WO2017157595A1

WO2017157595A1 - Apparatus and method for noise cancellation

Info

Publication number: WO2017157595A1
Application number: PCT/EP2017/053123
Authority: WO
Inventors: Iain SUFFIELD; Mark Willis; Sean TRUE; Xavier VINAMATA
Original assignee: Jaguar Land Rover Limited
Priority date: 2016-03-17
Filing date: 2017-02-13
Publication date: 2017-09-21
Also published as: GB201604560D0; GB2548389A

Abstract

Embodiments of the present invention provide a noise cancellation system comprising noise cancellation parameter selection means (110) for receiving occupancy data indicative (325) of vehicle occupancy and determining one or more noise cancellation configuration parameters (305) based thereon and noise cancellation means (120) for receiving one or more noise signals (134, 135) and determining at least one noise cancellation signal (151, 152) based on one or more noise signals (134, 135) according to the one or more configuration parameters.

Description

APPARATUS AND METHOD FOR NOISE CANCELLATION

TECHNICAL FIELD

The present disclosure relates to an apparatus and method for noise cancellation.

Aspects of the invention relate to a noise cancellation system, to a method of generating a noise cancellation signal, and to a vehicle comprising a noise cancellation system.

BACKGROUND Noise, especially within a vehicle, is troublesome for occupants of the vehicle. Noise within the vehicle may distract a driver of the vehicle and may be tiring for the occupants of the vehicle, for example. Mechanical measures have been used to reduce noise within vehicles. However such measures are bulky and heavy. The use of active noise cancellation has been suggested. Active noise cancellation involves the generation of a sound wave to cancel a noise sound wave thus making the environment quieter for a listener.

It is an object of embodiments of the invention to at least mitigate one or more of the problems of the prior art. SUMMARY OF THE INVENTION

Aspects and embodiments of the invention provide a noise cancellation system, a method of generating a noise cancellation signal, and a vehicle comprising a noise cancellation system, as claimed in the appended claims.

According to an aspect of the invention, there is provided a noise cancellation system, comprising noise cancellation parameter selection means for receiving occupancy data indicative of vehicle occupancy and determining one or more noise cancellation configuration parameters based thereon. Advantageously, the occupancy data allows for a targeted noise cancellation solution based on vehicle occupancy, thus effectively reducing noise within the vehicle.

According to an aspect of the invention, there is provided noise cancellation means for receiving one or more noise signals and determining at least one noise cancellation signal. The noise signal may be based one on or more configuration parameters. According to an aspect of the invention, there is provided a noise cancellation system, comprising noise cancellation parameter selection means for receiving occupancy data indicative of vehicle occupancy and determining one or more noise cancellation configuration parameters based thereon, and noise cancellation means for receiving one or more noise signals and determining at least one noise cancellation signal based on one or more noise signals according to the one or more configuration parameters.

According to an embodiment of the invention there is provided a system for as described above, wherein said noise cancellation parameter selection means is a noise configuration unit. In some embodiments the noise configuration unit comprises a processing device arranged to receive said data indicative of vehicle occupancy. In some embodiments the noise cancellation means is a noise cancellation unit arranged to receive the one or more noise signals and to determine the at least one noise cancellation signal. In some embodiments the noise configuration unit comprises a processing device arranged to determine the at least one noise cancellation signal according to the at least one noise cancellation signal.

Optionally, the configuration parameters are parameters associated with at least one transfer function for determining the at least one noise cancellation signal, based on the one or more noise signals.

Optionally, the parameters associated with the at least one transfer function are one or more filter coefficients. Optionally, the configuration parameters selectively activate one or more feedback signals output by associated noise error means. In some embodiments the noise error means is a vibro-acoustic device. The vibro-acoustic device may be one of a microphone or an accelerometer. The noise cancellation means may be arranged to determine the at least one noise cancellation signal based on the one or more noise signals and the one or more feedback signals. Advantageously, the selective activation of one or more feedback signals allows for efficient generation of noise cancellation signals based on vehicle occupancy.

The selectively activating may comprise selecting a weighting value associated with the one or more feedback signals. The selecting may be performed by the noise cancellation means based on the configuration parameters. Advantageously, the selection of a weighting value allows for more fine-grained determination of the influence of each feedback signal, improving the effective noise reduction. Optionally, the noise error means is arranged within a respective noise cancellation zone. The noise cancellation means may be arranged to output a plurality of noise cancellation signals, each provided to a respective noise cancellation zone. Advantageously, noise cancellation zones allow for targeted noise cancellation at one or more positions in the vehicle, improving passenger experience.

According to an embodiment of the invention, the noise cancellation means is arranged to selectively output a plurality of noise cancellation signals. The noise cancellation signals may be associated with a plurality of noise cancellation zones according to the configuration parameters. The noise cancellation parameter selection means may be arranged to determine the configuration parameters to select one or more active noise cancellation zones based on the occupancy data. Advantageously, the output of a plurality of noise cancellation signals allows for effective noise reduction for instances of multiple occupancy within the vehicle.

Optionally, the occupancy data is indicative of a number of occupants of the vehicle and/or a seating position of the occupants of the vehicle. According to an embodiment of the invention, the occupancy data is received from an occupancy determining means of the vehicle.

Optionally, the occupancy determining means is a seatbelt monitoring means. Advantageously this allows determination of the number and, in some embodiments, seating position of occupants in a convenient manner.

According to an embodiment of the invention, the transfer function is a speaker transfer function (STF) indicative of a transfer function from one or more audio output devices. According to another aspect of the invention, there is provided a method of generating a noise cancellation signal, comprising receiving occupancy data indicative of a vehicle occupancy. The method may comprise selecting one or more noise cancellation configuration parameters based on the occupancy data, receiving one or more noise signals, and generating a noise cancellation signal based on the one or more noise signals according to the selected one or more configuration parameters. Optionally, the configuration parameters are parameters associated with a transfer function for determining the at least one noise cancellation signal based the one or more noise signals. Optionally, the parameters associated with the function are one or more filter coefficients.

According to an embodiment of the invention, the method comprises selectively activating one or more feedback signals received from one or more associated noise error means, and determining the at least one noise cancellation signal based on the one or more noise signals and the activated one or more feedback signals. In some embodiments each noise error means is a vibro-acoustic device. The vibro-acoustic device may be one of a microphone or an accelerometer.

Optionally, the method comprises selecting a weighting value associated with the one or more feedback signals.

Optionally, each noise error means is arranged within a respective noise cancellation zone and the method comprises outputting a plurality of noise cancellation signals to the respective noise cancellation zones.

According to an embodiment of the invention, the method comprises selectively outputting a plurality of noise cancellation signals associated with a plurality of noise cancellation zones according to the configuration parameters. The method may comprise determining the configuration parameters to select one or more active noise cancellation zones based on the occupancy data.

Optionally, the occupancy data of the method is indicative of a number of occupants of a vehicle. Optionally, the occupancy data of the method is indicative of a seating position of the occupants of the vehicle.

Optionally, the occupancy data of the method is received from an occupancy determining means of a vehicle. Optionally, the occupancy determining means is one of a seatbelt monitoring means, weight determining means, optical means or a personal communication means; optionally the personal communication means is a mobile phone.

According to an aspect of the invention, there is provided a vehicle comprising a noise cancellation system according to an aspect of the invention.

According to an aspect of the invention, there is provided computer software which, when executed by a computer, is arranged to perform a method according to an aspect of the invention. Optionally, the computer software may be stored on a computer readable medium. The software may be tangibly stored on the computer readable medium.

Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a system according to an embodiment of the invention;

Figure 2 shows a system according to an embodiment of the invention arranged in use in a vehicle;

Figure 3 schematically illustrates a system according to an embodiment of the invention; and Figure 4 shows a method according to an embodiment of the invention.

DETAILED DESCRIPTION Figure 1 illustrates a noise cancellation system 100 according to an embodiment of the invention. The system 100 comprises noise cancellation means 120 and noise cancellation parameter selection means 1 10. The noise cancellation parameter selection means 1 10 is arranged to select one or more configuration parameters of the noise cancellation means 120 based an indication of vehicle occupancy, as will be explained. In use, the noise cancellation parameter selection means 1 10 is arranged to determine vehicle occupancy and to select at least some configuration parameters of the noise cancellation means 120 accordingly in order to improve noise cancellation. In some embodiments the one or more configuration parameters are associated with at least one transfer function associated with the noise cancellation system. In some embodiments, feedback is selectively enabled according to the vehicle occupancy. The selectively enabling may be achieved by adjusting a weight associated with a feedback signal according to the vehicle occupancy.

The noise cancellation parameter selection means 1 10 may be provided in the form of a processor which operatively executes software instructions to determine the one or more configuration parameters of the noise cancellation means 120. Hereinafter the noise cancellation parameter selection means 1 10 will be referred to as a noise configuration unit 1 10. Similarly, the noise cancellation means 120 may comprise one or more processing devices which are arranged, in use, to determine at least one noise cancellation signal 151 , 152 for reducing noise and to provide the noise cancellation signal 151 , 152 to one or more audio output means 141 , 142, as will be explained. The audio output means 141 , 142 may be one or more acoustic devices, such as speakers 141 , 142. The at least one noise cancellation signal 151 , 152 may be determined based upon an input 134, 135 from one or more noise input means 131 , 132. The input 134, 135 from each noise input means may be referred to as a noise signal. The one or more noise input means 131 , 132 may be one or more acoustic sensing devices or vibro-acoustic devices such as microphones or accelerometers 131 , 132. Hereinafter the noise cancellation means 120 will be referred to as a noise cancellation unit 120. The noise cancellation system 100 may be used within a vehicle, such as a land-going vehicle, although it will be realise that other sorts of vehicle are envisaged, such as aircraft and water-borne vehicles. Thus embodiments of the invention relate to in-vehicle noise cancellation i.e. reducing noise within the vehicle by outputting audio corresponding to the at least one noise cancellation signal within the vehicle.

Noise is a significant issue within vehicles. A noisy environment with the vehicle is detrimental to occupant(s) of the vehicle, such as to enjoyment and comfort of the occupant(s). For example, the occupant(s) of the vehicle may become tired through exposure to noise within the vehicle. Furthermore, a characteristic of a premium vehicle is that an environment within the vehicle is relatively quiet. Noise cancellation may be used to reduce the noise experienced by one or more occupants within the vehicle. However it has been noted that the noise cancellation may not be effective across a wide operating range of the vehicle. The noise cancellation system 100 may be arranged to selectively reduce noise arising from one or more predetermined sources such as, although not exclusively, road noise, wind noise, engine noise etc. The noise cancellation system 100 is arranged to adapt to one or more operating conditions of the vehicle and, in particular, occupancy of the vehicle. The occupancy of the vehicle comprises one or both of a number of occupants of the vehicle and a seating position of those occupants within the vehicle.

The noise cancellation unit 120 is arranged to reduce noise within one or more noise cancellations zones within the vehicle. In one embodiment, substantially the entire interior of the vehicle is determined as the noise cancellation zone 10. That is, there may be only one noise cancellation zone within the vehicle, although that cancellation zone may not occupy the entirety of the vehicle interior. However, in some embodiments, each of one or more noise cancellation zones 10, 20 are arranged proximal to an expected location of an occupant of the vehicle. For example, a first noise cancellation zone 10 may be arranged proximal to an intended location of a driver of the vehicle. The intended location may correspond to a head location of the occupant. A second 20, and possibly further, noise cancellation zone(s) may be respectively arranged in relation to each potential further occupant within the vehicle and, in some embodiments corresponding to an expected head location of each occupant. For example, the second noise 20 cancellation zone may be arranged proximal to an intended head location of a front passenger of the vehicle. It can be appreciated that, especially for shorter wavelengths of noise such as noise above 100Hz, or around 300Hz (it will be appreciated that these figures are merely illustrative), the presence of persons within the vehicle and in some cases a position, such as a seating position, of those occupants may influence the effectiveness of noise cancellation within the vehicle. For example, if the speaker 141 is caused, in use, to output the noise cancellation signal 151 its effectiveness particularly in noise cancellation zone 10 but also in cancellation zone 20 may vary depending on the presence of occupants of the vehicle, especially for shorter wavelength audio signals. The noise cancellation system 100 illustrated in Figure 1 is connected, in use, to a first noise input means 131 a second noise input means 132. It will be appreciated that the system 100 may be connected to other noise input means. As noted above, each noise input means 131 , 132 comprises at least one acoustic sensing device. The noise input means 131 , 132 may be an accelerometer 131 , 132. The accelerometer is 131 , 132 is arranged upon a component of a vehicle to determine and output data indicative of structural vibration of a portion of the vehicle in use. In one embodiment the accelerometer 131 , 132 is arranged upon a suspension component of the vehicle, such as a wheel hub carrier of the vehicle, although it will be realised that the accelerometer 131 , 132 may be mounted elsewhere about the vehicle and, in particular, the suspension thereof. Each accelerometer 131 , 132 is arranged to, in use, output a noise signal 134, 135 indicative of vibration applied thereto and, hence, noise caused within the vehicle. The signal 135 is received by the noise cancellation system 100. As will be appreciated, with the accelerometer 131 mounted about the suspension of the vehicle, vibrations applied thereto are characteristic, at least, of a road surface being travelled upon by the vehicle and may also be characteristic of a speed of travel of the vehicle on the road surface. As noted above, it will also be appreciated that the noise input means 131 , 132 may comprise other devices for outputting a noise signal 134, 135 such as a microphone. Each noise signal 134, 135 is indicative of vibrations causing noise within the vehicle determined at a location of the noise input means 131 , 132.

The noise cancellation system 100 illustrated in Figure 1 is further connected, in use a first audio output means 141 associated with the first noise cancellation zone 10 and second audio output means 142 associated with the second noise cancellation zone 20. It will be realised, however, that this is not limiting and that the system 100 may be connected to more than one audio output 141 means per noise cancellation zone 10, 20 and more than two audio output means in total, respectively. It will also be appreciated that it is not necessary for the number of input means 131 , 132 to equal the number of output means 141 , 142.

The noise cancellation system 100 is arranged to output a first noise cancellation signal 151 to the first audio output means 141 , wherein the audio output means 141 in dependence thereon outputs a corresponding audible signal. Similarly, the noise cancellation system 100 is arranged to output a second noise cancellation signal 152 to the second audio output means 142. Each audio output means 141 , 142 is, in one embodiment, an audio output device such as a speaker arranged within an occupant compartment of the vehicle i.e. within an interior of the vehicle for outputting audio corresponding to the respective noise cancellation signal into the occupant compartment of the vehicle. The speaker 141 , 142 may be arranged within, for example, a dashboard, interior body panel or door panel of the vehicle, although it will be realised that these embodiments are not exhaustive. In one embodiment the speaker 141 , 142 is arranged within a headrest of the vehicle proximal to an occupant's expected head position. As noted above, each speaker 141 , 142 may be located within a respective noise cancellation zone 10, 20 indicated with dotted lines in Figure 1 .

As illustrated in Figure 1 the noise cancellation system 100 forms an open-loop system. One or more input noise signals 134, 135 are used to generate one or more noise cancellation signals 151 , 152. However, in some embodiments a closed-loop system is formed by the inclusion of one or more noise error means 161 , 162. Each noise error means 161 , 162 provides a respective feedback signal 171 , 172 to the noise cancellation system 100. The feedback signal 171 , 172 is indicative of noise at a location of the noise error means. In the embodiment illustrated in Figure 1 each noise error means is associated with a respective noise cancellation zone 10, 20 and therefore the feedback signal is indicative of noise within the noise cancellation zone 10, 20. The feedback signal 171 , 172 may be an error signal indicative of remaining noise present within the respective noise cancellation zone 10, 20. The error signal may correspond to a sum of the noise within the noise cancellation zone 10, 20, the audible signal corresponding to the one or more noise cancellation signals 151 , 152 and, in some circumstances, an intended audio signal within the noise cancellation zone such as audio output by an entertainment system of the vehicle such as music representing a desired audio signal. The error signal corresponds to a sum of the noise within the noise cancellation zone 10, 20 and the audible signal corresponding to the respective noise cancellation signal 151 , 152 and may also incorporate the desired audio signal. Thus the desired audio within the noise cancellation zone may be non-zero. The noise error means 161 , 162 may be at least one microphone 161 , 162 arranged within the noise cancellation zone 10, 20. For example, in one embodiment, the noise error means 161 , 162 may be a microphone arranged within the occupant compartment of the vehicle. The microphone 161 , 162 may be arranged within a headrest of the vehicle.

Whilst Figure 1 has illustrated the system 100 comprising one audio output means 141 , 142 and one noise error means 161 , 162 associated with each noise cancellation zone 10, it will be realised that this is not limiting. The system 100 may comprise a plurality of audio output means 141 , 142 and/or a plurality of noise error means associated with each noise cancellation zone 10, 20 and the number of audio output means does not have to equal the number of noise error means.

Figure 2 schematically illustrates a vehicle 200 according to an embodiment of the invention. The vehicle 200 comprises a noise cancellation system according to an embodiment of the invention such as the system 100 illustrated in Figure 1 . The vehicle 200 shown in Figure 2 is illustrated in top-down view showing a cut through of an interior compartment 205 of the vehicle 200. As shown in Figure 2, the interior compartment 205 of the vehicle 200 comprises a plurality of seating positions 210-270 available to occupants of the vehicle 200. A first seating position 210 is associated with a driver of the vehicle, the illustrated vehicle 200 being a land-going or wheeled vehicle. In some embodiments, it may be assumed by the system 100 that the first seating position 210 is always occupied for the purpose of determining a configuration of the noise cancellation system 100. The vehicle 200 further comprises a second seating position 220 which may be associated with a front-seat passenger of the vehicle. In some embodiments the vehicle 200 may further comprise one or more additional seating positions 230-250 which may be occupied by passengers of the vehicle 200. The vehicle illustrated in Figure 2 comprises a second row of seating positions comprising third to fifth seating positions 230-250. In some embodiments the vehicle 200 further comprises sixth and seventh seating positions 260, 270 which may be occupied by additional passengers. The sixth and seventh seating positions 260, 270 may be occasional- use seating positions located in a rear of the vehicle which may be provided by fold-up seats such as foldable into a floor of the vehicle 200. As illustrated the vehicle 200 shown in Figure 2 may be an estate car or 4x4 vehicle (SUV), although it will be realised that embodiments of the invention are not restricted in this respect and may be applied to other types of vehicle such as two-seat vehicles, four or five seat vehicles etc.

The vehicle 200 comprises an occupancy determining means for determining an occupancy of each seating position 210-270 in the vehicle 200. The occupancy determining means may comprise one or more cameras arranged to provide image data for the interior compartment 205 of the vehicle 200 from which the occupancy determining means is arranged to determine a number of occupants of the vehicle 200 and their respective seating positions i.e. which of available seating positions 210-270 are occupied by a respective occupant.

In one embodiment the occupancy determining means is a seatbelt monitoring system of the vehicle 200. In order to ensure that each occupant of the vehicle 200 is restrained each seating position 210-270 comprises a sensor for determining that an occupant is sitting in the seat and that a restraint associated with the seat, such as a seatbelt, is secured or fastened. In one embodiment the sensor is arranged to detect a weight present on the seat, although it will be realised that this is not limiting and that other sensors may be envisaged. In one embodiment the seatbelt monitoring system is arranged to receive a signal output by each sensor and a corresponding signal indicative of the associated seatbelt being fastened. In this way, the seatbelt monitoring system is able to determine vehicle occupancy which, in one embodiment, comprises the total number of vehicle occupants i.e. a total number of persons within the vehicle 200 and the seating position 210-270 of each vehicle occupant.

The noise configuration unit 1 10 is arranged to receive an input 190 indicative of vehicle occupancy. In one embodiment the noise configuration unit 1 10 is communicatively coupled to a communication bus of the vehicle 200 to receive occupancy data 335 indicative of the vehicle occupancy from the communication bus. The communication bus may, for example, be a CAN bus or an Internet Protocol (IP) based communication bus of the vehicle, such as an Ethernet-based bus, although it will be realised that embodiments of the invention are not limited in this respect. The occupancy data comprises one or both of information indicative of the number of vehicle occupants and the seating position of each vehicle occupant. The occupancy data may be provided from the seatbelt monitoring system of the vehicle 200. The noise configuration unit 1 10 is arranged to select one or more noise cancellation configuration parameters based thereon and to provide an indication 195 of the selected parameters to the noise cancellation unit 120. The noise cancellation unit 120 is arranged to determine at least one noise cancellation signal 151 , 152 based on the one or more noise signals 134, 135 according to the one or more configuration parameters. In this way, generation of the at least one noise cancellation signal 151 , 152 is dynamically configured according to the occupancy data. In particular, the at least one noise cancellation 151 , 152 is determined based on one or both of the number of vehicle occupants and the seating position of each vehicle occupant.

In some embodiments the noise cancellation unit 120 is arranged to only generate the noise cancellation signals 151 , 152 provided to noise cancellation zones 10, 20 which are occupied. For example, as noted above, the first noise cancellation zone 10 may correspond to the location of the driver of the vehicle 200 i.e. seating position 210 and may thus be determined to be always occupied, thus the noise cancellation unit 120 may be arranged to always generate and output the first noise cancellation signal 151 provided to the audio output means 141 associated with the first noise cancellation zone 10. However, the second noise cancellation zone 20 may correspond to a passenger seating position 220 and the noise cancellation signal 152 provided to the audio output means 142 associated with the second noise cancellation zone 20 may only be generated by the noise cancellation unit 120 if it is determined that the second seating position 220 corresponding to the noise cancellation zone 20 is occupied. It will be realised that on-demand provision of noise cancellation signals 151 , 152 is not limited to the seating positions described. In some embodiments, the noise configuration unit 1 10 is arranged to determine configuration parameters which select one or more feedback signals 171 , 172 provided from associated noise error means 161 , 162. That is, the configuration parameters cause the noise cancellation unit 120 to selectively activate use of one or more feedback signals 171 , 172 for the generation of the at least one noise cancellation signal 151 , 152. When selected, the noise cancellation unit 120 is arranged to determine at least one noise cancellation signal 151 , 152 based on the one or more noise signals 134, 135 and the one or more selected feedback signals 171 , 172. In some embodiments, feedback signals 171 , 172 are selectively utilised when provided from one or more noise error means 161 , 162 corresponding to an occupied noise cancellation zone 10, 20. That is, if the noise cancellation zone 10, 20 from which the feedback signal 171 , 172 originates is not occupied then the feedback signal 171 , 172 is not utilised in the generation of noise cancellation signals 151 , 152. In some embodiments, where a plurality of noise error means 161 , 162 are associated with one noise cancellation zone, such as where the noise cancellation zone encompasses multiple occupant seating positions, then only some of the plurality of noise error means 161 , 162 from within the noise cancellation zone may be selected according to the configuration parameters.

Figure 3 schematically illustrates a structure of the noise configuration unit 1 10 and the noise cancellation unit 120 according to an embodiment of the invention.

The noise configuration unit 1 10 comprises a processing unit 310 for operatively executing an algorithm for determining the one or more configuration parameters of the noise cancellation unit 120. The determined one or more configuration parameters are provided to the noise cancellation unit 120 as parameters 305 via a communication path.

The processing unit 310 is communicably connected to an interface 320 for receiving the occupancy data 325. As explained below, the interface 320 may be arranged to communicate with one or more systems of the vehicle to determine the occupancy data 325 associated with the vehicle. The occupancy data 325 may indicate the number of occupants of the vehicle. In some embodiments the occupancy data 325 also indicates the seating position 210-270 of the occupants. The interface 320 may be communicably coupled with a communication bus of the vehicle to receive the occupancy data 325 from the one or more systems of the vehicle. For example, the interface may communicate with a seatbelt monitoring system of the vehicle 200 to determine a number of occupants of the vehicle based on a number of seatbelts fastened. Alternatively the number of occupants may be determined from a system using one or more interior cameras of the vehicle 200. It will be realised that the number of occupants may be determined in other ways.

The one or more configuration parameters 305 of the noise cancellation unit 120 are determined by the processing unit 310 based on one or both of the received occupancy data 325. In some embodiments the configuration parameters 305 may further be determined on received vibro-acoustic data. The configuration parameters 305 may be a plurality of configuration parameters 305 for providing to the noise cancellation unit 120, as will be explained. The configuration parameters 305 may be associated with one or more transfer functions of the noise cancellation unit 120. In particular, the configuration parameters 305 may be one or more coefficients of the one or more transfer functions of the noise cancellation unit 120. In one embodiment, the configuration parameters 305 may comprise a plurality of coefficients associated with at least one transfer function of the noise cancellation unit 120. In some embodiments the configuration parameters 305 alternatively or additionally select one or more feedback signals 171 , 172 for use in generating the one or more noise cancellation signals 151 , 152.

The noise configuration unit 1 10, in some embodiments, comprises a parameter data store 340. The parameter data store 340 stores data representing a plurality of configurations of the noise cancellation unit 120. The processing unit 310 is arranged to select one of the configurations represented in the data store 340 according to the occupancy data 325 received via the interface 320. The data representing the plurality of configurations of the noise configuration unit 1 10 may comprise a plurality of sets of data for configuring the noise cancellation unit 120 to a respective configuration. The plurality of sets of data may be a plurality of tables of configuration data, although it will be realised that embodiments of the invention are not limited in this respect. In one embodiment, the parameter data store stores a plurality of sets of the one or more coefficients of the one or more transfer functions of the noise cancellation unit 120 which are selected according to the occupancy data 325. The parameter data store 340 may store data indicative of which of the feedback signals 171 , 172 are to be utilised for each configuration.

In one embodiment, the noise cancellation unit 120 comprises a first data store 360 storing at least one reference transfer function (RTF) and a second data store 370 storing at least one speaker transfer function (STF). Although illustrated as first and second data stores 360, 370 it will be realised that the data stores may be unified i.e. the noise cancellation unit 120 may comprise only one data store including both RTF and STF. The noise cancellation unit 120 further comprises a processing unit 350 communicably connected to the data stores 360, 370. The processing unit 350 comprises one or more processing devices for operatively executing an algorithm for determining the noise cancellation signal which is output via an interface 355. The algorithm is based upon the one or more configuration parameters received from the noise configuration unit 1 10.

The RTF represents a transfer function from the one or more reference devices 131 , 132 such as the vibro-acoustic devices, for example microphones or accelerometers. The RTF may be from the acoustic sensing devices 131 , 132 to one or more of the noise cancellation zones 10, 20. A respective RTF may be provided for each cancellation zone 10, 20. The RTF may comprise a plurality of coefficients. The RTF may be used to configure a corresponding filter. The RTF represents how noise is caused by acoustic signals at the acoustic sensing devices 131 , 132. For example, the RTF may place emphasis on acoustic signals in one or more frequency ranges resulting in noise within the first noise cancellation zone 10, although it will be appreciated that this is not limiting.

The STF represents a transfer function from the one or more audio output devices 141 , 142. The STF may represent a transfer function from at least one audio output device 141 , 142 to one of the noise cancellation zones 10, 20. At least one respective STF may be provided for each cancellation zone 10, 20. Each STF may be configured according to a respective number of occupants of the vehicle. That is, as the number of occupants may influence a signal output by a speaker 141 , 142 being received in one of the noise cancellation zones 10, 20. Respective STFs may be provided for one or both of the number of occupants and seating positions of those occupants within the vehicle. Each STF may comprise a plurality of coefficients. For example, the STF may place emphasis on acoustic signals in one or more frequency ranges resulting in noise within the particular noise cancellation zone 10, 20.

The configuration parameters 305 received at the noise cancellation unit 120 may configure one or both of the at least one RTF or STF according to the occupancy of the vehicle. In one embodiment a plurality of RTFs and/or STFs are stored within the noise cancellation unit 120 and are selected according to the configuration parameters 305 received from the noise configuration unit 1 10.

In some embodiments the noise cancellation unit 120 is operative based on a plurality of filter coefficients to determine each noise control cancellation signal 151 , 152. Each acoustic device 141 , 142 may be associated with one or more filter coefficients. In particular, each acoustic device 141 , 142 may be associated with a plurality of filter coefficients where each filter coefficient corresponds to a respective reference acoustic pattern. The filter coefficients may be represented as w_km[i] which denotes a filter coefficient to drive an acoustic device m based on a /c-th reference acoustic pattern.

The noise configuration unit 1 10 is arranged to determine one or more operational characteristics of the vehicle.

Figure 4 illustrates a method 400 according to an embodiment of the invention. The method 400 is a method of generating one or more noise cancellation signals 151 , 152 for reducing noise within a vehicle. The method 400 may be performed by the noise cancellation system 100 as described above according to an embodiment of the invention.

In step 410 occupancy data 325 is received. The occupancy data 325 is indicative of vehicle 200 occupancy. The occupancy data 325 may be indicative of the number of occupants of the vehicle 200. In some embodiments the occupancy data 325 indicates the seating position 210-270 of the occupants. In some embodiments it is assumed, by default, that the seating position 210 corresponding to the driver of the vehicle 200 is occupied and thus the occupancy data 325 may only indicate the presence, and in some embodiments seating position 22-270, of further vehicle occupants. In step 420, based on the received occupancy data 325, one or more configuration parameters of the noise cancellation unit 120 are determined. The one or more configuration parameters may be determined by processing the received occupancy data by a

predetermined algorithm. The algorithm may select configuration parameters from the parameter data store 340 associated with occupancy data having a greatest similarity to the received occupancy data 325. Thus in step 430 the configuration of the noise cancellation unit 120 is determined. The configuration may be selected from amongst a plurality of predetermined configurations. Each configuration may be represented by one of more configuration parameters which are provided from the noise configuration unit 1 10 to the noise cancellation unit 120.

The one or more configuration parameters may be coefficients associated with one or more transfer functions. The configuration parameters may configure one or more filters according to the determined operational characteristics. The configuration parameters may select one or more feedback signals 171 , 172 for use in determining the one or more noise cancellation signals 151 , 152. In particular, in some embodiments, the configuration parameters may be indicative of a weighting value associated with one or more feedback signals 171 , 172. The weighting value may define an amount of influence of the feedback signal 171 , 172 in determining the one or more noise cancellation signals 151 , 152. For example a feedback value of a first predetermined value, such as 0, may indicate that the feedback signal is not used in determining the one or more noise cancellation signals 151 , 152, whereas a feedback value of a second predetermined value, such as 1 , may indicate that the feedback signal is fully utilised. Intermediate feedback signals reduce the influence of the feedback signal 171 , 172 accordingly.

In step 430 one or more noise signals 134, 135 indicative of noise associated with the vehicle are received. The one or more noise signals are provided from respective acoustic sensing devices 131 , 132 as explained above.

In step 440 one or more noise cancellation signals 151 , 152 are generated based on the configuration selected in step 420. The one or more noise cancellation signals 151 , 152 are generated based on the output of the acoustic sensing devices 131 , 132. In some

embodiments, the noise cancellation signals 151 , 152 may be further generated, in a closed- loop system, based on the one or more feedback signals 171 , 172 to the noise cancellation system 100 indicative of noise within respective noise cancellation zones 10, 20. Figure 5 illustrates a vehicle 500 according to an embodiment of the invention. The vehicle comprises a noise cancellation system 100 such as described above in relation to the preceding figures.

Advantageously embodiments of the invention adapt a configuration of the noise cancellation system to occupancy of the vehicle 200, 500, such that at least one noise cancellation signal 151 , 152 is responsive to changes in the number and, in some embodiments seating position 210-270 of vehicle occupants. In this way noise cancellation may be improved. It will be appreciated that embodiments of the present invention can be realised in the form of hardware, software or a combination of hardware and software. Any such software may be stored in the form of volatile or non-volatile storage such as, for example, a storage device like a ROM, whether erasable or rewritable or not, or in the form of memory such as, for example, RAM, memory chips, device or integrated circuits or on an optically or magnetically readable medium such as, for example, a CD, DVD, magnetic disk or magnetic tape. It will be appreciated that the storage devices and storage media are embodiments of machine-readable storage that are suitable for storing a program or programs that, when executed, implement embodiments of the present invention. Accordingly, embodiments provide a program comprising code for implementing a system or method as claimed in any preceding claim and a machine readable storage storing such a program. Still further, embodiments of the present invention may be conveyed electronically via any medium such as a communication signal carried over a wired or wireless connection and embodiments suitably encompass the same.

All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings), may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed. The claims should not be construed to cover merely the foregoing embodiments, but also any embodiments which fall within the scope of the claims.

Claims

1 . A noise cancellation system, comprising:

noise cancellation parameter selection means for receiving occupancy data indicative of vehicle occupancy and for determining one or more noise cancellation configuration parameters based thereon; and

noise cancellation means for receiving one or more noise signals and for determining at least one noise cancellation signal based on one or more noise signals according to the one or more configuration parameters.

2. The system of claim 1 , wherein the configuration parameters are parameters associated with at least one transfer function for determining the at least one noise cancellation signal based on the one or more noise signals.

3. The system of claim 2, wherein the parameters associated with the at least one function are one or more filter coefficients.

4. The noise cancellation system of claim 1 , 2 or 3 wherein:

the configuration parameters selectively activate one or more feedback signals output by associated noise error means; and

the noise cancellation means is arranged to determine the at least one noise cancellation signal based on the one or more noise signals and the one or more feedback signals.

5. The noise cancellation system of any preceding claim, wherein the noise cancellation means is arranged to one or both of apply a weighting value to one or more feedback signals and selectively activate one or more feedback signals based on the configuration parameters.

6. The noise cancellation system of claim 4 or claim 5, wherein each noise error means is arranged within a respective noise cancellation zone and the noise cancellation means is arranged to output a plurality of noise cancellation signals each provided to a respective noise cancellation zone.

7. The noise cancellation system of any preceding claim, wherein: the noise cancellation means is arranged to selectively output a plurality of noise cancellation signals associated with a plurality of noise cancellation zones according to the configuration parameters; and

the noise cancellation parameter selection means is arranged to determine the configuration parameters to select one or more active noise cancellation zones based on the occupancy data.

8. The noise cancellation system of any preceding claim, wherein the occupancy data is indicative of a number of occupants of a vehicle.

9. The noise cancellation system of claim 8, wherein the occupancy data is indicative of a seating position of the occupants of the vehicle.

10. The noise cancellation system of any preceding claim, wherein the occupancy data is received from an occupancy determining means of a vehicle.

1 1 . The noise cancellation system of claim 10, wherein the occupancy determining means is a seatbelt monitoring means.

12. The noise cancellation system of claim 2 or any claim dependent thereon, wherein the transfer function is a speaker transfer function (STF) indicative of a transfer function from one or more audio output devices.

13. The noise cancellation system of claim 2 or any claim dependent thereon, wherein the transfer function is a reference transfer function (RTF).

14. A method of generating a noise cancellation signal, comprising:

receiving occupancy data indicative of vehicle occupancy;

selecting one or more noise cancellation configuration parameters based on the occupancy data;

receiving one or more noise signals;

generating a noise cancellation signal based on the one or more noise signals according to the selected one or more configuration parameters.

15. The method of claim 14, wherein the configuration parameters are parameters associated with a transfer function for determining the at least one noise cancellation signal based on the one or more noise signals.

16. The method of claim 15, wherein the parameters associated with the transfer function are one or more filter coefficients.

17. The method of claim 14, 15 or 16, comprising:

selectively activating one or more feedback signals received from one or more associated noise error means ; and

determining the at least one noise cancellation signal based on the one or more noise signals and the activated one or more feedback signals .

18. The method of any of claims 14 to 17, comprising one or both of applying a weighting value associated with one or more feedback signals and selectively activating one or more feedback signals based on the configuration parameters.

19. The method of claim 17 or claim 18, wherein each noise error means is arranged within a respective noise cancellation zone and the method comprises outputting a plurality of noise cancellation signals to the respective noise cancellation zones.

20. The method of any of claims 14 to 19, comprising:

selectively outputting a plurality of noise cancellation signals associated with a plurality of noise cancellation zones according to the configuration parameters; and determining the configuration parameters to select one or more active noise cancellation zones based on the occupancy data.

21 . The method of any of claims 14 to 20, wherein the occupancy data is indicative of a number of occupants of a vehicle.

22. The method of any of claims 14 to 21 , wherein the occupancy data is indicative of a seating position of the occupants of the vehicle.

23. The method of any of claims 14 to 22, wherein the occupancy data is received from an occupancy determining means of a vehicle.

24. The method of any of claims 14 to 23, wherein the occupancy determining means is one of a seatbelt monitoring means, weight determining means, optical means or a personal communication means; optionally the personal communication means is a mobile phone.

25. A vehicle comprising a noise cancellation system as claimed in any of claims 1 to 13.

26. Computer software which, when executed by a computer, is arranged to perform method according to any of claims 14 to 24; optionally the computer software stored on a computer-readable medium.