Patent Application
20140233748
The disclosure relates to noise cancellation, and more particularly, to the reduction of engine and other undesirable noise within a passenger cabin of an automobile.
Automotive vehicles are designed for efficiency and high performance. The engines and transmissions that provide acceleration and handling can generate undesirable sounds that diminish the driving experience. For example, an engine can produce a high frequency noise that cannot be easily quieted by traditional noise countermeasures. The high frequency noise tones vary with the revolutions per minute (rpm) of the engine and affect passengers differently depending upon their chair positions, height, and posture within the vehicle.
In a particular embodiment, an apparatus includes a first speaker positioned forward of a steering wheel of a vehicle. The first speaker generates a first signal configured to acoustically cancel noise produced by operation of the vehicle. A second speaker is positioned forward of the steering wheel. The second speaker generates a second signal to acoustically cancel the noise produced by the operation of the vehicle.
In another embodiment, an apparatus includes a speaker positioned forward of a steering wheel of a vehicle. The speaker is configured, in response to a control signal, to generate a noise cancelling signal to acoustically cancel noise produced by operation of the vehicle. The apparatus further includes a plurality of microphones. Each of the plurality of microphones are configured to convert sensed sound into one of a plurality of input signals. A controller in communication with the speaker and the plurality of microphones is configured to receive the plurality of input signals. The controller executes an active noise cancellation algorithm to generate the control signal.
In another embodiment, a method of cancelling noise in a vehicle includes positioning a first speaker forward of a steering wheel of a vehicle. The first speaker generates a first signal to acoustically cancel noise produced by operation of the vehicle. A second speaker is positioned forward of the steering wheel. The second speaker generates a second signal to acoustically cancel the noise produced by the operation of the vehicle.
Positioning speakers forward within a vehicle facilitates independent and localized control of noise cancellation processes. When used in combination with aft positioned speakers and sensor microphones, the forward positioned speakers provide control to cancel sinusoidal noise up to and beyond 180 hertz (Hz) in a spatial area large enough to accommodate passengers having different heights, chair positions, and postures. Because each speaker controller receives input from multiple microphones, relatively few microphones may be used to produce a desired acoustic result. Embodiments of the active noise cancellation system create a large noise cancellation zone. For example, the noise cancellation zone in a vehicle spans four seats with a wide buffer of silence around each seat. A large cancellation zone minimizes spatial challenges and noise variance conventionally attributable to passengers having different heights and postures. Embodiments of the active sound management system further reduce the reliance on other noise countermeasures, enabling manufacturers to produce vehicles that are lighter and more efficient with improved sound and performance characteristics, contributing to a better driving experience.
These and other advantages and features that characterize embodiments are set forth in the claims annexed hereto and forming a further part hereof. However, for a better understanding of the invention, and of the advantages and objectives attained through its use, reference should be made to the Drawings and to the accompanying descriptive matter in which there are described exemplary embodiments.
An embodiment of an active sound management system includes noise cancellation capable speakers positioned forward of a steering wheel, such as within an instrument panel of a vehicle. The forward speaker placement increases the range of frequency of the noise that can be cancelled over a sufficiently large spatial area. Controllers for the speakers operate within the sound system of the vehicle and continuously receive information relating to engine noise. At the same time, each speaker controller concurrently receives inputs from multiple microphones in the vehicle cabin. The wave characteristics of the targeted engine noise are determined. Acoustically opposite signals are independently generated by each speaker to cancel the detected sound, reducing unwanted engine noise in the cabin. The active sound management system operates continuously and automatically.
Positioning speakers on top of the instrument panel provides independent and localized control of noise cancellation processes. The forward positioned speakers may be driven by a controller using an adaptive, active sound management algorithm that allows for the independent control of individual speakers or groups of speakers. When used in combination with aft positioned speakers and sensor microphones, the forward positioned speakers of an embodiment provide enough control to cancel sinusoidal harmonic frequency noise greater than 180 Hz over a large spatial area. The forward positioned speakers provide an extra degree of freedom for cancelling unwanted noise. The forward positioned speakers complement other speakers, positioned aft of the steering wheel, by contributing to noise cancellation of the entire group of speakers. Embodiments of the active noise cancellation system thus achieve upper frequency range noise cancellation.
A particular embodiment of the active noise cancellation system creates a large noise cancellation zone. For example, an illustrative noise cancellation zone spans four seats with a wide buffer of silence around each seat. Speakers are installed on the center, left, and right-hand sides of a top surface of an instrument panel of the vehicle to cancel high frequency noise (e.g., including and beyond 180 Hz) simultaneously in an area spanning all four seats.
Embodiments of the active sound management system reduce the reliance on other noise countermeasures, enabling manufacturers to produce vehicles that are lighter and more efficient with improved sound and performance characteristics, contributing to a better driving experience.
As shown in
The speakers 104, 106, 108, 114, 116, 118, 120, 122 each receive inputs from multiple microphones 138, 140, 142, 144 distributed inside the cabin of the automobile 102. For example, the microphones 138, 140, 142, 144 of
The active sound management system 100 generates large noise cancellation zones 148, 150, 152, 154 associated with each seat 126, 128, 130, 132. The noise cancellation zones 148, 150, 152, 154 are relatively larger than smaller noise cancellation zones 160, 162, 164, 166 generated close to the microphones 138, 140, 142, 144. The noise cancellation zones 148, 150, 152, 154 reduce spatial challenges and noise variance conventionally attributable to passengers having different heights, chair positions, and postures. For example, the noise cancellation zones 148, 150, 152, 154 may each have a spatial dimension (e.g., a height, a width, and/or a length) larger than seven and one half inches in which a noise cancelling frequency of greater than 180 Hz is present. At 180 Hz, for instance, the area of the noise cancelation may have a dimension that is longer than one tenth of a wavelength. At another frequency, a noise cancellation zone having an illustrative spatial dimension of larger than a foot may be achieved.
While the forward speakers 104, 106, 108 are shown in
According to a particular embodiment, the first and the second speakers 202, 204 operate independently to generate respective noise cancelling signals. Accordingly, each speaker 202, 204 is driven by a first and a second controller 206, 208, respectively. More particularly, the first controller 206 executes an active sound management algorithm 210 to generate a first noise cancelling signal at the first speaker 202. The second controller 208 executes an active sound management algorithm 212 to generate a second noise cancelling signal at the second speaker 212.
The first and the second controllers 206, 208 each receive inputs from the first and the second microphones 214, 216. The first and the second microphones 214, 216 are similar to the microphones 138, 140, 142, 144 of
Enabling each speaker to operate as an independent noise cancelling mechanism allows high frequency sinusoidal frequencies to be cancelled. The controller of each speaker processes input signals from all of the microphones 214, 216. Receiving inputs from all of the microphones 214, 216 enables multiple input signals to be weighted and processed in together. Alternatively, according to a particular embodiment, the first and the second speakers 202, 204 are at times operated in conjunction with one another, e.g., driven in mono. For instance, conditions could exist where it is beneficial to reduce the degrees of freedom, such as where there are too many potential solutions that could use large amounts of power with relatively little noise cancellation. An illustrative condition is where the outputs from speakers 202, 204 are automatically determined to be working against each other, e.g., cancelling one another out. In such a circumstance, operation of the speakers is reconfigured to operate in a paired, non-autonomous mode (automatic reconfiguration is a current research topic and should not be disclosed).
According to a particular embodiment, the first and the second speakers 202, 204 are alternatively or additionally controlled using a master controller 220. Where the first and the second controllers 206, 208 are present, the master controller 220 modifies or tunes output wavelength characteristics, or otherwise coordinates signal calculations made by the first and the second controllers 206, 208. For example, the master controller 220 may act to turn all the speakers off under certain pre-defined conditions, such as when a door is opened. The master controller 220 reacts automatically to sensed sound data, and additionally or alternatively uses empirical results gleaned from testing in an automotive environment.
At 304, the speakers are connected to controllers that receive input signals from multiple sound sensing microphones. As shown in
The speaker controllers are programmed at 306 to independently execute the active sound management algorithm to cancel undesired noise within the automobile cabin. For instance, the active sound management algorithm is executed for each of the speakers 104, 106, 108, 114, 116, 118, 120, 122 of
The speaker controllers receive microphone and engine noise information at 308. In
At 310, the speaker controllers are programmed or otherwise configured such that their output can be adjusted. While each speaker controller operates independently to cancel noise according to the active sound management algorithm, a particular embodiment may adjust one or more speakers based on the collective output of the speakers. The adjustment may include modifying the wave characteristics of the noise cancellation signals output from one or more of the speakers.
At 312, the speaker controllers independently and continuously produce noise cancelling signals. For example, the speakers 104, 106, 108, 114, 116, 118, 120, 122 of
Those skilled in the art may make numerous uses and modifications of and departures from the specific apparatus and techniques disclosed herein without departing from the inventive concepts. Consequently, the disclosed embodiments should be construed as embracing each and every novel feature and novel combination of features present in or possessed by the apparatus and techniques disclosed herein and limited only by the scope of the appended claims, and equivalents thereof.
