Electrical audio signal processing systems and devices – Binaural and stereophonic – Hearing aid
Patent
1984-11-16
1990-01-23
Harkcom, Gary V.
Electrical audio signal processing systems and devices
Binaural and stereophonic
Hearing aid
H04B 166
Patent
active
048963569
ABSTRACT:
A pair of filters (H.sub.1 H.sub.2) split an input signal into two frequency sub-bands (defined by a transition frequency) which are down-sampled and coded: after sample rate restoration the signals are filtered (K.sub.1 K.sub.2) and combined. To reduce signal delays, the delay response of each filter is non-constant, having a maximum at or beyond the transition frequency. Preferably non-quadrature filter pairs are used. Filters may be cascaded for more than two sub-bands.
REFERENCES:
Crochiere, Weber and Flanagan, "Digital Coding of Speech in Sub-bands", Bell System Technical Journal, vol. 55, pp. 1069-1085, Oct. 1976.
Esteban and Galand, "Application of Quadrature Mirror Filters to Split Band Voice Coding Schemes", IEEE ICASSP, 1977, pp. 191-195.
Crochiere and Penfield, "On the Efficient Design of Bandpass Digital Filter Structures", IEEE Trans. Acoustics, Speech, and Signal Processing, Aug. 1975, pp. 380-381.
Cheung and Winslow, "High Quality 16 kb/s Voice Transmission: The Subband Coder Approach", IEEE ICASSP, 1980, pp. 319-322.
Galand and Esteban, "16 KBPS Real Time QMF Sub-Band Coding Implementation", ICASSP, 1980, pp. 332-325.
Johnston, Crochiere and Goodman, "A Digital Sub-Band Coder for Speech Communication at 9.6 kb/s", 1977 Inter. Conf. on Communications (12-15 Jun. 1977), pp. 193-197.
Article from IEEE Transactions on Acoustics, Speech and Signal Process, vol. 36, No. 9, Sep. 1988, entitled "A New Approach to Recursive Mirror Filters with a Special Application in Subband Coding of Images", pp. 1496-1500.
The Bell System Technical Journal, vol. 60, Sub-Band Coding, by R. E. Crochier, pp. 1633-1653.
Sub-Band Coder Design Using Recursive Quadrature Mirro Filter, by A. Ramstad and Ole Foss, Signal Processing Theories and Applications, pp. 747-752.
"A Class of Infinite-Duration Impulse Response Digital Filters for Sampling Rate Reduction", by Horacio G. Martinez et al, IEEE Transactions on Acoustics, Speech, and Signal Processing, vol. ASSP-27, No. 2, Apr. 1979, pp. 154-162.
British Telecommunications public limited company
Harkcom Gary V.
Merecki John A.
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