Abstract: The present invention relates to a user interactive user friendly speech recognition controller and method of operating the same. The speech recognition controller recognises (S1, S11, S12, S20, S27) at least one keyword in a speech utterance enunciated by a user and obtain (S2, S7, S13, S24, S40) for said at least one recognized keyword a recognition reliability which indicates how reliably said at least one keyword has been recognized correctly by the speech recognition controller. It then compares (S3, S26, S41) said reliability with a recognition reliability threshold and if said obtained reliability is lower than said recognition reliability threshold, it provides (S4, S14, S32, S35) an unreliability indication to the user (S4, S14, S32). In response to said unreliability indication it recognises at least one further keyword and then corrects said at least one recognized recognized in response to said unreliability indication to the user.

Abstract: Echo cancellation in a full duplex loudspeaking telephone is usually effected by means of an adaptive filter, which by means of a combining (difference) circuit cancels the microphone-signal component picked up by the microphone via the acoustic echo path. For a correct operation of the adaptive filter the levels between the signals at the input line and at the input of the combining circuit should be in a given ratio. For automatically adjusting this ratio an attenuator circuit (26) is arranged before the combining circuit, and at the output of the combining circuit an amplifier (22) is added whose gain is inverse to the attenuation of the attenuator circuit. A control circuit (40) compares the levels of the signals at the input line (10) and at the input of the combining circuit and adjusts the attenuation of the attenuator circuit and the gain of the amplifier accordingly.

Abstract: The invention relates to an echo canceller (1, 2, 3, 6) including an adaptive filter (3) which can be inserted between a receive path (r) and a send path (s), and including a non-linear filter (2) which can be inserted in the send path (s). The echo canceller is to have an improved echo cancellation, especially when the state of doubletalk occurs, thus substantially avoiding an erroneous activation of the non-linear filter when the state of doubletalk is detected. For this purpose, it is proposed that the echo canceller (1, 2, 3, 6) comprises an up/down counter (11) provided for counting up with a first value (Z.sub.U) when the state of doubletalk (d) occurs and for counting down with a second value (Z.sub.D) smaller than the first value (Z.sub.U) when the states of non-doubletalk (a, b, c) occur, the non-linear filter (2) being provided to be inserted in the send path (s) only when the state of far-end speech (c) occurs and when the up/down counter (11) reaches a predeterminable small value (Z.sub.