Thoughts on sound dynamics and sound balancing

As sound is a big factor of immersion in any simulation here are some thoughts on sound dynamics and sound balancing in AMS.

First, on sound dynamics:

We all know the doppler effect and what it does to the pitch of sound when cars approach, pass and depart again. This is neatly simulated in most sims, AMS included. But what does it do to volume? Here, AMS and many other sims leave big room for improvement.

First, please have a look at the figures attached: These show how sonic waves spread when the sound emitting object (in our case the opponent car) is stationary and when it's on the move, respectively. Now imagine our position is the blue dot = the player car. When both player and opponent car are stationary, and given the fact that the player car is silent, the opponent car is audible at approximately half its volume according to the upper picture (player car is within the sonic waves). If, in contrast, both cars are moving at the same speed and into the same direction, figure 2 shows what should happen to the sound: At the same distance the opponent car's volume now is notably reduced, maybe it's even barely hearable. (Note: in both cases the emitted volume is the same, neglecting a higher volume at higher speeds.)

schall.jpg


And this is where AMS seems to be wrong! The opponent cars' volume is calculated like shown in figure 1 always and at any (relative) speed which leads to cars driving behind you being a) way to loud and b) audible from too far away. In return, cars drawing away from you should be audible way longer and at higher volumes. The effect should be stronger at higher speeds and weaker when going slower. Maybe you have been driving on a racetrack yourself IRL, but most probably you have been overtaken by a screaming car on the road at one point in your life. What you may have experienced, especially when you or other passengers were not prepared, is a cringe when the overtaking car suddenly is level with you, and that it's audible significantly longer when being in front of you. The exhaust now blowing directly in your direction may amplify this.

It would be great for immersion and realism if AMS's sound engine could model that more exactly one day! :)

Now, on balancing:
I recently had a mixed practice session in AMS with several cars. Myself in the Camaro (the most silent of all) against the Minis, Opalas, StockCar V8s, Super V8s, Boxers and MetalMoros. Apart from turning out the upper it brought up problems with volume balancing between the different car types. Of course this may be subjective a bit, but at least I'm having other expectations. IMHO the MetalMoro is way too loud, followed in a lesser extent by the Opala. This is quite disturbing when either of them approaches from behind. On the other hand, especially the Boxer should be way louder and menacing and even the Mini could use a bit more volume. Both the V8s are fine.

I'd love to hear your opinions – both users and developers – on these matters. :)

Cheers, Oliver
 
I thought AMS does actually calculate that? Else we also wouldn't have the dopler effect?

I think it's just that the volume of your own car is insanely loud so that this effect isn't as noticeable as in your street car?
 
I'm not sure about that.

As a real life example, maybe a thought on Nordschleife tourist sessions could help: The sound setting of these is quite comparable to a race with mixed classes. I have been driving there in quieter and louder cars as well and the effect is always the same. To remember a recent situation in one of the flatout parts of the track like Kesselchen: There was a GT3 approaching me, maybe 100 metres away, that was just not audible. Its noise set in – at the earliest – 20 metres before overtaking me and after that was ear-piercing even being more than 100 metres away. Does this explain it a bit better? Sadly, most YouTube-Videos don't do that justice, otherwise I'd like to point you there.

A developer's statement on that would be greatly appreciated, especially on how the doppler effect is generated. :)
 
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