Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Engine Simulator: produce realistic sounds from various engine parameters

github.com

Post reply on HN
Print view View original

21–30 of 31 posts

Re: Engine Simulator: produce realistic sounds from various engine parameters

#21

Post by userbinator »

tonmoy wrote: post #20
Cloudef wrote: post #9

Earlier quoted context omitted.

Could use convolution with recorded impulse response (IR) files to achieve realistic results for different exhausts.

Not sure how one would be able to obtain impulse response of the exhaust system

You can model it as a series of tubes of different diameters.

Look up "digital waveguide" for some more details. This technique is mostly used in speech synthesis, where it can make pretty realistic human-speech-like sounds by modelling the vocal tract, but there's no reason it can't be applied to a car exhaust system.

Re: Engine Simulator: produce realistic sounds from various engine parameters

#22

Post by Cloudef »

tonmoy wrote: post #20
Cloudef wrote: post #9

Earlier quoted context omitted.

Could use convolution with recorded impulse response (IR) files to achieve realistic results for different exhausts.

Not sure how one would be able to obtain impulse response of the exhaust system

Guitarists (or mixers) record IRs by playing a sine wave through their cab and recording that. The difference from the dry vs recorded sample is then your IR. While exhaust systems have no digital input, if you have good enough audio gear that can output the signal dry as possible through the exhaust setup, it should achieve the same result I guess. Not that trivial for everyone to do, but if you do this enough times for different kind of exhausts, you'll also have great dataset to start researching and developing a software that can model exhausts accurately.

Re: Engine Simulator: produce realistic sounds from various engine parameters

#23

Post by acutesoftware »

The sounds generated by this are very impressive - it is an actual simulation of the entire combustion process.

Best parts are the engine sound under load, slight delay when opening throttle and changing down a gear to force engine braking.

Re: Engine Simulator: produce realistic sounds from various engine parameters

#24

Post by ynniv »

userbinator wrote: post #21
tonmoy wrote: post #20

Earlier quoted context omitted.

Not sure how one would be able to obtain impulse response of the exhaust system

You can model it as a series of tubes of different diameters. Look up "digital waveguide" for some more details. This technique is mostly used in speech synthesis, where it can make pretty realistic human-speech-like sounds by modelling the vocal tract, but there's no reason it can't be applied to a car exhaust system.

The better car simulators already do this: “Physically informed car engine sound synthesis for virtual and augmented environments” https://air.iuav.it/bitstream/11578/264484/1/SIVE15_submissi...

Re: Engine Simulator: produce realistic sounds from various engine parameters

#25

Post by atoav »

mhh__ wrote: post #17
xbar wrote: post #16

Earlier quoted context omitted.

A second simulator for exhaust systems would be appealing. Perhaps he will figure it out himself, or re-open source the existing simulation once he figures out how to get the credit/compensation he deserves.

I think the issue would be that whereas this I think can get away with just a really fast rigid body simulation, the exhausts and so on would need to simulate acoustics where you have feature sizes in the same ballpark as the wavelength of the sound i.e. your ear will almost definitely be a harsh critic.

I mean there are models in acoustic physical modelling for e.g. throat simulation that break the throat up into a series of cylinders and frustrums that work quite ok. Not sure about real time performance tho.

Re: Engine Simulator: produce realistic sounds from various engine parameters

#26

Post by Inviz »

chillel wrote: post #12
tonmoy wrote: post #7

Earlier quoted context omitted.

If I recall correctly he modeled the acoustics of the exhaust using equalizers and filters, so not really simulated

I think you mean acoustics, not autistics =)

Funnily enough on YouTube in certain areas "acoustic" became a synonym for "autistic"

Re: Engine Simulator: produce realistic sounds from various engine parameters

#30

Post by userbinator »

atoav wrote: post #25
mhh__ wrote: post #17

Earlier quoted context omitted.

I think the issue would be that whereas this I think can get away with just a really fast rigid body simulation, the exhausts and so on would need to simulate acoustics where you have feature sizes in the same ballpark as the wavelength of the sound i.e. your ear will almost definitely be a harsh critic.

I mean there are models in acoustic physical modelling for e.g. throat simulation that break the throat up into a series of cylinders and frustrums that work quite ok. Not sure about real time performance tho.

Works well enough for decent speech synthesis, in realtime.
Post reply on HN