The real secret behind F1’s sound

It’s nice to know that the FIA are bringing in “experts” to review the new sound test in which Mercedes will use—what has been described as a megaphone—a new exhaust apparatus in order to amplify the decibel level of the cars in this weeks test in Spain.

Increasing the decibel level is one thing but the sound itself—or what pundits of the new regulations are now calling “noise”—is the key with much of the concern.

The head’s natural speaker

Decibel level is one thing and perhaps the most tangible element that is missing due to the lack of a comparative visceral experience that uses bone conductance to color the experience. You’re not only “hearing” the sound of the car but your skull feels the vibrations as well and all of it adds to the auditory experience.

Sound pressure is a unique element in the equation but sound is also very subjective. Some of us—and I’m not saying that Paul or I lost any of our hearing from those early rock and roll days—have gaps in their hearing. If you consider the audible range between 20hz to 20khz, then you are closer to understanding the range of the human ear.

Who was Fletcher and Munson?

The ear is sensitive across all those frequencies but we don’t hear all of those frequencies at the same level. For example—if you had all of the frequencies playing at one time and the Volume was set at 10, you would not hear all frequencies at 10. Some would be at 10 while others would be at 7 or 5. You may have heard people say that we don’t have flat response hearing. That’s what this means.

This is why—if you are one of those dudes—you had an 800-watt amp in your car with a cross over and it pumped out the bass in a big way. The reason is we don’t hear low frequency—think bass—at the same level so we put big amps on those low frequencies to increase the volume and artificially “make” our hearing flat in response.

This has a lot to do with something called the Fletcher-Munson curve (yes, they are two guys who invented the equal-loudness curve in the 1930’s). It basically says—and this is putting it very generically—that our ears are very sensitive around 1,800 cycles to about 5khz. This is scientifically explained by the size of our ear canal and other internal oddities like ossicles.

That’s all nice but it’s really much easier than that. You see I believe we were made that way because for one simple reason—the human voice is in that range. We were designed to hear each other although we all do a really good job of not doing that very thing. We have learned to tune that out pretty well haven’t we?

Wait…61 feet?

All things vibrate. Everything oscillates. A 16hz frequency—meaning it oscillates 16 times per second—is 61 feet (18.75 meters) long and if you have a speaker sitting on a long wooden floor, the floor will resonate using 61 feet of the wood. The key to the “megaphone” will be having the appropriate length of material so the frequencies emitted from the exhaust couple with the material and resonate at the right wavelength to make the best use of it and amplify the sound.

The frequencies are much higher from the exhaust so we don’t need 61 feet of material but suffice to say, we will lose much of the low frequency stuff regardless. Now we’re getting to the crux of the matter.

Dude!  We need more power!

If we can amplify the sound of the exhaust that would be great wouldn’t it? Well…maybe. You see when you double your power, you increase the gain by 3dB. Now keep this in mind when you are buying your stereo—adding more power is not always the best investment. If you go from 300 watts to 600 watts, you’ve increased your gain by 3dB and you can barely perceive that. You have more headroom but in the end, it is much better to get a more efficient speaker than continually doubling your power.

So the Formula 1 megaphone needs to be efficient at how it conducts with the frequency as a speaker needs to be efficient with how it uses the energy you send it. Can in we increase the overall gain output of the sound of the exhaust? Sure but is that enough? In my opinion, it is only half the battle.

What’s the frequency Kenneth?

You see the frequency is a real issue here. When a motor revs at 18,000 rpm it emits certain frequency characteristics that we have become used to. These new engines do not come anywhere close to producing the same frequencies at the same levels and the overall gain is down due to one exhaust outlet—among other things. It is the color or nuances of the sound that F1 fans are missing as well as the visceral gain structure of the sound itself.

In short, you have a gain and frequency issue. They may be able to solve on but they will never solve the other, naturally, without the engines revving at a much higher rate and when you add more cylinders it gets even better. Couple this with phasing issues and more and you have a right mess.

Speakers breathe?

Regarding phase (remember the notion of 45 degree angles), here’s a top tip. Always make sure your speaker cables have the “plus” connected to the “plus” and the “minus” connected to the “minus”. If you don’t, the easiest way to think of this is that when one speaker is moving outward or exhaling if you will, the other one is inhaling or moving backward. That’s out of phase and that’s not good. Phasing is how your Bose QT headsets work too but I won’t get into that now.

Now this becomes important for one reason, fixing the overall gain of the exhaust is one thing but broadcast has a completely new curve to throw this whole issue. Compression ratios of the audio in the broadcast and how microphones around the circuit are placed and if they are in or out of phase etc. It get’s very complicated if we’re trying to get the sound on TV better too.

Here’s the real black art that could fool us all

Here’s the black art of what they could do for us couch pilots at home though—Digital Signal Processing (DSP). You see you could easily run the circuit microphones through a DSP and modify the frequency and gain with relative ease. You could pump the low frequency up and make the response as flat as possible. You could even find high frequency harmonics and amplify to crap out of those and make us believe we’re hearing a little bit of a wail like we did in the old days. I even know the product that can do that well but F1 will have to call me for that solution—but I’m sure their “experts” will do just fine. This is like the Adrian Newey area of audio and much can be done at this level but it doesn’t impact fans at the track.

Broadcasters know how to bounce video off the Clark Arc 22,300 miles away really well but they wouldn’t know audio if it bit them in the arse. They believe that audio is just something that comes free with video. Tragically audio is the most complicated part of the broadcast because of what we mentioned above—it’s subjective. Paul may be sitting at home with a huge hole in his hearing between 12khz and 16khz and he’s thinking this sounds like dog poop when it actually sounds fine.

So there you have it. The challenge before F1 is trying to increase gain and also to somehow hope that fans will still like the quality of the sound via its frequency characteristics. Louder crap is just louder crap. If Force India’s Bob Fernley is right, then we may grow accustomed to the “crap” and find the increased gain is fine. Time will tell but I wish the “experts” well. While they’re there, maybe they could take a look at the circuit sound system and test the free-air cone resonance for each speaker at the track.

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