Sound Cancellation Using Microphone Projection

Abstract

In some embodiments, an audio system, method, and computer-readable medium having program code thereon receives a harmonic signal associated with a rotating device, such as a vehicle drivetrain, and provides a harmonic cancellation (or improved) signal. The harmonic cancellation signal is converted into an acoustic signal, and a feedback sensor, such as a microphone, detects an error signal representative of acoustic energy at a first location in the environment. A projection filter filters the error signal to provide an estimated error signal at a second location in the environment, such as at the location of an occupant's ear. An adaptation module adjusts the cancellation signal based on the estimated error signal.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 62 / 848,888, entitled "SOUND CANCELLATION USING MICROPHONE PROJECTION," filed May 16, 2019, which is incorporated herein in its entirety for all purposes. [Background technology]

[0002] SUMMARY The present disclosure relates generally to systems and methods for minimizing error signals representative of undesirable sounds at a location remote from a feedback sensor. Summary of the Invention

[0003] All embodiments and features mentioned below can be combined in any technically possible manner.

[0004] Various aspects include cancellation systems, methods, and / or program code for canceling or reducing undesirable sounds, particularly harmonics of rotating equipment such as engine or other drivetrain harmonics, and / or harmonics of other equipment such as air conditioners, fans, motor drives, etc. The system, method, or program code includes (or implements) a cancellation filter configured to generate a cancellation signal. The cancellation signal may be based on a reference signal received from a sensor, such as a tachometer or other sensor indicating rotation, such as engine or drivetrain rotation (e.g., revolutions per minute), that provides a signal representative of the harmonics. A transducer is disposed at a first location in the acoustic environment, such as a vehicle cabin, and configured to receive the cancellation signal and convert the cancellation signal into a cancellation audio signal in the environment. A feedback sensor, such as a microphone, may be disposed at a second location in the environment and output a feedback signal, which may be considered an error signal, the feedback signal being representative of the sound at the second location. One or more projection filters may be configured to filter the feedback signal and / or the cancellation signal to provide an estimation error signal representative of an estimate of undesired harmonic sound at a third location remote from the first and second locations. The adjustment module may be configured to adjust the cancellation filter based on the estimation error signal such that the cancellation audio signal destructively interferes with the undesired sound at the third location.

[0005] According to various embodiments, the sensor may be indicative of the rotational speed of the engine and may provide harmonic information of the engine. In some embodiments, the sensor may provide rotational information regarding other portions of the drivetrain, such as the transmission, transaxle, wheels, etc. In certain embodiments, the sensor may provide rotational information regarding other rotating equipment, such as, for example, drive motors for operating windows, wipers, etc., air conditioners, fans, etc. In some cases, the sensor may further provide one or more substantially sinusoidal signals indicative of one or more harmonics of the rotating equipment.

[0006] In certain embodiments, the feedback sensor may be a microphone for detecting acoustic energy in an environment, such as the vehicle cabin, and the microphone location may be a roof, pillar, headliner, or other location. In various embodiments, the third location is the expected location of the occupant's ear. Thus, the feedback sensor signal may be a remote microphone signal, and the estimation error signal may represent an estimate of the acoustic energy at the occupant's ear. Thus, the estimation error signal may represent a virtual microphone located at a third location, e.g., a roof microphone "projected" to the location of the occupant's ear.

[0007] In various embodiments, the estimated error signal is based on an estimate of an acoustic relationship between the second location (microphone) and a third location (the occupant's ear). In certain embodiments, the estimated error signal can also be based on an estimate of an acoustic relationship between the first location (transducer) and a third location (the occupant's ear) and an estimate of an acoustic relationship between the first location (transducer) and the second location (microphone).

[0008] In certain embodiments, the one or more projection filters include a first filter configured to estimate a relationship between the second location and a third location, the first filter configured to receive and filter a feedback signal (undesirable sound at the second location) and output a first filtered signal that is an estimate of the undesirable sound at the third location. The first filter may be referred to as a projection filter because it "projects" a feedback sensor (microphone) to an alternative location (occupant's ear), for example, to provide an estimate of what the feedback signal would be like if the feedback sensor were located at the alternative location.

[0009] In some embodiments, the one or more projection filters further comprise a second filter configured to estimate a relationship between the first location (the transducer) and a third location (the occupant's ear), the second filter configured to receive and filter the cancellation signal and output a second filtered signal that is an estimate of the cancellation audio signal at the third location, the second filtered signal configured to cancel a portion of the first filtered signal based on the cancellation audio signal received at the feedback sensor when the first filtered signal and the second filtered signal are summed.

[0010] In certain embodiments, one or more projection filters may be selected based on particular vehicle operating conditions that may affect the acoustic relationship between the second location (e.g., a microphone) and a third location (e.g., an occupant's ear) and / or the transfer path between the first location (e.g., a transducer) and a third location (e.g., an occupant's ear), also known as a secondary path transfer function. Thus, the particular vehicle and / or powertrain operating conditions upon which the filter selection is based may include one or more of the following: engine rotational rate (RPM), transmission RPM, engine output torque (τ), transmission output torque, throttle position, manifold vacuum, engine spark timing / rate, rate of change of engine and / or transmission RPM (e.g., delta-RPM, ΔRPM), load / loading and distribution of same, acceleration (transfers load to rear suspension), braking / deceleration (transfers load to front suspension), turning / cornering acceleration (transfers load from side to side), and / or suspension control and / or damper stiffness (e.g., hydraulic, pneumatic, electronically controlled suspension components).

[0011] In certain examples, one or more projection filters may be selected based on certain conditions that may affect the vehicle cabin acoustics, such as those that may affect the relationship between the second location and the third location and / or the communication path between the first location and the third location. The conditions on which the filter selection is based may include one or more of the following: window position (how open / closed), sunroof position (how open / closed), door ajar (e.g., hatch open / closed), seat position (e.g., height, tilt, front / rear), rear seats folded or stowed, occupancy (number of occupants, number of seats, weight, etc.) that may be detected by airbag occupancy sensors, cameras, etc.

[0012] In various embodiments, the one or more projection filters comprise at least one predictive filter, such that an estimate of the undesirable sound at the third location is an estimate of the undesirable sound at the third location at a future time.

[0013] Further other aspects, embodiments, and advantages of these exemplary aspects and examples are discussed in detail below. The examples disclosed herein can be combined with other examples in any manner consistent with at least one of the principles disclosed herein, and further, references to "an example," "some examples," "an alternate example," "various examples," "one example," and the like are not necessarily mutually exclusive and are intended to indicate that a particular feature, structure, or characteristic described may be included in at least one embodiment. Appearances of such terms in this specification do not necessarily all refer to the same embodiment. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of an exemplary sound cancellation system. [Diagram 2] FIG. 2 is a schematic diagram of another exemplary sound cancellation system. [Diagram 3] 1 is a schematic diagram of an exemplary tuning system. [Figure 4] FIG. 2 is a schematic diagram of another exemplary sound cancellation system. [Diagram 5] FIG. 2 is a schematic diagram of another exemplary sound cancellation system. [Figure 6] FIG. 2 is a schematic diagram of another exemplary sound cancellation system. [Figure 7] FIG. 2 is a schematic diagram of another exemplary sound cancellation system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Various aspects of at least one example are discussed below with reference to the accompanying drawings, which are not intended to be drawn to scale. These drawings are included to provide illustration and further understanding of the various aspects and examples, and are incorporated in and constitute a part of this specification, but are not intended as a definition of the limitations of the invention. In the drawings, identical or nearly identical components illustrated in various figures may be labeled with similar letters or numerals. For clarity, every component may not necessarily be labeled in every figure.

[0016] Sound cancellation systems that cancel or reduce undesirable sounds within a defined volume, such as harmonic cancellation in a vehicle cabin, often use a feedback sensor (such as a microphone) to generate an error signal (or feedback signal) representative of the residual uncancelled sound. This error signal is fed back to an adaptive filter that adjusts the cancellation signal in an attempt to minimize the residual uncancelled sound.

[0017] However, in some situations, the feedback sensor may not be located in an optimal location. For example, in a vehicle situation, the feedback sensor may be located in the roof, pillar, or headrest, but the undesired sound should be cancelled at the occupant's ear. As a result, the error signal indicates the error at the feedback sensor, but not at the occupant's ear. This is undesirable, since the purpose of the cancellation system is to cancel the undesired sound at the occupant's ear. However, placing a microphone at the occupant's ear may be impractical and unacceptable to the occupant. However, in some embodiments, a prior measurement with a microphone placed at the ear location may determine the acoustic relationship between the ear location and the feedback sensor location. Thus, the feedback sensor signal (e.g., roof microphone) may be "projected" to an equivalent ear microphone signal. In other words, the roof microphone signal may be filtered (based on the acoustic relationship between the two locations) to provide a virtual ear microphone signal. In various embodiments, the acoustic relationship between the location of the feedback sensor and the location of the occupant's ear may vary depending on vehicle and cabin conditions as described herein, and thus the filters may be selected based on such vehicle and / or cabin conditions.

[0018] Additionally, in vehicles and other situations, sound cancellation audio signals are typically delayed by about 5 milliseconds because the audio signal must travel from speakers located along the perimeter of the vehicle cabin to the occupant's ears (e.g., the cancellation audio signal must travel from about 5 feet away from the occupant's ear, and the speed of sound is about 1 foot / ms). This delay prevents optimal cancellation because the cancellation audio signal perceived by the occupant is directed to a sound that has already occurred. Thus, some embodiments may include a feature that predicts future values ​​of residual sound at the occupant's ear without placing a microphone at the occupant's ear. Further details of predicting sound or residual sound can be found in U.S. Patent No. 10,629,183, entitled SYSTEMS AND METHODS FOR NOISE-CANCELLATION USING MICROPHONE PROJECTION, issued April 21, 2020, and incorporated herein in its entirety for all purposes.

[0019] Various embodiments disclosed herein are directed to a cancellation system that estimates an error signal representative of residual uncanceled sound at a distance from the feedback sensor, the estimation being based in one embodiment on available information, namely from remote reference microphones and knowledge of the relationship between those remote microphones and the sound fields at the occupants' ears, and of the output of the sound cancellation system itself.

[0020] Based on the estimated error signal, the resulting adjustments to the adaptive filter minimize the estimated error signal, thus canceling the undesired sound at the remote location rather than at the feedback sensor, e.g., effectively projecting the feedback sensor to the remote location, which may alternatively be understood as shifting the cancellation zone from the feedback sensor to a location away from the feedback sensor.

[0021] FIG. 1 is a schematic diagram and / or signal flow diagram of an exemplary sound cancellation system 100 including a signal source 110, a cancellation filter 120, a transducer 130 (e.g., a loudspeaker or driver), a microphone 140 (feedback sensor), and an adaptive module 150. In various embodiments, the signal source 110 may be a signal generator that provides a reference signal 112 that may include components representative of harmonics of rotating equipment associated with an environment. For example, in a vehicle, the drivetrain, e.g., engine, transmission, transaxle, wheels, etc., may generate various harmonics that generate audible sounds within the vehicle. The noise cancellation system 100 may be configured to reduce the audible harmonics. Thus, the signal source 110 may generate the reference signal 112 that is representative of the harmonics of the rotating equipment. Thus, in some embodiments, the signal source 110 may receive rotational information from a sensor 114, such as a rotational speed, which may be rotations per minute (RPM). In some embodiments, reference signal 112 may include multiple sinusoidal signals at various frequencies representing one or more harmonics of the rotating equipment.

[0022] The cancellation filter 120 receives the reference signal 112 and filters the reference signal 112 to generate a cancellation signal 122. The cancellation signal 122 is a driver signal that drives a transducer 130 to generate a cancellation audio signal 132 in the environment, for example, in some embodiments, the cabin of a vehicle. The microphone 140 is a feedback sensor that detects sounds in the environment and provides an error signal 142. The adaptation module 150 receives the reference signal 112 and the error signal 142 and updates the cancellation filter 120 to minimize the error signal 142. Thus, the adaptation module 150 adjusts the cancellation filter 120 such that harmonic sounds at the microphone 140 are reduced.

[0023] 1, when the microphone 140 is ideally located at the occupant's ear, the system effectively reduces or eliminates the harmonic sound at the occupant's ear. The cancellation audio signal 132 is generated based on a transfer function 160, T, which is the transfer function from the driver (location of the transducer 130) to the ear (location of the microphone 140). DE , to microphone 140. In various embodiments, adaptive module 150 may be programmed with an estimate of transfer function 160 and may implement an adaptive algorithm, such as any of a variety of least mean squares (LMS) or alternative algorithms, to adjust the transfer function, W, of cancellation filter 120 to minimize error signal 142.

[0024] 1 contemplates microphones 140 located at or in close proximity to the occupant's ears, it may generally be unacceptable or impractical to place a microphone close to the occupant's ears. In various embodiments, such feedback microphones may instead be located near but away from the occupant's ears, such as in the roof, headliner, headrest, pillars, or other locations.

[0025] 2 illustrates another example sound cancellation system 200 similar to sound cancellation system 100, except that a feedback sensor, a microphone 240, is located away from the occupant's ear 244. Thus, an error signal 242 from the microphone 240 may not represent undesirable sound at the location of the occupant's ear 244. The sound cancellation system 200 of FIG. 2 operates in the same or similar manner as the sound cancellation system 100 of FIG. 1, thereby reducing harmonic sound at the location of the microphone 240, but not necessarily the occupant's ear 244. Thus, the sound cancellation system 200 is not optimized to reduce harmonic sound at the occupant's ear 244.

[0026] However, the sound at the microphone 240 has a relationship 246 to the sound at the occupant's ear 244. The relationship 246 depends on the source of the sound and the manner in which the audible vibrations are transmitted from the source through the acoustics of the environment. For example, a particular harmonic, when operating at a particular frequency, can generate a particular relationship 246 of sound between the harmonic sound at the occupant's ear 244 and the harmonic sound at the microphone 240, e.g., with respect to amplitude and phase. In various embodiments, different harmonics may generate different relationships 246 even when operating at the same frequency (e.g., a first harmonic may generate a particular frequency at a given RPM, as does a second harmonic at a lower RPM) (e.g., a 100 Hz sound signal may be a first harmonic at one RPM and a second harmonic at another RPM). Further, in various embodiments, relationship 246 may change with any of a variety of operating conditions, such as torque, acceleration, vehicle load, etc., as well as with acoustic characteristics of the environment, such as seat position, window condition, vehicle occupancy, load, changes over time, etc.

[0027] In various embodiments, the relationship 246 is pre-measured for any number of harmonics of interest (to accommodate different system objectives) and under various conditions, and a projection filter is generated to filter the error signal 242 to effectively account for or reverse the effect of the relationship 246, such that the filtered signal represents an estimate of the error signal at the occupant's ear 244. According to various embodiments, the relationship 246 is measured for each harmonic over a range of rotational speeds, and thus over a corresponding range of frequencies. The relationship 246 may then be equivalently modeled as a transfer function as a function of frequency, e.g., a set of phase and amplitude relationships over the range of frequencies of a given harmonic. Thus, in various embodiments, the projection filter transfer function effectively projects the microphone 240 to the location of the occupant's ear 244 and relates a remote location (e.g., in some embodiments, a roof location) to the ear location, and is therefore referred to herein as W RE It is sometimes called.

[0028] 3 illustrates an example tuning system 300 that may be used in some embodiments to measure one or more relationships 246 between sounds at an ear location and a remote location under various conditions. A microphone 140 is positioned at the ear location and a microphone 240 is positioned at the remote location, e.g., roof, headliner, pillar, etc., where the microphone will be located during operation. A sine wave source 310 provides selected harmonics 320, k, (e.g., k=1, 2, 3, ..., n) based on the rotational speed (e.g., RPM) of the equipment whose sound it is desired to modify / cancel, such as according to expression (1).

number

[0029] For clarity, each phasor contains amplitude and phase information. The phase of the audio source (the rotator) may be ambiguous, but the phasor E k and R k are expected to have a substantially constant relative phase, e.g., the phase of one relative to the other is fixed, as are their relative amplitudes, characterizing relationship 246 for a given harmonic, k, at a given RPM. Multiple such measurements are made at each of a number of rotational speeds. The frequency of harmonic, k, varies with rotational speed, and thus relationship 246 may be characterized as a set of amplitude and phase relationships over a range of frequencies for a given harmonic, k,.

[0030] Thus, relationship 246 can be equated to a transfer function between two locations, e.g., an ear location (e.g., microphone 140) and a remote location (e.g., microphone 240), where the transfer function is a phase and magnitude relationship over a range of frequencies, such as from "input" to "output." Thus, a filter with an associated transfer function may account for the remote location of microphone 240, e.g., as if microphone 240 were located at the ear, such that the filter "projects" the microphone's signal to the ear location.

[0031] In some embodiments, such a transfer function may be thought of as the actual transfer function of acoustic energy as it arrives at a first location and travels to a second location. Such may be true for audio coming from a given source and under certain operating conditions. For example, a first harmonic (k=1) of 100 Hz coming from an engine may create a particular relationship 246, while a second harmonic (k=2) of 100 Hz may create a different relationship. Similarly, a 100 Hz tone coming from a loudspeaker in a vehicle may create a significantly different relationship because the source location of the tone and its transmission to the two locations is significantly different than the first engine harmonic of 100 Hz.

[0032] In various embodiments, multiple measurements may be taken for each harmonic, k, and at each rotational speed, and the average phase and amplitude relationship may be used for the given harmonic and rotational speed. In addition, as will be shown in more detail below, the relationship 246 for a given harmonic and rotational speed may depend on further parameters such as torque, load, window position, etc. In various embodiments, multiple measurements may be taken at different torques (or other variations in operating parameters), and the average phase and amplitude relationship may be used for the given harmonic and rotational speed under "average" torque operating conditions.

[0033] For example, in some embodiments, multiple measurements may be taken over a range of positive torque conditions, and an average of these is used when the vehicle is operated at positive torque. Similarly, in some embodiments, multiple measurements may be taken over a range of negative torque conditions, and an average of these is used when the vehicle is operated at negative torque. In addition, some embodiments may include multiple measurements taken over a range of substantially neutral torque conditions, and an average of these is used when the vehicle is operated at substantially neutral torque.

[0034] 3 is an exemplary tuning system 300 that is a temporary configuration for taking measurements to characterize various harmonic relationships 246 at various rotational speeds. Various embodiments of sound cancellation systems consistent with those described herein do not include microphones 140 located at the occupant's ears. Various sound cancellation systems herein include one or more projection filters, each of which applies a transfer function to a far-microphone signal (e.g., from microphone 240) in order to estimate the signal that an ear microphone (e.g., microphone 140) would produce if it were present.

[0035] Some embodiments may include multiple remote microphones 240, such as for multiple locations in a vehicle. Additionally, some embodiments of a tuning system similar to that of FIG. 3 may include multiple remote microphones 240 and may also include multiple ear microphones 140, such as on either side of an occupant's head and / or for multiple occupants. Thus, R k and E k may each be a column vector whose number of elements is the number of remote microphones and the number of ear microphones, respectively. In such an embodiment, the transfer function of the projection filter (a filter that receives the remote microphone signals and estimates the ear microphone signals) may be a matrix. In other embodiments, such a transfer function may be considered to be multiple projection filters, each "projecting" the location of a remote microphone onto the location of an ear microphone.

[0036] Many of the quantities discussed herein are related to rotational speed, with each harmonic having a particular frequency at a given rotational speed. Thus, for a given harmonic, the various quantities described depend on the rotational speed and therefore the frequency. For the sake of brevity, the further discussion below omits notation of frequency and / or rotational speed, e.g., "x(f)" and / or "x(RPM)". Furthermore, the harmonic subscript, k, may also be omitted in various cases, but it should be understood by those skilled in the art that each relationship and / or projection filter transfer function is for a particular harmonic over a range of frequencies.

[0037] When multiple relationships 246 for a particular harmonic are measured across a range of rotational speeds, the job of the projection filter as described herein is to determine the projection filter transfer function, W, as in the relationship of Eq. RE The far microphone signal (R) is estimated from the ear microphone signal via

number

number

[0038] Projection filter transfer function, W RE is the E from a tuned system similar to that in Figure 3. k and R k Given the measured data, the projection filter transfer function, W RE may be determined according to Equation 3.

number

[0039] According to various embodiments, the projection filter transfer function, W RE is applied in concert with an exemplary sound cancellation system 400 as illustrated in FIG. 4. The sound cancellation system 400 includes a projection filter 440 that receives the error signal 242 from the microphone 240 and filters it to generate an estimated error signal 442. The estimated error signal 442 is thereby an estimate of the error signal that would have been provided by an ear microphone, e.g., it is an estimate of the error signal 142 that would have been provided by the microphone 140, with reference to FIG. 1, where the microphone 140 is an ear microphone. As mentioned above, various embodiments may include multiple microphones 240 and multiple ear microphones may be estimated, and thus the projection filter 440 may be a multi-input and / or multi-output filter, e.g., a W RE may be a matrix or a vector.

[0040] Continuing to refer to FIG. 4, as described above, driver 130 generates a cancellation audio signal 132, which is also picked up by microphone 240. As further described above, the transformation W RE is specific to a particular noise source, e.g., an engine, and to the particular harmonics from the noise source. Thus, the projection filter transfer function, W RE is inaccurate with respect to the cancellation audio signal 132 and, for example, does not accurately estimate the cancellation audio signal 132 at the location of the passenger's ear. Thus, any components of the error signal 242 that come from the cancellation audio signal 132 at the microphone 240 are essentially corrupted signals. Thus, various embodiments may include one or more additional filters to correct for such components.

[0041] As discussed above, the cancellation signal 122 is a driver signal, D, that drives the transducer 130 to produce the cancellation audio signal 132. Thus, the content in the error signal 242 that is the result of the cancellation audio signal 132 may be described by expression (4).

number

[0042] 5 illustrates another exemplary sound cancellation system 500 similar to sound cancellation system 400, but including an additional filter to compensate for the "corruption" in the estimated error signal 442 caused by the cancellation audio signal 132 being processed by the projection filter 440. Simply put, the sound cancellation system 500 subtracts the "corruption" components described above in (4) from the estimated error signal 442 to generate a signal representing an estimate of the undesired signal at the occupant's ear without the effect of the cancellation audio signal 132. The sound cancellation system 500 also generates a signal that is an estimate of the residual undesired signal at the occupant's ear in addition to the effect of the cancellation audio signal 132 at the occupant's ear, which is the estimated error signal that the adaptation module 150 can use to update the cancellation filter 120.

[0043] 5, sound cancellation system 500 includes a first correction filter 510 that receives driver signal 122 and outputs an estimate of the "corrupted" portion of estimated error signal 442 (e.g., see (4) above), which is then subtracted from estimated error signal 442 by combiner 520. Sound cancellation system 500 also includes a second correction filter 530 that receives driver signal 122 and outputs an estimate of the actual contribution of cancellation audio signal 132 at the passenger's ears, which is then summed by combiner 540 to generate a corrected estimated error signal 542. In various embodiments, second correction filter 530 is a filter ... (e.g., see (4) above), which is the secondary path transfer function from the driver to the location of the passenger's ears (or an estimate thereof), as described above. DE applies.

[0044] Figure 6 illustrates an exemplary sound cancellation system 600, which is a simplification of the sound cancellation system 500 of Figure 5. The sound cancellation system 600 combines the first and second correction filters 510, 530 with a single correction filter 610 that receives the driver signal 122 and outputs a combined correction signal 612 that is added to the estimated error signal 442 via a combiner 620 to generate a corrected estimated error signal 542.

[0045] In various embodiments, the transfer function of the compensation filter 610 may be inconsequential, such as when the "corruption" components described in (4) above are substantially equivalent to the actual contributions of the cancellation audio signal 132 at the passenger's ears. In such cases, the compensation filter 610 may be omitted and the system may be simplified back to substantially that shown in FIG.

[0046] As discussed above, any of the various relationships 246 for a particular harmonic may vary based on any one or more of engine rotational speed (RPM), transmission RPM, engine output torque (τ), transmission output torque, throttle position, manifold vacuum, engine spark timing / rate, rate of change of engine and / or transmission RPM (e.g., delta-RPM, ΔRPM), load / loading and distribution of same, acceleration (transfers load to rear suspension), braking / deceleration (transfers load to front suspension), turning / cornering acceleration (transfers load from side to side), and / or suspension control and / or damper stiffness (e.g., hydraulic, pneumatic, electronically controlled suspension components).

[0047] Thus, in various embodiments, different transfer functions of the projection filter, W RE , and / or different transfer functions of the correction filters, W DE may be selected based on variations in any of the above operating parameters of the vehicle. For simplicity, in the following description, examples are presented with respect to selecting different transfer functions based on torque, τ, but it will be understood that any of the above or other operating parameters may serve as the basis for selecting, modifying, retrieving, or storing the transfer functions of any of the projection filter and / or correction filter.

[0048] FIG. 7 illustrates another example sound cancellation system 700 that adjusts the transfer functions of one or more of the projection filter 740 and / or the correction filter 710 based on, for example, an indication of torque, τ, from a torque sensor 730 to generate a (corrected) estimated error signal 742.

[0049] In various embodiments, the filter transfer function for a particular torque may be determined by measuring (e.g., via tuning system 300) over multiple runs recorded at that particular torque, and / or the projected filter transfer function for a particular torque, W REcan be estimated by evaluating the expected value of the recordings made at that particular torque. In various embodiments, a reduced number of filter transfer functions, W, can be calculated by measuring or determining one each for positive and negative torque. RE , W DE may be used (e.g., to reduce storage requirements). For example, the mechanism of harmonic sound transmission into the vehicle cabin may be significantly different when the drivetrain is under positive output torque versus negative output torque. In various embodiments, multiple levels of positive torque, negative torque, and possibly neutral torque (e.g., coasting) may each have a determined projection. Thus, various embodiments may use multiple filter transfer functions W RE , W DE may be stored, each of which is available to be selected and applied based on current vehicle operating conditions, such as torque, but including any number of additional operating conditions, in various embodiments, as variously described above. In some embodiments, the system or method may interpolate for operating conditions between those for which the record and filter transfer functions were determined. For example, in at least one embodiment, the system may store stored filter transfer functions W associated with torque values ​​of -50 Newton meters (Nm), 0 N-m, and 200 N-m. RE , W DE and when the current torque is 100 N-m, the filter transfer function may be interpolated between the transfer functions stored for, for example, 0 N-m and 200 N-m.

[0050] In addition to vehicle powertrain operation and loads as discussed above, the various harmonics and transfer functions 160 (secondary paths) relationships 246 from the transducer 130 to the occupant's ears 244 may change as the acoustics of the environment (e.g., vehicle cabin) change. Thus, various embodiments of the sound cancellation systems or algorithms herein may dynamically change (adjust, select) the projection filter transfer function and / or the correction filter transfer function based on changes in the vehicle cabin acoustics.

[0051] In various embodiments, changes in cabin acoustics may be communicated via digital control signals and may include, for example, window open / closed status (which windows and how much), sunroof open / closed status (and how much), hatch door open / closed status, rear seat status (folded, stowed, etc.), cargo / load, and occupancy such as how many passengers are in the passenger compartment, the seats therein, and their sizes, as well as others. For example, occupancy may be estimated by data from airbag occupant sensors in the seats. In some embodiments, camera, video, and / or facial recognition systems may also provide information regarding the cabin status.

[0052] Although the examples herein have been described with respect to canceling or reducing harmonics of a rotating device, the example systems, methods, and program codes may be beneficially applied to improving or otherwise modifying harmonic acoustic signals. In such examples, the cancellation filters described herein may be improvement filters configured and adapted to provide an improvement signal that causes a transducer to provide an improvement audio signal to modify the sound of one or more harmonics at an occupant's ear. A feedback sensor (remote microphone) may be "projected" to the location of the occupant's ear in a manner similar to the example systems and methods described above. Thus, in such examples, one or more of the projection filters and / or correction filters may be applied in a manner similar to the examples described herein to provide an estimated signal representative of the sound at the occupant's ear, and the improvement filter (or the otherwise cancellation filter) may be adapted to achieve a target sound of one or more harmonics.

[0053] In various embodiments, harmonic refinement, reduction, or cancellation may be performed for multiple passenger locations. For example, remote microphone 240 may be included to detect acoustic energy at more than one location, and multiple projection and correction filters may be stored for multiple passenger ear locations. In such embodiments, harmonic refinement, reduction, or cancellation may be performed for selected passenger locations depending on actual occupancy and / or user selection. For example, a rear seat passenger may be detected, and an example system herein may operate to reduce harmonics at the rear passenger's ear while reducing harmonics at the operator's ear (e.g., at the driver's seat). However, the system may disable harmonic reduction at the rear passenger's ear locations when no rear passenger is detected to be present and / or based on a user selection to disable harmonic reduction at the rear seat locations. Deactivation of harmonic reduction at one or more locations may enable better performance of harmonic reduction at other locations, so the system may minimize acoustic harmonic content in fewer locations.

[0054] Although examples herein have been described with respect to a vehicle environment, the exemplary systems, methods, and program code may be beneficially applied to canceling, improving, or otherwise modifying harmonic acoustic signals in other environments, such as industrial, manufacturing, factory, electrical production, or other environments that may involve rotating equipment that may generate undesirable acoustic harmonic noise.

[0055] The functionality or portions thereof, and various modifications thereof (hereinafter "functionality") described herein may be implemented at least in part via a computer program product (e.g., a computer program tangibly embodied in an information carrier, such as one or more non-transitory machine-readable media or storage devices, for execution by or to control the operation of one or more data processing apparatus, e.g., a programmable processor, computer, multiple computers, and / or programmable logic components).

[0056] The computer program can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer, or on multiple computers at one site, or distributed across multiple sites and interconnected by a network.

[0057] The operations associated with implementing all or a portion of the functionality may be performed by one or more programmable processors executing one or more computer programs to perform the functions of the calibration process. All or a portion of the functionality may be implemented as special purpose logic circuitry, such as an FPGA and / or an ASIC (application-specific integrated circuit).

[0058] Processors suitable for executing a computer program also include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Typically, a processor will receive instructions and data from a read-only memory, a random access memory, or both. Elements of a computer include a processor for executing instructions and one or more memory devices for storing instructions and data.

[0059] Although certain inventive examples have been described and illustrated herein, those skilled in the art will readily conceive of various other means and / or structures for performing the functions and / or obtaining the results and / or advantages of one or more of the inventions described herein, and each of such modifications and / or variations can be considered to be within the scope of the inventive examples described herein. More generally, those skilled in the art will readily appreciate that all of the parameters, dimensions, materials, and configurations described herein are exemplary, and that the actual parameters, dimensions, materials, and / or configurations will depend on the particular application or applications for which the teachings of the present invention are used. Those skilled in the art will recognize or be able to ascertain through routine experimentation many equivalents to the specific inventive examples described in the present invention. Thus, it is to be understood that the foregoing examples have been presented by way of example only, and that within the scope of the appended claims and equivalents thereof, the inventive examples can be practiced otherwise than as specifically described and claimed. The inventive examples of the present disclosure are directed to each individual feature, system, article, material, and / or method described herein. Furthermore, any combination of two or more such features, systems, articles, materials, and / or methods is within the scope of the invention, if such features, systems, articles, materials, and / or methods are not mutually inconsistent. [Explanation of symbols]

[0060] 100 Noise Cancellation System 110 Signal source 112 Reference Signal 114 Sensors 120 Cancellation Filter 122 Cancellation Signal 130 Driver, Transducer 132 Cancellation Audio Signal 140 Microphone 142 Error signal 150 Adaptation Module 160 Transfer Function 200 Sound Cancellation System 240 Remote Microphone 240 Microphone 242 Error signal 244 Ear 246 Relationships 300 Tuning System 310 Sine wave source 320 harmonics 330 Mixer 400 Sound Cancellation System 440 Projection Filter 442 Estimation error signal 500 Sound Cancellation System 510 First correction filter 510 First correction filter 520 Combiner 530 Second correction filter 540 Combiner 542 Estimation error signal 600 Sound Cancellation System 610 Correction Filter 612 Correction Signal 620 Combiner 700 Sound Cancellation System 710 Correction Filter 730 Torque Sensor 740 Projection Filter 742 (corrected) estimated error signal

Claims

1. 1. A sound cancellation system comprising: a transducer configured to receive the cancellation signal and generate a cancellation audio signal within the vehicle; a microphone configured to provide an error signal representative of acoustic energy at a first location within the vehicle; a projection filter configured to filter the error signal to provide an estimated error signal that is an estimate of the error signal that would have been provided if the microphone were located at a second location within the vehicle, the projection filter being selected based on a state of the vehicle; and an adaptation module for adjusting the cancellation signal based on the estimated error signal; the condition of the vehicle is one of a powertrain operating condition or a passenger compartment acoustic condition; the powertrain operating conditions being one or more of manifold vacuum, load transfer to rear suspension, load transfer to front suspension, turning / cornering acceleration, and damper stiffness; The vehicle cabin acoustic condition is one or more of an occupancy rate estimated by an airbag sensor or a facial recognition. Sound cancellation system.

2. The sound cancellation system of claim 1 , wherein the conditions of the vehicle further include one or more of rotational speed and torque.

3. 2. The sound cancellation system of claim 1, further comprising a correction filter configured to filter the cancellation signal to provide a correction signal that is combined with the estimated error signal to provide a corrected estimated error signal, the sound cancellation system configured to adjust the cancellation signal based on the corrected estimated error signal.

4. The sound cancellation system of claim 3 , wherein the corrective filter is selected based on the condition of the vehicle.

5. 10. The sound cancellation system of claim 1, further comprising a cancellation filter that receives a harmonic signal and provides the cancellation signal, the sound cancellation system configured to adjust the cancellation signal by adjusting the cancellation filter.

6. 1. A sound cancellation system comprising: a cancellation filter for receiving a harmonic signal associated with the rotating device and providing a cancellation signal; a transducer coupled to the cancellation filter for receiving the cancellation signal and generating a cancellation audio signal in an environment; a microphone configured to provide an error signal representative of acoustic energy at a first location within the environment; a projection filter configured to filter the error signal to provide an estimated error signal that is an estimate of the error signal that would have been provided if the microphone were positioned at a second location in the environment; and an adaptation module for adjusting the cancellation signal based on the estimated error signal; the projection filter is selected based on an operating condition of the rotating device or an acoustic condition of the environment; the operating condition of the rotating device is one or more of manifold vacuum, load transfer to rear suspension, load transfer to front suspension, turning / cornering acceleration, and damper stiffness; the acoustic condition of the environment is one or more of an occupancy estimated by an airbag sensor or a facial recognition; Sound cancellation system.

7. 1. A method of cancelling sound, comprising: converting the cancellation signal into a cancellation audio signal within the vehicle cabin; detecting an error signal at a first location within the vehicle cabin with a feedback sensor, the error signal being indicative of acoustic energy at the first location; filtering the error signal through a projection filter selected based on a state of the vehicle to provide an estimated error signal that is an estimate of the error signal that would have been provided if the feedback sensor were located at a second location within the vehicle cabin; and adjusting the cancellation signal based on the estimated error signal; the condition of the vehicle is one of a powertrain operating condition or an acoustic condition of the passenger compartment; the powertrain operating conditions being one or more of manifold vacuum, load transfer to rear suspension, load transfer to front suspension, turning / cornering acceleration, and damper stiffness; The acoustic condition of the vehicle cabin is one or more of an occupancy estimated by an airbag sensor or a facial recognition. method.

8. The method of claim 7 , wherein the conditions of the vehicle further include one or more of rotational speed and torque.

9. 8. The method of claim 7, further comprising filtering the cancellation signal through a correction filter to provide a correction signal, combining the correction signal with the estimated error signal to provide a corrected estimated error signal, and adjusting the cancellation signal based on the corrected estimated error signal.

10. The method of claim 9 , wherein the correction filter is selected based on the condition of the vehicle.

11. 8. The method of claim 7, further comprising filtering a harmonic signal through a cancellation filter to provide the cancellation signal; and adjusting the cancellation signal by adjusting the cancellation filter.

12. A method for adjusting harmonic sounds, comprising: filtering harmonic signals associated with the rotating device to provide a cancellation signal; converting said cancellation signal into a cancellation audio signal in an environment; receiving an error signal representative of acoustic energy at a first location within the environment; filtering the error signal to provide an estimated error signal that is an estimate of the error signal that would have been provided if the error signal had been received at a second location within the environment; adjusting the cancellation signal based on the estimated error signal; filtering the error signal to provide an estimated error signal based on an operating condition of the rotating device or an acoustic condition of the environment; the operating condition of the rotating device is one or more of manifold vacuum, load transfer to rear suspension, load transfer to front suspension, turning / cornering acceleration, and damper stiffness; the acoustic condition of the environment is one or more of an occupancy estimated by an airbag sensor or a facial recognition; method.

13. A non-transitory computer-readable medium having instructions recorded thereon, the instructions, when executed by one or more processors, causing the one or more processors to: providing a cancellation signal that is converted into an acoustic signal in the environment; receiving an error signal from a feedback sensor at a first location in the environment, the error signal representing acoustic energy at the first location; filtering the error signal with a projection filter to provide an estimated error signal that is an estimate of the error signal that would have been provided if the feedback sensor were located at a second location in the environment, a transfer function of the projection filter being selected based on an operating condition of a rotating device; adjusting the cancellation signal based on the estimated error signal; the operating condition is one of a vehicle powertrain operating condition or a vehicle cabin acoustic condition; the powertrain operating conditions being one or more of manifold vacuum, load transfer to rear suspension, load transfer to front suspension, turning / cornering acceleration, and damper stiffness; 11. A non-transitory computer-readable medium for carrying out a method, wherein the acoustic condition of a vehicle cabin is one or more of an occupancy estimated by an airbag sensor or facial recognition.

14. The computer-readable medium of claim 13 , wherein the operating conditions further include one or more of rotational speed and torque.

15. 14. The computer-readable medium of claim 13, further comprising filtering the cancellation signal through a correction filter to provide a correction signal, combining the correction signal with the estimated error signal to provide a corrected estimated error signal, and adjusting the cancellation signal based on the corrected estimated error signal.

16. The computer-readable medium of claim 13 , further comprising filtering a harmonic signal associated with the rotating device to provide the cancellation signal.

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