Patent Description:
Disclosed herein are methods and systems relating to performing multiple sound localizations to improve internal sound synthesis.

Vehicles include components that generate noise that is typically audible to drivers or other passengers. For example, a driver may hear noise generated by both an engine and an exhaust system of the vehicle. However, many newly developed engines generate low engine sounds. In particular, turbocharged engines produce very little engine sound. Engine noise may be absent in hybrid vehicles when running on electric power, and electric vehicles may lack engine noise entirely. This absence of engine noise may be unexpected to a driver and may make the driver feel that the engine is not powerful enough. Therefore, a vehicle audio system may generate synthetic noise that represents typical or expected noise generated while operating the vehicle.

<CIT> discusses a control unit which monitors an operating state of a vehicle by an accelerator depression amount sensor and the like, reads a parameter corresponding to the operating state from a parameter memory, gain control amplifiers, and sound image localization control to provide a vehicle interior sound field control device of generating a fresh engine sound.

<CIT> discusses a sound output apparatus for a vehicle including a sound input device, a sound signal generation section, a sound output device, a road-information acquisition section, and a specified-direction determination section. The sound input device collects sounds outside of the vehicle. The sound signal generation section generates an output signal based on the sounds outside of the vehicle collected. The sound output device outputs a sound to a vehicle interior of the vehicle based on the output signal generated. The road-information acquisition section acquires road information in proximity of the vehicle. The specified-direction determination section determines a specified direction which is previously associated with the road information.

<CIT> discusses reproducing an audio signal high frequency component controlled in terms of directivity, or an audio signal high frequency component compensated in terms of frequency characteristic or controlled in terms of directivity is reproduced, such that the reflected sound comes from a direction in which the high frequency component is intended to be localized.

The present application provides a system for synthesizing engine sound in a cabin of a vehicle as defined in independent claim <NUM>.

The present invention further provides a method for synthesizing engine sound in a cabin of a vehicle as defined in independent claim <NUM>.

Further advantageous aspects of the present invention are defined in the dependent claims.

The embodiments of the present disclosure are pointed out with particularity in the appended claims. However, other features of the various embodiments will become more apparent and will be best understood by referring to the following detailed description in conjunction with the accompanying drawings in which:.

As required, detailed embodiments of the present embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the embodiments that may be embodied in various and alternative forms.

With reference to <FIG>, a vehicle system <NUM> for synthesizing engine sound is illustrated in accordance with one or more embodiments. The vehicle system <NUM> is depicted within a vehicle <NUM>. The vehicle <NUM> includes a powertrain <NUM> with an internal combustion engine (ICE) <NUM> and/or an electric motor <NUM>. The vehicle system <NUM> also includes a controller <NUM>, a plurality of loudspeakers <NUM>, and, in certain embodiments, at least one microphone <NUM>.

A vehicle occupant may expect to hear noise from the powertrain <NUM> within an interior cabin or passenger compartment <NUM> of the vehicle <NUM> during certain driving modes or maneuvers. Such powertrain noise may be reduced, absent, or otherwise unsatisfying in new vehicle architectures and driving modes. Accordingly, the controller <NUM> may be configured to generate synthesized engine noise. As input to the engine noise generation, the controller <NUM> may be configured to communicate with one or more other vehicle controllers (not shown) to monitor various vehicle components and systems, such as the powertrain <NUM> under current driving conditions. In an example, the controller <NUM> may monitor engine revolutions per minute (RPM) as an input to the generation of synthesized engine noise and may use the RPM input to identify what frequencies to generate to simulate engine noise. The controller <NUM> may also adjust the synthesized engine noise signal by providing audible feedback of the vehicle's driving dynamics (e.g., acceleration, cruising, deceleration, reversing, startup, shutdown). This synthesized engine noise may then be provided to the loudspeakers <NUM> to be projected within the passenger compartment <NUM>. The synthesized engine noise may combine with the actual engine sound (if present) to produce the total engine sound heard by the driver. This total engine sound combines with background noise in the passenger compartment to form the soundscape experienced by the vehicle occupants.

The controller <NUM> may communicate with other vehicle systems and controllers via one or more vehicle networks by wired or wireless communication. The vehicle network may include a plurality of channels for communication. One channel of the vehicle network may be a serial bus such as a Controller Area Network (CAN). One of the channels of the vehicle network may include an Ethernet network defined by Institute of Electrical and Electronics Engineers (IEEE) <NUM> family of standards. Additional channels of the vehicle network may include discrete connections between modules and may include power signals. Different signals may be transferred over different channels of the vehicle network. For example, video signals may be transferred over a high-speed channel (e.g., Ethernet) while guiding signals may be transferred over CAN or discrete signals. The vehicle network may include any hardware and software components that aid in transferring signals and data between modules and controllers.

Although the controller <NUM> is shown as a single controller, it may contain multiple controllers, or it may be embodied as software code within one or more other controllers. The controller <NUM> generally includes any number of microprocessors, ASICs, ICs, memory (e.g., FLASH, ROM, RAM, EPROM and/or EEPROM) and software code to interact with one another to perform a series of operations. The controller <NUM> may also include or have access to predetermined data, or look-up tables, that are stored within the memory, according to one or more embodiments. In an example, the controller <NUM> may maintain a look-up table of frequencies to generate according to engine RPM.

<FIG> illustrates an example signal flow <NUM> including a single sound synthesizer <NUM> and a single localization filter set <NUM> according to an example not forming part of the claimed invention. In an example, the sound synthesizer <NUM> and localization filter set <NUM> may be implemented using the circuitry and/or software of the controller <NUM>.

The sound synthesizer <NUM> may be configured to receive inputs from the powertrain <NUM> and other vehicle <NUM> systems, and use those inputs to generate synthesized engine noise audio signals. In an example, the inputs may be one or more of engine RPM, a signal derived from a pressure or vibration sensor that is mounted in proximity to the powertrain <NUM> and/or emissions system, and/or a signal that represents current vibroacoustic emissions of the powertrain <NUM>. In an example, the sound synthesizer <NUM> processes these signals to generate individual engine orders that may then be individually filtered, equalized, and mixed to be combined as the synthesized engine noise output. In some examples, actual engine noise may additionally or alternately be filtered and provided to the mixer to create or augment the characteristics of the synthesized engine noise.

The localization filter set <NUM> may be configured to receive the synthesized engine noise audio signal from the sound synthesizer <NUM> and generate a sound image that appears to emanate from a predefined location of the vehicle <NUM>. To perform the localization, the localization filter set <NUM> may utilize phase and delay operations to focus sound on a subarea when the outputs of the localization filter set <NUM> are applied to the loudspeakers <NUM>. In an example, the localization filter set <NUM> may be formed according to an offline process by which acoustic measurements of the vehicle cabin or passenger compartment <NUM> are used to calculate filter coefficients. A sound signal may then be applied to the localization filter set <NUM> such that the filters of the localization filter set <NUM> use the learned filter coefficients to create a set of outputs that when applied to the loudspeakers <NUM> produce an image of the sounds at the correct location. In an example, the localization filter set <NUM> may be used to create an illusion to the listeners that synthetic engine sound is emanating from the engine compartment. In another example, the localization filter set <NUM> may be used to create an illusion that synthetic engine sound is emanating from the vehicle exhaust.

As the signal flow <NUM> utilizes a single sound synthesizer <NUM> and a single localization filter set <NUM>, all the sound, regardless of engine order and frequency, is focused on one area. However, it would be preferable to have multiple sound images that can simulate multiple sound sources of vehicles <NUM> such as both engine intake and engine exhaust.

<FIG> illustrates an example signal flow <NUM> including multiple sound synthesizers <NUM>-A and <NUM>-B (collectively <NUM>) and multiple localization filter sets <NUM>-A and <NUM>-B (collectively <NUM>) according to an example not forming part of the claimed invention.

As shown, the signal flow <NUM> includes two sound synthesizers <NUM>, each connected to a respective localization filter set <NUM>. More specifically, a first sound synthesizer <NUM>-A is connected to a first localization filter set <NUM>-A, while a second sound synthesizer <NUM>-B is connected to a second localization filter set <NUM>-B. The outputs of the first localization filter set <NUM>-A and the second localization filter set <NUM>-B are combined by a mixer <NUM>, where the combined outputs from the mixer <NUM> are reproduced via the loudspeakers <NUM>.

Using the example signal flow <NUM>, each sound synthesizer <NUM> may represent a virtual sound source such as an engine intake or an engine exhaust, and each sound synthesizer <NUM> may utilize its own localization filter set <NUM> to provide the simulated sounds with a different sound image. While only two sound synthesizer <NUM> - localization filter set <NUM> pairs are illustrated in the signal flow <NUM>, this design could be extended to have further pairs of sound synthesizers <NUM> with corresponding localization filter sets <NUM>. Nevertheless, in a system of the form shown in the signal flow <NUM>, there are the same number of sound synthesizers <NUM> and localization filter sets <NUM> in the signal flow <NUM>.

<FIG> illustrates an example signal flow <NUM> using oscillator grouping to utilize a single sound synthesizer <NUM> with multiple localization filter sets <NUM>-A and <NUM>-B (collectively <NUM>) in accordance with the claimed invention. While oscillators are used in many examples herein, it should be noted that the sound synthesizer <NUM> may be any type of engine noise synthesizer that generates multiple signals that can be combined together, e.g., wavefile-based and/or oscillator based. As shown in the signal flow <NUM>, instead of using multiple sound synthesizers <NUM>, oscillator signals of the single sound synthesizer <NUM> may be grouped into multiple sets and sent to different localization filter sets <NUM>.

The sound synthesizer <NUM> is configured to generate a plurality of engine orders (e.g., sixteen in one example, but more or fewer are possible). These orders may include a fundamental frequency as well as one or more higher orders. Using different combinations of these orders, multiple outputs from the sound synthesizer <NUM> may be provided. For instance, to generate an output for use in simulating an engine, a set of orders may be created using more lower order content and less higher order content. As one possibility, to simulate a four-cylinder engine a set of orders may be created that includes second and fourth orders as dominant, while to simulate a six-cylinder engine a set of orders may be created that includes third and sixth orders as dominant. Or, to generate an output for use in simulating an air intake, more higher orders and fewer (or a lower mix level) of lower orders may be included.

As shown, the sound synthesizer <NUM> may include one or more sets of oscillator gain levels <NUM> that may be used to adjust the levels of the orders generated by the oscillators of the sound synthesizer <NUM>. These levels, as adjusted, may then be applied to output mixers <NUM> for each output of the sound synthesizer <NUM>. To generate two outputs from the sound synthesizer <NUM>, the sound synthesizer <NUM> includes a two channel mixer <NUM>, where a first channel of the mixer mixes the outputs of the orders in accordance with the oscillator gain levels <NUM> for the first output, while the second channel of the mixer mixes the outputs of the orders in accordance with oscillator gain levels <NUM> for the second output.

While multiple virtual sounds may be created using a single sound synthesizer <NUM>, similar to as shown in the signal flow <NUM>, multiple localization filter sets <NUM> may be used to provide location of the multiple sound images. Each output of the sound synthesizer <NUM> is provided to its own localization filter set <NUM> to allow for the localization of the outputs to be performed separately. As with the signal flow <NUM>, the outputs of the multiple localization filter sets <NUM> are combined using the mixer <NUM> and amplified to drive the loudspeakers <NUM>.

Thus, the sound synthesizer <NUM> may be used to create both a front sound stage and a rear sound stage, while using a single set of engine order oscillators. Notably, the concept shown in the signal flow <NUM> of using a sound synthesizer <NUM> to generate multiple outputs saves memory and other resources of the controller <NUM>, as compared to the approach shown in the signal flow <NUM> of using a different sound synthesizer <NUM> for each output.

<FIG> illustrates an example signal flow <NUM> using multiple synthesizer filters <NUM>-A and <NUM>-B (collectively <NUM>) to utilize a single sound synthesizer <NUM> with multiple localization filter sets <NUM>-A and <NUM>-B (collectively <NUM>) according to an example not forming part of the claimed invention. Similar to the signal flows <NUM> and <NUM> discussed in detail above, in the signal flow <NUM> multiple localization filter sets <NUM> may be used to generate multiple sound images from multiple outputs of the sound synthesizer <NUM>.

However, as compared to the multiple sets of engine order oscillators and mixed outputs provided in the signal flow <NUM>, each output of the sound synthesizer <NUM> in the signal flow <NUM> is generated by performing different filtering of a monaural output of the sound synthesizer <NUM>. In an example, the synthesizer filter <NUM>-A may be a high-pass filter applied to the output of the sound synthesizer <NUM> to generate a front vehicle soundstage, and the synthesizer filter <NUM>-B may be a low-pass filter applied to the same output of the sound synthesizer <NUM> to generate a rear vehicle soundstage. The high-pass filter may be used for the front soundstage to include more of the higher engine orders consistent with an engine intake, while the low-pass filter may be used for the rear soundstage to include more of the lower engine orders consistent with an engine exhaust.

It should be noted that this is but one example, and the monaural output of the sound synthesizer <NUM> may be applied to more or different synthesizer filters <NUM> including, but not limited to, high pass filters, low pass filters, band pass filters, notch filters, combinations of filters, complex equalizations, and so on.

Thus, similar to as shown in the signal flow <NUM>, using a sound synthesizer <NUM> to generate multiple outputs via the synthesizer filters <NUM> saves memory and other resources of the controller <NUM> as compared to the requirements of the approach shown in the signal flow <NUM> of using a different sound synthesizer <NUM> to produce each simulated engine sound output.

<FIG> illustrates an example process <NUM> for using a sound synthesizer <NUM> with multiple localization filter sets <NUM>. In an example, the process <NUM> may be performed using the vehicle system <NUM> performing according to the signal flows <NUM> or <NUM> discussed in detail above.

At operation <NUM>, the controller <NUM> receives engine data. In an example, the controller <NUM> receive inputs from the powertrain <NUM> and other vehicle <NUM> systems and uses those inputs to generate a synthesized engine noise audio signal. These inputs may include one or more of engine RPM, a signal derived from a pressure or vibration sensor that is mounted in proximity to the powertrain <NUM> and/or emissions system, and/or a signal that represents current vibroacoustic emissions of the powertrain <NUM>.

At operation <NUM>, the controller <NUM> creates engine orders using the engine data. In an example, a sound synthesizer <NUM> of the controller <NUM> processes the signals received at operation <NUM> to generate individual engine orders that may then be individually filtered, equalized, and mixed to be combined as the synthesized engine noise output. In some examples, actual engine noise may additionally or alternately be filtered and provided to the mixer to create or augment the characteristics of the synthesized engine noise.

At operation <NUM>, the controller <NUM> generates multiple outputs using the engine orders. In an example, as shown in the signal flow <NUM>, the sound synthesizer <NUM> may include one or more sets of oscillator gain levels <NUM> that may be used to adjust the levels of the orders generated by the oscillators of the sound synthesizer <NUM>. These levels, as adjusted, may then be applied to output mixers <NUM> for each output of the sound synthesizer <NUM>. In another example, as shown in the signal flow <NUM>, each output of the sound synthesizer <NUM> in the signal flow <NUM> is generated by different filtering of a monaural output of the sound synthesizer <NUM> using various synthesizer filters <NUM>.

At operation <NUM>, the controller <NUM> applies each of the outputs of the sound synthesizer <NUM> to a localization filter set <NUM>. In an example, each output may be applied to a different localization filter set <NUM> to cause the output to be provided at a different perceived location within the vehicle cabin or passenger compartment <NUM>.

At operation <NUM>, the controller <NUM> uses the outputs of the localization filter sets <NUM> to generate sound images in the vehicle cabin or passenger compartment <NUM>. In an example, the outputs of the localization filter sets <NUM> may be provided to a mixer <NUM>, which in turn created outputs for each loudspeaker <NUM> to be amplified and used to drive the loudspeakers <NUM>. Thus, a sound synthesizer <NUM> may be used to generate multiple sound images within the vehicle cabin or passenger compartment <NUM>, thereby saving memory and other resources of the controller <NUM> as compared to using a different sound synthesizer <NUM> to produce each sound image. After operation <NUM>, the process <NUM> ends.

The embodiments of the present disclosure generally provide for a plurality of circuits or other electrical devices. It is recognized that any circuit or other electrical device disclosed herein may include any number of microcontrollers, a graphics processor unit (GPU), integrated circuits, memory devices (e.g., FLASH, random access memory (RAM), read only memory (ROM), electrically programmable read only memory (EPROM), electrically erasable programmable read only memory (EEPROM), or other suitable variants thereof) and software which co-act with one another to perform operation(s) disclosed herein. In addition, any one or more of the electrical devices may be configured to execute a computer-program that is embodied in a non-transitory computer readable medium programmed to perform any number of the functions as disclosed.

Claim 1:
A system (<NUM>) for synthesizing engine sound in a cabin of a vehicle (<NUM>) comprising:
a sound synthesizer (<NUM>) configured to generate a synthesized engine noise audio signal output including a plurality of engine orders;
a synthesizer output mixer (<NUM>), including a first channel configured to mix the output of the sound synthesizer in accordance with first settings to provide a first channel output, and a second channel configured to mix the output of the sound synthesizer in accordance with second settings to provide a second channel output;
first and second localization filter sets (<NUM>-A, <NUM>-B), each configured to utilize phase and delay operations to focus sound on a respective subarea when outputs of the respective first and second localization filter sets are applied to loudspeakers (<NUM>),
the first localization filter set (<NUM>-A) configured to provide a first localized output to localize the first channel output as a first sound image at a first location, the second localization filter set (<NUM>-B) configured to provide a second localized output to localize the second channel output as a second sound image at a second location; and
a mixer (<NUM>) configured to combine the first localized output and the second localized output into loudspeaker outputs to be applied to the loudspeakers (<NUM>) to generate the first and second sound images;
wherein the sound synthesizer (<NUM>) is further configured to receive engine data from a powertrain of the vehicle to generate the synthesized engine noise audio signal, wherein the engine data includes one or more of engine revolutions per minute, RPM, a signal derived from a pressure or vibration sensor that is mounted in proximity to a powertrain of the vehicle or an emissions system of the vehicle, and a signal that represents current vibroacoustic emissions of the powertrain of the vehicle, and
wherein the sound synthesizer (<NUM>) is further configured to provide a plurality of separate outputs for each of the plurality of engine orders, the first settings include a first set of gain levels to be applied to each of the plurality of separate outputs to provide the first channel output, and the second settings include a second set of gain levels to be applied to each of the plurality of separate outputs to provide the second channel output.