7. A system for generating a large-scale database of heterogeneous speech, comprising: a processor; a memory, the memory containing instructions that, when executed by the processor, configure the system to: transcribe a plurality of multimedia signals retrieved from a large text database and a speech database; randomly select a plurality of speech segments from the plurality of multimedia signals, wherein each speech segment of the plurality of speech segments is of a random length; generate a plurality of signatures based on the plurality of speech segments; and populate the large-scale database with the plurality of signatures respective of the plurality of multimedia signals.
7. A system for generating a large-scale database of heterogeneous speech, comprising: a processor; a memory, the memory containing instructions that, when executed by the processor, configure the system to: transcribe a plurality of multimedia signals retrieved from a large text database and a speech database; randomly select a plurality of speech segments from the plurality of multimedia signals, wherein each speech segment of the plurality of speech segments is of a random length; generate a plurality of signatures based on the plurality of speech segments; and populate the large-scale database with the plurality of signatures respective of the plurality of multimedia signals. 10. The system of claim 7 , wherein the system is further configured to: determine, for each multimedia signal of the plurality of multimedia signals, if the multimedia signal matches at least one class of multimedia signals based on the plurality of signatures and a set of representative signatures of the class of multimedia signals; and upon determining that at least one multimedia signal of the plurality of multimedia signals does not match at least one class of multimedia signals, create a new class of multimedia signals, wherein the new class of multimedia signals comprises the plurality of signatures as new representative signatures of the new class of multimedia signals.