EP0469023B2

EP0469023B2 - Sound synthesizer in a vehicle

Info

Publication number: EP0469023B2
Application number: EP90906299A
Authority: EP
Inventors: Anthony Malcolm ''highfields'' Mcdonald; David Charles ''nirvana'' Quinn; David Christopher ''sommerset'' Perry
Original assignee: Group Lotus PLC
Current assignee: Group Lotus PLC
Priority date: 1989-04-20
Filing date: 1990-04-19
Publication date: 1999-12-01
Anticipated expiration: 2010-04-19
Also published as: ES2078341T5; DE69023133T3; JPH04504916A; GB8908980D0; EP0469023B1; WO1990013109A1; ATE129352T1; DE69023133D1; DE69023133T2; JP3261128B2; EP0469023A1; ES2078341T3

Abstract

A noise enhancement system for use in a vehicle comprises a source (15, 20, 22) of signals representing desired sound related to vehicle operation for example the sound of a high power engine being accelerated. In dependence on sensed vehicle operation or experience, the signals are fed, to one or more loudspeakers (11, 26) or vibration actuators (27) so as to create for occupants of the vehicle a desired sound experience. The system can be integrated with one or both of an incar entertainment system and a noise cancellation system.

Description

The invention relates to the treatment of noise in vehicles, in particular road vehicles.
The driver and passengers in the cabins of conventional passenger cars are exposed to a great deal of externally generated noise, due primarily to the vehicle engine. Various proposals hae been made for reduction of such ambient noise but the present invention is concerned with the enhancement of the vehicle noise experienced by the cabin occupants during normal driving conditions.
DE-A-3420463 discloses a sound enhancement system for a vehicle in which an engine speed proportional frequency signal is taken from an ignition coil and fed to a frequency changer which changes the frequency and generates an output which is selectable by a switch to drive a loudspeaker via an adjustable amplifier. The vehicle sound simulated depends on the frequency selected. This system is however limited in that only a single frequency can be generated at a time and complex sound cannot be generated in response to a range of vehicle operating conditions.
The present invention provides a sound enhancement system for use in a vehicle, the system comprising source means adapted to provide first signals related to operation of the vehicle and the engine thereof, and generating means responsive to the operation of the vehicle and the engine thereof to provide output signals for transducer means to generate simulated vehicle operating sound; characterised in that said first signals comprise a signal or signals responsive to vehicle acceleration provided by a transducer which relate to one or both of throttle position signal or gear changes and the first signals comprise a signal or signals provided by one or both of a microphone responsive to engine noise and a vibration sensor responsive to engine-generated vibrations; in that the system includes a source of stored signals representing vehicle operating sound to be simulated related to vehicle operation; and in that said generating means is responsive to said first signals to employ said stored signals to provide said output signals.
The source of stored signals representing vehicle operating sound can be a prerecorded source. The generating means can comprise a synthesizer and said source of stored signals can comprise a micro-processor for controlling said synthesizer, said micro-processor being adapted to employ said stored signals to control said synthesizer in response to said first signals to trigger the generation of said output signals at appropriate times.
The microphone can be located in the vehicle cabin to provide feedback to the microprocessor. The microprocessor controlling the synthesizer can store signals representing a desired sound to which the synthesizer can be arranged to adapt the transducer output.
The sounds heard by the user of a system embodying the invention can represent for example the sounds of a racing car or other high-performance road vehicle. The system can then be such that these sounds are heard by the cabin occupants whilst the vehicle is being driven, so as to enhance the occupants driving experience.
In particular, the sounds of a high powered engine undergoing sharp acceleration can be produced in response to acceleration of a vehicle fitted with the system of the invention in ordinary driving conditions. The system is responsive to gear changes and/or throttle movement.
One or more loudspeakers and/or one or more vibration actuators of the system are typically located in the vehicle cabin but instead or as well one or more loudspeakers or actuators can be positioned in the engine compartment, or on appropriate engine or body parts to effect or to modify vibration thereof, so that the sound from them is heard by the vehicle cabin occupants, and by persons outside the vehicle by the same route as sound from the vehicle engine.
Although the system of the invention can stand alone, it is conveniently integrated wit the in-car-entertainment (I.C.E) systems now typically provided in passenger cars. The vehicle operation related sound can be integrated with entertainment sound and can be produced in alternation with it, either selectively or according to vehicle operation; for example the former may be heard during acceleration only, giving way to entertainment sound once cruising speed has been reached. The system of the invention can also be integrated with an active noise reduction system which can reduce ambient noise by generating within the vehicle cabin sound vibrations of phase and amplitude such as to cancel or reduce unwanted noise.
Noise reduction can thus be operative to prevent interference with the desired sound related to vehicle operation, as well as with entertainment sound, or it may be operative only as long as entertainment sound is being produced or when an integrated system is otherwise out of use.
The invention is further described below, by way of example, with reference to the accompanying drawing in which:
Figure 1 is a block circuit diagram of a combined audio entertainment and noise control or processing system embodying the invention.
The system illustrated in Figure 1 is an integrated system comprising all the components necessary to provide in the cabin of a passenger motor car enhanced vehicle operation noise. Audio entertainment and/or ambient noise reduction can also be provided, as the operator of the system may desire.
The in-car entertainment (I.C.E) components of the system comprise an audio signal source constituted by at least one of a radio tuner 2 connected to an aerial 4, and a deck or decks 5 for playing one or more of compact discs, digitally recorded tapes or cassettes. The outputs from the tuner 2 and deck or decks 5 are fed to a pre-amplifier 6 fitted with conventional control arrangements 7 for signal source selection and for output adjustment, such as volume and bass and treble controls, or graphic equalization, and switching instruments to be described. These I.C.E. components will typically provide signals on a plurality N of output channels and balance and fader controls will then be provided. The pre-amplifier outputs are supplied by way of a mixer 9, preferably a balanced mixer, to power amplifier means 10 which powers one or more loudspeakers 11 operative in the vehicle cabin.
For enhanced vehicle sound production, the system includes a prerecorded sound source 15 which can comprise a deck of one or other of the types of deck mentioned with reference to the deck 5 , but which need not have the usual facility for selective replacement of the signal storage medium. Operation of the source 15 is dependent on a control signal related to vehicle operation, the control signal relating to throttle movement and/or gear changes, derived from a transducer 16 and supplied to the source on line 17, so that the source delivers signals representing the sounds of acceleration of a high powered vehicle, or other such desirable sounds, during acceleration of the vehicle in which the system is installed.
The system includes one or more microphones 20 providing outputs representing actual vehicle engine noise and a signal treatment unit constituted as a synthesizer 24 controlled by a microprocessor 25. Instead of or as well as the microphone or microphones 20, the system can include one or more transducer 22, for example vibration sensors, responsive to engine operation. The input from the or each microphone 20 or transducer 22 is then used to trigger the generation of a desired output from the synthesizer 24. Enhanced engine or vehicle interior noise is provide, dependent on vehicle operation, as indicated by the control signal from the transducer 16.
The outputs of the source 15 and the synthesizer 24 are supplied to the pre-amplifier 6 on line 19 for sound production in the vehicle cabin by way of the amplifier means 10 and the loudspeakers 11. In addition or instead the pre-amplifier output derived from the source 15 or the synthesizer 24 can be used to drive one or more loudspeakers 26 located externally of the vehicle cabin, for example, in or near the engine compartment of the vehicle so as to enhance the sound actually produced by the vehicle engine and/or a vibration actuator 27 operatively related to a vehicle panel 28. The loudspeaker 26 and/or actuator 27 is powered by way of one or more power amplifiers 29.
For noise reduction, the system includes an adaptive noise cancellation controller 30 which may advantageously be of the kind described in WO 88/02912.
The controller 30 provides, on L channels, output signals derived from a reference signal by adaptive filtering carried out by a programmed microprocessor and memory unit in dependence on error signals from one or more microphones 31. The microphone 31 may be inconspicuously located in the cabin and the reference signal may be derived directly from the vehicle engine, as described in WO 88/02912.
The output of the one or more microphones 31, or of one or more similarly located microphones if no noise reduction facilities are provided can be fed back to the microprocessor 25, on line 32, so as to provide adaptive control of the unit, as towards a predetermined enhanced noise signal defined in a memory in the unit or in the microprocessor.
The outputs from the pre-amplifier 6 and the controller 30 are fed to the balanced mixer 9 operative to provide outputs for the power amplifier means 10 combining a desired audio signal fro one or other of te sources 2 and 5 together, with a noise cancelling signal from the controller 30, on which the amplifier control arrangements 7 have no effect.
The system is provided with an on/off switch controlling the power amplifiers 10 and 29 and the mixer 9, and selector switches for selecting any one or more of the enhanced noise facility, the entertainment facility, and the noise reduction facility.
The loudspeakers 11 will conveniently match in number the number of the output channels of the pre-amplifier 6, but there may be M channels between the balanced mixer 9 and the amplifiers 10, where M is equal to or greater than the larger of the N entertainment channels or the L noise reduction channels.
One or more of the sources 5 and 15 and the synthesizer 24 may incorporate a pre-amplifier and the output or outputs can then be supplied to the mixer 9 directly as indicated in the figure by broken lines.

Claims

A sound enhancement system for use in a vehicle, the system comprising source means (16, 17, 20, 22) adapted to provide first signals related to operation of the vehicle and the engine thereof, and generating means (15, 24) responsive to the operation of the vehicle and the engine thereof to provide output signals for transducer means (11, 26, 27) to generate simulated vehicle operating sound; characterised in that said first signals comprise a signal or signals responsive to vehicle acceleration provided by a transducer (16) which relate to one or both of throttle position or gear changes and the first signals comprise a signal or signals provided by one or both of a microphone (20) responsive to engine noise and a vibration sensor (22) responsive to engine-generated vibrations; in that the system includes a source (15, 25) of stored signals representing vehicle operating sound to be simulated related to vehicle operation; and in that said generating means (15, 24) is responsive to said first signals to employ said stored signals to provide said output signals.
A sound enhancement system as claimed in Claim 1 characterised in that said generating means (15, 24, 25) comprises a prerecorded sound source (15).
A sound enhancement system as claimed in Claim 1 characterised in that said generating means (15, 24) comprises a synthesiser (24), and said source (15, 25) of stored signals comprises a microprocessor (25) for controlling said synthesiser (24), said microprocessor (25) being adapted to employ said stored signals to control said synthesiser (24) in response to said first signals to trigger the generation of said output signals at appropriate times.
A sound enhancement system as claimed in any preceding claim characterised in that said transducer means (11, 26, 27) comprises at least one of:

a loudspeaker (26) located in or near the region of an engine of the vehicle,

a loudspeaker (11) located in a cabin of the vehicle, and

an actuator (27) operatively related to a body panel (28) of the vehicle for causing vibration of said body panel (28).
A sound enhancement system as claimed in any preceding claim characterised in that said vehicle includes an in-car entertainment system (4, 2, 5, 6, 7, 10, 11) providing an audio signal source (2, 5), the system including a mixer (9) arranged to mix said output signals and signals from said audio signal source (2, 5) to generate a mix of said simulated vehicle operating sound and sound from said audio signal source (2, 5).
A sound enhancement system as claimed in any preceding claim further characterised by a noise cancellation system (30, 31, 32) including at least one error sensing microphone (31), a noise cancellation controller (30), and means (32) to supply signals output from the or each said error sensing microphone (31) to said noise cancellation controller (30), said noise cancellation controller (30) being adapted to generate noise cancelling signals adaptively in response to the output from the or each said error sensing microphone (31) to reduce undesired noise, the system including a mixer (9) adapted to mix said output signals and said noise cancelling signals to generate said simulated vehicle operating sound.
A sound enhancement system as claimed in Claim 3 characterised by a memory, at least one error sensing microphone (31), and means (32) to supply signals output from the or each said error sensing microphone (31) to said microprocessor (25), said microprocessor (25) being operative to adapt said stored signals in response to signals from the or each said error sensing microphone (31) such that said simulated vehicle operating sound generated by said synthesiser (24) attains a predetermined vehicle operating sound defined in said memory or said microprocessor (25).