As vehicle location tracking and communication systems increase in functionality and complexity, generate synthesized voice messages, and employ speech recognition to accept spoken command inputs, it is clear that safe and effective use of the system requires integration of the entire truck cab audio environment. Accordingly, in one or more embodiments the present invention relates to a priority-based audio integrator that controls the routing of audio signals from a plurality of audio sources to one or more speakers. In particular, audio from a newly active high-priority audio source may interrupt currently-playing audio from a low-priority audio source in an elegant manner, and with a unique audible indicator, to efficiently deliver audio from competing sources to the driver of a vehicle in a way that maximizes the driver's ability to comprehend and interpret all audio. Voice communication audio may be buffered during the switch-over, to avoid the loss of audible information. Although the present invention is described herein in the context of a truck cab, it is not limited to this application, and may be advantageously applied to control audio sources in any vehicle.
The audio output of each audio source 12-22 is provided as an input to an active audio detection circuit 24. The active audio detection circuit 24 determines which of the audio sources 12-22 are active. In one embodiment, the active audio detection circuit 24 monitors each audio signal, and outputs an indication of active audio when the signal energy exceeds a predetermined threshold. In another embodiment, an audio source 12-22 may provide both an audio signal and an audio active signal (e.g., a sideband signal) to the active audio detection circuit 24. In still another embodiment, an audio source 12-22 may output digital audio, or a combination of digital and analog audio, with the audio active condition being indicated by digital content (e.g., the data in control channels, packet headers, or the like). Those of skill in the art will recognize that the active audio detection circuit 24 may include any combination of the above active audio detection techniques.
The active audio detection circuit 24 sends an indication of which audio sources 12-22 are active to a controller 26. The controller 26 may comprise a general-purpose microprocessor, microcontroller, Digital Signal Processor (DSP), or other processor, with its functionality defined by software, as known in the art. Alternatively, the controller 26 may comprise a dedicated state machine or other hard-wired, special-purpose circuit. In either case, the controller 26 may be implemented as a stand-alone integrated circuit, ASIC, FPGA, or the like, or may comprise a processing core implemented along with other circuit elements in an ASIC or full-custom integrated circuit.
The controller 26 prioritizes the audio sources 12-22, and monitors the indication from the active audio detection circuit 24 of which of the audio sources 12-22 are currently active. In one embodiment, communication-related audio sources, such as the CB radio 14 and cell phone interface 22, are assigned a higher priority than entertainment-related audio sources, such as radio receivers 16, 18, MP3 player 20, or the like. In one embodiment, information-related audio sources, such as the vehicle navigation/communication system 12, are additionally assigned a higher priority than the entertainment-related audio sources 16, 18, 20. In one embodiment, the relative priority between communication and information audio sources may be selected by the user. All of the relative priorities of audio sources 12-22 are preferably configurable, such as by software. In one embodiment, the priority of audio sources 12-22 is determined by which audio input jack of the audio integrator 10 each audio source 12-20 is plugged into.
In one embodiment, the priority of one or more audio sources 12-22 may change dynamically. For example, a vehicle navigation/communication system 12 may issue pre-recorded or synthesized voice prompts, or turn-by-turn directions, to direct the driver along a predetermined course. A preliminary warning (e.g., “exit 1 mile ahead”) may have a relatively low priority, and may not interrupt, for example, incoming audio from the CB radio 14. As the vehicle navigation system tracks the progress of the vehicle, an updated warning (e.g., “exit 500 feet ahead”) may have a much higher priority, and would interrupt CB radio 14 audio output. As another example, a message received by the vehicle navigation/communication system 12 may be flagged as a high-priority message, and the controller 26 may assign a corresponding high priority to a synthesized voice audio rendition of the message.
An audio multiplexer 28 receives the audio output of each audio source 12-22 and, in response to the controller 26, passes audio from one of the audio sources 12-22 to an audio amplifier 30. The audio amplifier 30 adjusts the amplitude of the audio signal it received from the audio multiplexer 28 in response to the controller 26 via, e.g., an adjustable preamp, a gain control circuit, or the like. The amplified audio output of the audio amplifier 30 is received by one or more speakers 32, which transduce the audio signal into audible sound, as well known in the art.
The controller 26 operates to interrupt a currently-playing audio source 12-22 wherein a higher-priority audio source 12-22 becomes active. For example, audio from a radio 18 or MP3 player 20 may be interrupted when audio from a communication audio source such as a CB radio 14 or navigation system 12 becomes active. When the communication audio source again becomes inactive (i.e., the message has been received), the controller 26 will return to playing the previously-active audio source 12-22, if no intervening, a higher-priority audio source 12-22 has become active. That is, upon the highest-priority (and hence, the currently-playing) audio source 12-22 becoming inactive, the next-highest-priority active audio source 12-22 will be played. If two or more active audio sources 12-22 have been assigned the same priority, the one that was previously interrupted by a higher-priority audio source 12-22 will be selected when the higher-priority audio (and any intervening higher-priority audio) goes inactive.
In one embodiment, when switching between audio sources 12-22—for example, when switching from a CD player 18 to a satellite radio receiver 16—the controller 26 gradually decreases or “ramps down” the volume level of the currently-playing CD player 18, by sending appropriate control signals to the audio amplifier 30 to decrease the output audio amplitude, prior to directing the audio multiplexer 28 to route the selected satellite radio receiver 16 to the audio amplifier 30. This feature is particularly useful in the case where a higher priority audio source becomes active—such as a communication being received on the CB radio 14. A sudden or immediate transition of audio from music to a CB message may startle the driver. In contrast, ramping down the volume of the currently-playing, lower-priority audio source alerts the driver that a higher-priority audio is upcoming.
In one embodiment, when switching from a first audio source to a second audio source, the controller 26 directs a tone generator unit 33 to generate unique audible indicator, such as a tone or chime. The controller 26 routes the unique audible indicator to the speakers 32, prior to routing audio from the second audio source to the speakers 32. A separate audible indicator is uniquely associated with each audio source 12-22, and playing the audible indicator serves as a “flag” or indication to the user of which audio source 12-22 is about to be played. This is particularly useful in the case of a higher-priority audio source that becomes active, interrupting a lower-priority audio source that is currently playing, as described above. By playing a tone uniquely associated with the higher-priority audio source, the driver is alerted as to the nature of the upcoming audio (e.g. conversation from a CB radio 14, or turn directions from the vehicle navigation system 12). Research indicates that drivers are better able to interpret voice audio when they anticipate its nature.
Some of the audio sources 12-22 generate high-priority, voice communication audio, such as the CB radio 14 or hands-free cell phone interface 22 (as opposed to, e.g., voice on a radio station or book-on-tape). Another source of high-priority, voice communication audio may be pre-recorded or synthesized voice audio from the vehicle navigation/communication system 12. For example, the navigation system may issue turn-by-turn directions, or the communication system may “read” e-mail or other messages to the driver. If any of these high-priority audio sources become active when a lower-priority audio signal is being routed to the speakers 32, the beginning of the voice communication message may be lost during the time required for the audio multiplexer 28 to switch to the new audio source. This is particularly true when the currently-playing audio is faded out prior to the switch, and when a unique tone identifies the upcoming voice communication audio source.
In one embodiment, the audio integrator 10 includes an input selector 34 and a time delay buffer 36. The input selector 34 selects one of a plurality of high-priority, voice communication audio sources 12, 14, 22 in response to the controller 26, and outputs the selected voice communication audio to the time delay buffer 36. The time delay buffer 36 delays the voice communication audio by at least an amount sufficient to allow a currently-playing, low-priority audio signal to be faded out and a unique, audible identifier to be sounded, prior to routing the output of the time delay buffer 36 to the speakers 32 via the audio multiplexer 28.
In most cases, the time delay buffer 36 is only required to delay voice communication audio by a few seconds—time to ramp down currently-playing audio and sound an audible indicator associated with the delayed voice communication audio. However, in some circumstances, more delay may be required. For example, a relatively low priority navigation prompt may be buffered during a CB radio 14 message. In this case, the time delay buffer 36 must store the longest anticipated navigation prompt, which may comprise, e.g., five to seven seconds of voice communication audio. The depth of the time delay buffer 36 may be optimized for any particular application by those of skill in the art.
Although not depicted in
In one or more embodiments, the audio integrator 10 additionally controls the truck cab audio environment during audio input conditions. In particular, the controller 26 quiets all audio output from the speakers 32 by directing the audio amplifier 32 cut off audio output for the duration of any audio input condition. An audio input condition may be detected by monitoring the Push-To-Talk (PTT) button of, e.g., the CB radio 14 microphone. Additionally, as the vehicle navigation/communication system 10 evolves, it may employ voice recognition capability to accept audible commands from the driver. Accordingly, the vehicle navigation/communication system 12 may include a dedicated microphone with a PTT switch. Alternatively, an integrated system may provide a single microphone with separate PTT switches is for the CB radio 14 and vehicle navigation/communication system 12 functionality. In either case, the actuation of a PTT button indicates an audio input condition, during which the controller 26 will quiet all audio output from the speakers 32. This is necessary to allow clear communication on the CB radio 14, and to maximize the voice recognition effectiveness of the vehicle navigation/communication system 12.
The audio integrator 10 according to this embodiment connects to the same audio sources 14, 16, 18, 20, 22 and truck cab speaker 32 as the audio integrator of the embodiment depicted in
The audio integrator 10 according to this embodiment additionally includes a voice unit 48 that generates a synthesized voice communication audio from the MAS, and recognizes driver commands to the MAS during an audio input condition signified by actuation of the voice command PTT button 13. In addition to synthesizing voice communication audio, the voice unit 48 may additionally generate the unique audible indicators such as chimes, tones, and the like, in lieu of the tone generator unit 33.
The audio integrator 10 according to this embodiment also includes a device control and interface unit 50. In response to the MAS 46, the device unit 50 generates control signals (e.g., channel selection and the like) to control audio devices such as the radio receiver 18 or satellite radio receiver 16. In addition, the device unit 50 may receive traffic and weather data from the satellite radio receiver 16, forwarding this data to the MAS 46 for use by its route planning functionality.
Further integration is anticipated, and is within the scope of the present invention. For example, one or more of the audio sources 14-22, 46 may be fully integrated into the audio integrator 10. In particular, entertainment, communication, and information audio sources 14-22, 46; the audio integrator 10 functionality of controlling the truck cab audio environment; and video displays such as navigation system moving-map displays, back-up and blind-spot camera video display, and entertainment video display such as movies or games (interlocked to the ignition); may be fully integrated into a single, in-dash unit.
When the active audio detector circuit 22 detects an active output of a high-priority audio source 12, 14, 22, 46 (block 56), it sends an indication of such to the controller 26. The controller 26 then routes audio from the active, high-priority audio source 12, 14, 22, 46 to the time delay buffer 36 via control of the time delay buffer input selector 34, and controls the time delay buffer 36 to buffer the high priority audio (block 58). Simultaneously, the controller 26 ramps down the correctly-playing, low priority audio volume by controlling the audio amplifier 30 to reduce the amplitude of its audio output (block 60). The controller 26 then routes a unique audible indicator associated with the high-priority audio source from the tone generator unit 33 to the speakers 32 (block 62). The controller 36 then routes the buffered high-priority audio from the time delay buffer 36 to the speakers 32 (block 64).
In this manner, the driver does not miss any of the high-priority audio, due to the time delay buffering. The driver is mentally alerted to the fact of an incoming high-priority audio message by the ramp-down in volume of the currently-playing audio. The driver is further mentally alerted to the nature of the upcoming high-priority audio message by the unique audible indicator. Research has shown that the drivers receive and comprehend disparate audio messages more effectively when they are presented in an orderly, identified fashioned, as opposed to the cacophony of independent, autonomous audio sources.
Although various embodiments of the present invention has been described herein with respect to the cab of a class 8 truck, the present invention is not limited to this application. As those of skill in the art will readily recognize, the teachings of the present disclosure may be advantageously applied to control the audio environment of any vehicle, such as an automobile, aircraft, or the like. Furthermore, although the present invention has been described herein with respect to particular features, aspects and embodiments thereof, it will be apparent that numerous variations, modifications, and other embodiments are possible within the broad scope of the present invention, and accordingly, all variations, modifications and embodiments are to be regarded as being within the scope of the invention. The present embodiments are therefore to be construed in all aspects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.