Systems and methods for vehicle sound enhancement

1. A method for a vehicle, comprising:

acquiring, from a sensor configured to measure engine sounds of an engine of the vehicle, the measured engine sounds;

filtering the measured engine sound based on operating conditions of the engine to obtain an enhanced engine sound, including:

upmixing the measured engine sound into a plurality of channels for a given number of engine orders,

adjusting an order filter for each engine order of the given number of engine orders based on the operating conditions of the engine,

filtering each channel of the plurality of channels with the corresponding order filter and with a low-pass filter, and

mixing the filtered channels into a mono output comprising the enhanced engine sound; and

outputting, to a speaker positioned in a cabin of the vehicle, the enhanced engine sound.

2. The method of claim 1 , wherein adjusting the order filter for each engine order based on the operating conditions of the engine comprises:

adjusting a gain and a quality factor for each order filter based on measurements of revolutions per minute (RPM) and torque of the engine; and

adjusting a center frequency for each order filter based on the RPM.

3. The method of claim 1 , further comprising:

upmixing the mono output into a second plurality of channels; and

applying a separate delay to each channel of the second plurality of channels, wherein outputting the enhanced engine sound to the speaker comprises outputting the delayed channels to respective speakers in the vehicle.

4. A method for a vehicle, comprising:

acquiring a signal including harmonic content generated by an engine of the vehicle;

upmixing the signal into a plurality of channels for a given number of engine orders;

adjusting an order filter for each engine order of the given number of engine orders based on operating conditions of the engine;

filtering each channel of the plurality of channels with the corresponding order filter;

mixing the filtered channels into a mono output; and

outputting the mono output to at least one speaker in the vehicle,

wherein the order filter for each engine order corresponds with a multiple of a number of ignition events per revolution of a crankshaft of the engine of the vehicle.

5. The method of claim 4 , wherein acquiring the signal comprises acquiring the signal via an accelerometer mounted to the engine.

6. The method of claim 4 , wherein adjusting the order filter for each engine order based on the operating conditions of the engine comprises adjusting a gain and a quality factor for each order filter based on measurements of revolutions per minute (RPM) and torque of the engine, and further adjusting a center frequency for each order filter based on the RPM.

7. The method of claim 4 , further comprising filtering each channel with a low-pass filter prior to mixing the filtered channels into the mono output.

8. The method of claim 4 , further comprising adjusting a main gain of the mono output based on measurements of RPM and torque of the engine.

9. The method of claim 4 , further comprising upmixing the mono output into a second plurality of channels, and applying a separate delay to each channel of the second plurality of channels, wherein outputting the mono output to at least one speaker in the vehicle comprises outputting the delayed channels to respective speakers in the vehicle.

10. The method of claim 9 , further comprising running the delayed channels through a limiter to balance levels prior to outputting the delayed channels to the respective speakers in the vehicle.

11. The method of claim 4 , wherein the mono output is output to the at least one speaker in the vehicle within 10 milliseconds of acquiring the signal.

12. The method of claim 4 , further comprising mixing the mono signal into normal audio output to the at least one speaker.

13. A system for a vehicle, comprising:

a sensor configured to measure engine sounds of an engine of the vehicle;

a speaker positioned in a cabin of the vehicle; and

a computing system configured to:

acquire, from the sensor, the measured engine sounds;

apply filters to the measured engine sound based on operating conditions of the engine to obtain an enhanced engine sound, including to:

upmix the measured engine sound into a plurality of channels for a given number of engine orders, and

adjust an order filter for each engine order of the given number of engine orders based on the operating conditions of the engine,

wherein the order filter for each engine order corresponds with a multiple of a number of ignition events per revolution of a crankshaft of the engine of the vehicle; and

output, to the speaker, the enhanced engine sound.

14. The system of claim 13 , wherein the sensor comprises an accelerometer, and wherein the measured engine sound comprises vibrations generated by the engine.

15. The system of claim 13 , wherein, to apply the filters to the measured engine sound based on the operating conditions of the engine to obtain the enhanced engine sound, the computing system is further configured to:

filter each channel of the plurality of channels with the corresponding order filter; and

mix the filtered channels into a mono output comprising the enhanced engine sound.

16. The system of claim 15 , wherein, to adjust the order filter for each engine order based on the operating conditions of the engine, the computing system is further configured to:

adjust a gain and a quality factor for each order filter based on measurements of revolutions per minute (RPM) and torque of the engine; and

adjust a center frequency for each order filter based on the RPM.

17. The system of claim 15 , wherein the computing system is further configured to:

filter each channel with a low-pass filter prior to mixing the filtered channels into the mono output.

18. The system of claim 15 , further comprising a plurality of speakers including the speaker, wherein the computing system is further configured to:

upmix the mono output into a second plurality of channels; and

apply a separate delay to each channel of the second plurality of channels, wherein outputting the enhanced engine sound to the speaker comprises outputting the delayed channels to respective speakers in the vehicle.