Patent ID: 7970610

Claim:
A device for retrieving a data record from a database storing a plurality of data records, each of a plurality of which includes a data item of a first category and a data item of a second or subsequent category, wherein the data items in the first category are designated as being either common or uncommon in dependence upon the frequency with which they appear in the data records stored in the database, the device comprising: audio representation storage storing an audio representation in respect of each of the common data items in the first category but not in respect of the uncommon data items in the first category; association storage storing associations between each of at least some common data items and a plurality of uncommon data items whose audio representations are similar to but different from the audio representation of the respective associated common data item; a comparator which compares a signal derived from an unknown utterance with each of the audio representations of common data items stored in the audio representation storage, generating a measure of similarity at least in respect of one or more audio representations which are sufficiently similar to the compared signal to give rise to a measure of similarity above a predetermined threshold and designating as candidate first category data items both the common data items whose audio representations gave rise to a measure of similarity above the threshold and the uncommon data items associated with the designated common data items according to the association storage means; a selector which selects one or more data items of a second or subsequent category; and a data retriever which retrieves one or more data records including a first category data item equal to one of the candidate first data items designated by the comparator and a second or subsequent category data item selected by the selector.