1. A speech recognition system for an automotive vehicle for recording or recognizing a spoken instruction received through a microphone and for activating a vehicle actuator in response to a recognized spoken instruction, which comprises: (a) means for detecting whether or not an automotive vehicle engine is operating and outputting one of an engine operating signal and an engine stopped signal; (b) a speech input and voice detection section connected to the microphone for amplifying a spoken instruction signal transduced through the microphone, detecting the start and end of a spoken instruction, and outputting an instruction start command signal and an instruction end command signal, respectively, in response to detection thereof, at least one of the gain factor in said speech input section and the threshold level in said voice detection section being so adjusted that the sensitivity to spoken instructions can be reduced and that the driver must necessarily utter a spoken instruction in a louder voice to reduce the proportion of noise level to spoken instruction signal level, when said engine operation detecting means outputs said engine operating signal; and (c) a voice analysis section connected to said speech input and voice detection section and responsive to instruction start and instruction end command signals for analyzing the spoken instruction signal from said speech input section, comparing the results of analysis with predetermined reference values corresponding to at least one spoken instruction, and activating at least one actuator when the results of analysis match predetermined reference values associated with the actuator.
1. A speech recognition system for an automotive vehicle for recording or recognizing a spoken instruction received through a microphone and for activating a vehicle actuator in response to a recognized spoken instruction, which comprises: (a) means for detecting whether or not an automotive vehicle engine is operating and outputting one of an engine operating signal and an engine stopped signal; (b) a speech input and voice detection section connected to the microphone for amplifying a spoken instruction signal transduced through the microphone, detecting the start and end of a spoken instruction, and outputting an instruction start command signal and an instruction end command signal, respectively, in response to detection thereof, at least one of the gain factor in said speech input section and the threshold level in said voice detection section being so adjusted that the sensitivity to spoken instructions can be reduced and that the driver must necessarily utter a spoken instruction in a louder voice to reduce the proportion of noise level to spoken instruction signal level, when said engine operation detecting means outputs said engine operating signal; and (c) a voice analysis section connected to said speech input and voice detection section and responsive to instruction start and instruction end command signals for analyzing the spoken instruction signal from said speech input section, comparing the results of analysis with predetermined reference values corresponding to at least one spoken instruction, and activating at least one actuator when the results of analysis match predetermined reference values associated with the actuator. 4. A speech recognition system for an automotive vehicle as set forth in claim 1, wherein said engine operation detecting means is a speedometer.