Similarity Measure Optimization for Target Detection

Today, in the era of data and computing, fast and reliable retrieval of information has become of great importance for security and military applications, and continues to be such, as the amount available digital data increases every second. While the search and retrieval of text data has produced mature products and are today being used in search engines everyday by everyone, the retrieval of spoken content still remains a young research, especially for low resource languages where the available data is scarce to train reliable speech recognition systems. This chapter provides a thorough introduction of a speech retrieval task called “keyword search” and presents a novel similarity measure optimization-based approach. The case study was experimented on telephone conversations in three different languages and thousands of keywords randomly selected from each language were searched in the document. The experiments show that the technique introduced in this chapter offers a new methodology to handle the terms that does not even exist in the vocabulary of the speech recognition systems.