The present invention relates generally to an interior rearview mirror sound processing system and, more particularly, to an interior rearview mirror sound processing system including a microphone for use in receiving an audio signal within a vehicle and a digital sound processing system for providing a vocal signature signal indicative of speech detected by the vehicular microphone with an enhanced vocal content and a reduced ambient noise content.
Many vehicles today use hands-free cellular telephones or other communication devices to avoid problems which may arise when a driver of a vehicle has to hold a telephone while driving the vehicle. These hand-free devices include a microphone to receive an audio signal from within the vehicle. It is known to include directional or polar microphones in these devices, which constrain the area covered by the microphone to an area where voices would typically originate, such as a driver's head area. In certain applications, these microphones are implemented in an interior rearview mirror, such that the microphone is positioned in front of the driver and at approximately the same level as the head of the driver. However, the location of the mirror may be at a distance which is beyond the optimal operative range of the microphone, due to the forward slant of the windshield away from the driver and the location at which the mirror is mounted thereto. Furthermore, rearview mirrors are adjustable to account for different sized drivers, which may result in the microphone being directed away from the head of the driver or other occupants, and thus receiving other noises from within the cabin of the vehicle.
An additional issue with known mirror-mounted microphones (such as interior rearview mirror assemblies with a microphone located within the movable mirror housing and/or the mirror mounting bracket, such as a header mounting bracket) is that typically, audio or communication devices in vehicles are optional. Accordingly, separate mirror housings and wiring bundles or harnesses are required to accommodate the standard mirror and the optional mirror which includes the microphone or other accessories such as a vehicle alarm status indicator. This leads to a proliferation of parts within the vehicle assembly plants, which further results in increased costs to the vehicle.
Many vehicles which offer hands-free communication devices mount the microphones in a headliner console rearward of the windshield and along the ceiling of the interior cabin of the vehicle. By mounting the microphones in the headliner console, the microphones may be in a substantially fixed position and directed toward the driver head area within the vehicle. However, this positions the microphone substantially above the driver where it may not optimally pick up the voice signal of the driver, since the driver's voice is directed generally forwardly while the driver continues to view the roadway, while the microphone is directed generally downwardly from the ceiling. Furthermore, locating the microphones in a headliner console adds to the vehicle costs, due to additional installation processes and more costly parts, such as additional ceiling trim, console components and the like. Also, locating the microphone in a headliner console fails to avoid the requirement of at least two separate headliner consoles to accommodate the optional microphone verses a console without the microphone.
An additional issue with communication devices in vehicles is that when the device is in use, the user may not be certain that the message conveyed is properly received by the other party. This may be especially troublesome when the other party is an automated voice system which responds to a particular voice communication. When a remote receiving system is operating in voice recognition mode, it is particularly important that alphanumeric speech text is accurately received and interpreted by the remote party. Thus, for example, if the vehicle operator says “Call Dan at extension three-five-seven-nine-six”, it is important that the remote party (which often is a computer-based machine voice recognition system that is operating in voice recognition mode) interprets this correctly and initiates the requested call, e.g., to Dan at Ext: 35796. In a vehicle environment, ambient noise from the like of traffic noise, road noise, wind noise, HVAC noise and engine noise can make it difficult for the remote party to voice recognize with clarity and accuracy the message being telecommunicated.
Therefore, there is a need in the art for a microphone which may be mounted generally forwardly of the driver of the vehicle, and fixedly mounted to maintain proper orientation with respect to the driver of the vehicle. There is also a need for a vehicular mirror based sound processing system that reliably and economically receives sound inputs from the vehicle interior cabin while the vehicle is operating, that distinguishes vocal speech input from non-vocal ambient noise, and that provides an output that is characteristic of the true speech input being provided, devoid of any confusing/interfering ambient noise.