Method and system for preselection of suitable units for concatenative speech
View Patent ↗A system and method for improving the response time of text-to-speech synthesis utilizes “triphone contexts” (i.e., triplets comprising a central phoneme and its immediate context) as the basic unit, instead of performing phoneme-by-phoneme synthesis. The method comprises a method of generating a triphone preselection cost database for use in speech synthesis, the method comprising 1) selecting a triphone sequence u 1 -u 2 -u 3 , 2) calculating a preselection cost for each 5-phoneme sequence u a -u 1 -u 2 -u 3 -u b , where u 2 is allowed to match any identically labeled phoneme in a database and the units u a and u b vary over the entire phoneme universe and 3) storing a group of the selected triphone sequences exhibiting the lowest costs in a triphone preselection cost database.
1. A computing device that generates a database for use in speech synthesis, the computing device generating the database according to a method comprising:
selecting a triphone sequence;
calculating a preselection cost for each 5-phoneme sequence where a unit of the 5-phoneme sequence is allowed to match any identically labeled phoneme in a database and at least two units of the 5-phoneme sequence vary over the entire phoneme universe; and
storing a group of the selected triphone sequences exhibiting the lowest costs in a triphone preselection cost database by:
determining a plurality of N least cost database units for the particular 5-phoneme context;
performing the union of the N least cost units for all combinations of the at least two units;
storing the union created in the step of performing the union in the triphone preselection cost database; and
repeating steps of selecting, calculating and storing a group of the selected triphone sequences for each possible triphone sequence.
2. The computing device of claim 1 , wherein the triphone sequence comprises u 1 -u 2 -u 3 and the 5-phoneme sequence comprises u a -u 1 -u 2 -u 3 -u b , where u 2 is allowed to match any identically labeled phoneme in a database and the at least two units comprise u a and u b vary over the entire phoneme universe.
3. The computing device of claim 1 , wherein the method for generating the database further comprises generating a key to index each triphone in the database.
4. The computing device of claim 1 , wherein a plurality of fifty least costs sequences for any possible 5-phone context are stored.
5. The computing device of claim 1 wherein the preselection cost is the target cost or an element of the target cost.
6. A method for generating a triphone preselection cost database for use in speech synthesis, the method comprising, for each of plurality of triphone sequences:
calculating a preselection cost for each 5-phoneme sequence, wherein a triphone sequence of the plurality of triphone sequences is included in each 5-phoneme sequence;
storing a group of triphone sequences exhibiting the lowest costs in a triphone preselection cost database by:
a) determining a plurality of N least cost database units for the particular 5-phoneme context:
b) performing the union of the N least cost units for all combinations of two selected units from the 5-phoneme sequence; and
c) storing the union created in step b) in the triphone preselection cost database.
7. The method of claim 6 , wherein the selected triphone sequence comprises u 1 -u 2 -u 3 and the 5-phoneme sequence comprises u a -u 1 -u 2 -u 3 -u b , where u 2 is allowed to match any identically labeled phoneme in a database and the units u a and u b vary over the entire phoneme universe, and wherein the two selected units from the 5-phoneme sequence for which the union is performed are u a and u b .
8. The method of claim 6 , further comprising generating a key to index each triphone in the triphone cost selection database.
9. The method of claim 6 , wherein a plurality of fifty least costs sequences for any possible 5-phoneme context are stored.
10. The method of claim 6 , wherein the preselection cost is a target cost or an element of the target cost.
11. A computer-readable medium storing instructions for controlling a computing device to generate a triphone preselection cost database for use in speech synthesis, the instructions comprising, for each of plurality of triphone sequences:
calculating a preselection cost for each 5-phoneme sequence, wherein a triphone sequence of the plurality of triphone sequences is included in each 5-phoneme sequence;
storing a group of triphone sequences exhibiting the lowest costs in a triphone preselection cost database by:
a) determining a plurality of N least cost database units for the particular 5-phoneme context;
b) performing the union of the N least cost units for all combinations of two selected units from the 5-phoneme sequence; and
c) storing the union created in step b) in the triphone preselection cost database.
12. The computer-readable medium of claim 11 , wherein the selected triphone sequence comprises u 1 -u 2 -u 3 and the 5-phoneme sequence comprises u a -u 1 -u 2 -u 3 -u b , where u 2 is allowed to match any identically labeled phoneme in a database and the units u a and u b vary over the entire phoneme universe, and wherein the two selected units from the 5-phoneme sequence for which the union is performed are u a and u b .
13. The computer-readable medium of claim 11 , further comprising generating a key to index each triphone in the triphone cost selection database.
14. The computer-readable medium of claim 11 , wherein a plurality of fifty least costs sequences for any possible 5-phoneme context are stored.
15. The computer-readable medium of claim 11 , wherein the preselection cost is a target cost or an element of the target cost.