Low-Bit Rate Speech Encoders Based on Line-Spectrum Frequencies (LSFs)

Transcoding Between Two DoD Narrowband Voice Encoding Algorithms (LPC-10 and MELP)

“…" Line Spectrum Pairs for MELP: LSPs are frequency domain parameters, and an error in an LSP only affects the speech spectrum near that frequency [6]. Since LSP errors are frequency selective, they can be quantized efficiently by exploiting the human perception characteristics.…”

High-Quality 800-b/s Voice Processing Algorithm.

“…A similar template collection approach has been used in our previous 800-b/s voice processor that achieved a DRT score of 87 [9]. Likewise a similar approach was also successfully used by Gold [161 for the channel vocoder, and Paul 1171 for the spectral-envelope-estimation vocoder.…”

“…We have presented various aspects of LSPs in an NRL report [9]. In this section we present essential aspects of LSPs beneficial to low-bit-rate speech encoding.…”

“…Real-root removed sum and difference filters are obtained from P(z) 0 (i z')PP(z) (8) and Q(-) -(I -z')QQ(z). (9) The coefficients for PP(z) and QQ(z) are obtained by polynomial division. Table 2 lists the results.…”

Unlimited Vocabulary Synthesis Using Line Spectrum Pairs

“…LSP parameters are derived from LPC prediction coefficients through the decomposition of the impulse response of the LPC analysis filter into a pair of even and odd functions, each having roots along the unit circle of the complex z plane [2][3][4]. LSP prameters are naturally ordered and Manuscript approved April 16.…”