Google is trying out a new audio indexing service for its search engine.

Google Audio Indexing will allow users to search through political speeches, particularly those by US presidential candidates Barack Obama and John McCain, for the use of certain words.

Results for the searches are then returned as video clips from the speeches.

The company said that the new system is based on an application developed as an add-on for iGoogle.

Designed to track the use of certain buzz words in speeches by presidential candidates, the application was soon put to other uses by users.

After seeing the reaction to the service, Google decided to expand the audio indexing system to include speeches from other politicians and turn the iGoogle application into a standalone web service.

Google Audio Indexing will also add features such as the ability to search within a specific video and to share results with other users.

The new service is currently being offered through the Google Labs site as a beta trial.