TRANSMISSION OF VOCODER SIGNALS OVER SMALL CAPACITY BINARY CHANNELS,
Abstract
With a fixed capacity of a binary channel, reduction of intelligibility of synthesized speech due to lowering the frequency of discretizing within certain limits is compensated for by increasing the number of binary digit bits which represent the levels of the signal peramaters, however, reducing the frequency of discretization to values below 40 Hz led to irreversible losses in speech intelligibility. The introduction of a logarithimic scale of quantification levels of signal peramaters a sub 1 -- a sub 8 while maintaining an assigned fixed speech intelligibility level permits the capacity of a binary channel to be reduced approximately two times in comparison with the capacity required with an equivalent scale of levels (i.e., without using blocks LC and E). With a channel capacity of less than 1,500 bits per second it is more expedient to eliminate signal parameter a sub 8 and thus increase the accuracy of transmitting the remaining signal parameters. The qualitative indexes of the synthesized signal are almost completely maintained when transmitting along a binary channel having a capacity of the order of 2,500 bits per second. The maximally-admissible channel capacity, corresponding to an intelligibility level of sound combinations of 70%, is (without transmitting the base tone) 1,000 bits per second. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1969
- Accession Number
- AD0687895
Entities
People
- V. I. Kulya
Organizations
- United States Army Foreign Science and Technology Center