Abstract: In a system for allocating a user identifier to a user of a voice-operated service, the user is requested (20) to utter words in a set of requested words. A speech recognizer (2) compares (24) each received word with a set of speech recognition templates, each template corresponding to the requested words. For each word uttered the speech recognizer generates (26) codes (W1, W2) which are the first and second best matched templates, and further generates (28) scores (D1, D2) indicating the extent of deviation of the received uttered words from the first and second best matched templates. The speech recognizer (2) then computes (32) a reliability criterion for each word by subtracting the scores (D1, D2) and comparing (34) the subtraction result with a threshold. Words having the greatest reliability criterion above the threshold are selected for the user identifier.

Abstract: A speech recognition system comprises a recogniser (2) for receiving speech signals from users. The recogniser (2) compares each received word with templates of words stored in a reference template store (3) and flags each template that corresponds most closely to a received word. The flagged templates are stored in a template store (11). The recogniser (2) compares the speech pattern from a given user of a second utterance of a word for which a flagged template is already stored in the template store (11) with the templates stored in the reference template store (3) and with the flagged templates in the template store (11), so as to produce a second flagged template of that word. The second flagged templates are also stored in the template store (11). Sifting means (21) analyse a group of flagged templates of the same word, and produce therefrom a second, smaller group of templates of the word. These templates are stored in another template store (22).

Abstract: A digital sub-band coder for audio signals provides for adaptive allocation of bits to (e.g.) two sub-bands. Estimation of the relative energy content of the bands is determined by reference only to those bits which are always transmitted, so that decoding can take place without the need for transmission of side information. Accompanying data may be transmitted in a fixed bit position, or may be by insertion of the data into the lower energy band. In the latter case, the data may optionally be duplicated in both bands when their energy contents are random. The invention can be applied to embedded ADPCM coders.

Abstract: A slurry explosive composition comprising inorganic oxidizing salt and a liquid solvent, dispenser or carrier for the salt, which liquid is emulsified with a sensitizing liquid aliphatic mononitrate containing from 3 to 8 carbon atoms per molecule.