5. The method of claim 1 , wherein the step of carrying out at least one iteration of the reducing and re-attempting steps further comprises: announcing a noise reduction advisory message to a user responsive to the received noise error; and receiving a second noise error from the speech recognition unit responsive to a repeated user voice command, wherein the repeated user voice command is received following the noise reduction advisory message, and wherein the reducing a confidence threshold for an appropriate grammar set is responsive to the received second noise error.
7. The method of claim 5 , wherein the step of carrying out at least one iteration of the reducing and re-attempting steps further comprises: storing the repeated user voice command in the telematics unit; and attempting to recognize the stored repeated user voice command at the speech recognition unit after the confidence threshold is reduced.