🚀 go-pugleaf

Since many people had asked about low rate speech vocoding and Sinusoudal
coding references, I thought I'd post them.

Sinusoidal Coding:
This method gives very good quality speech and is also quite robust, working
well under high background noise or music.  Robert J. McAulay and Thomas F.
Quatieri can be contacted at: Speech Systems Technology Group, MIT Lincoln Lab,
244 Wood Street, Lexington, MA  02172 (617)981-7240.

(1) R. J. McAulay and T.F. Quatieri, "Speech Processing Based on a Sinusoidal
Model," The Lincoln Laboratory Journal, Fall 1988, V. 1, N. 2.
(2) R. J. McAulay and T. F. Quatieri, "Speech Analysis/ Synthesis Based on a
Sinusoidal Representation," IEEE Trans. Acoust. Speech Signal Process. ASSP-34,
744 (1986)
(3) R. J. McAulay and T. F. Quatieri, "Multirate Sinusoidal Transform Coding
at Rates from 2.4 kbps to 8.0 kbps, "Int. Conf. on Acoustics, Speech, and
Signal Processing 87 (IEEE, New yuork, 1987), p 1645.
(4) T. F. Quatieri and R. J. McAulay, "Sinewave-based Phase Dispersion for
Audio Preprocessing, "Int Conf. on Acoustics, Speech, and Signal Processing 88
(IEEE New York, 1988) p 2558.

300 BPS LPC-Segment Vocoder:
This algorithm has plenty of areas left for improvement.  It requires a good
deal of hardware, both speed and memory for implementation, but I beleive that
off the shelf DSP plug-in boards with lots of memory may soon make this 
implementable without quite as much time and cost.  Chunks of speech spectra
from a codebook are matched to incoming speech and the index (plus a couple 
other parameters) are transmitted.  Work on codebook design, possibly 
different weightings when calculating euclidian distance, and codebook size 
reduction are just a few of the many areas that could be investigated to 
improve quality.  This algorithm was developed by BBN, and a Real time 
implentation was made by Dr. Edward Hofstadter at MIT Lincoln Lab., who can 
be reached at the same address above.  William Russell at BBN helped consult
with the real-time implementation.

(1) S. Roucos, A. Wilgus, and William Russell, "A Segment Vocoder Algorithm
for Real-Time Implementation," ICASSP '87 (IEEE New York, 1987) p. 1949

			  Thomas E. Jones
			- tj@xn.ll.mit.edu
-- 
tj@xn.ll.mit.edu or tj@ll-xn.arpa          (one of these should work)
Thomas E. Jones, home (617) 924-8326 work (617) 981-5093