of the search time, the entries of the database parts corresponding to the neighboring subbands are checked for the obtained IP pattern.As results, about 94.5% decrease in search time is achieved compared to the exhaustive search.With 10 subbands and 240 entries for each band, the reconstructed signal shows about 5.2 dB SNR at 32 kbps data rate.