Abstract: A speech recognition system comprises a controller application, a speech recogniser, and a modification apparatus disposed between them. The controller application has an output arranged to produce a speech signal, an input arranged to receive a recognised speech result signal and a control command output arranged to produce a command signal. The speech recogniser has a pattern matcher, a speech input arranged to receive the speech signal from the controller application, an output arranged to produce the recognised speech recognised signal and a control command input arranged to receive the command signal. The modification apparatus is disposed between the output of the controller application and the input of the speech recogniser; between the output of the speech recogniser and the input of the controller application; and between the control command output of the controller application and the control command input of the speech recogniser.