When most people hear the word SPL (Sound pressure level) they might think about rockets, or maybe explosions - at least for the uninitiated. Most audio enthusiast are familiar with it. An even smaller group of people may understand it on a deeper level, bassheads. Not your raving bassnectar bassheads, but the bassheads the eat, sleep and consume SPL and knowledge of the subject. Usually with one goal in mind, which is to get louder than the next guy.
(8 18" Subwoofers demonstrating the mechanics of turning electrical energy into acoustical energy)
It is always interesting to me to see the effect of ripping metal, shattering glass and bowing the roof and floor of the cabin of a vehicle. It's also interesting to me that most people have the thought of metals being stronger than bodies (blunt impact and overall toughness is stronger of course) While metals bend and glass shatters the human body remains resilient to the pressure of the waves of literal power hits it. Being mostly made of water, we are able to experience SPL unlike many other things on this planet.
The closest I can describe it is being deep underwater, sometimes an absurd amount of pressure. Cycling dozens of times a second. The loudest I've heard yet is just around a consistent 166dB which consisted of 40 15"(381mm) square subwoofers on about 50,000 watts inside of a utility/delivery truck.
Once you start passing around 162dB you start to notice some crazy stuff happening to your body. Your equilibrium will be off by a lot. The best way I can describe it is being drunk while being sober. Depending on the frequency being played you will experience different things, around 40hz your lungs resonate. The SPL is so powerful that it can cause you to breath at the the frequency playing, a pretty wild feeling if you're able to maintain your composure. Some frequencies will cease your breathing entirely and squeeze boogers out of your head. While other frequencies can hurt your insides pretty good around 57hz you can get some rather painful sensations in your.. uh, posterior.
As with most technology, car audio has improved with stronger parts; but the overall scheme has remained the same.
In the most extreme SPL vehicles they are louder than 182+dB, most definitely enough to kill someone who is inside the vehicle. Once on that level the vehicle's sound system is operated outside of the vehicle. The vehicle gets bolted together/sealed in preparation to measuring the SPL.
Here is a watermelon in such a extreme vehicle
As you can see, the effect is similar to that of explosive decompression making it's own condensation cloud from the change in pressure.
While amplifiers remain mostly the same over the years, the subwoofer market is an extremely competitive one. Many technological jumps in the recent years have helped create some mind boggling low hertz monsters. As the subwoofers get more efficient at lower and lower frequencies it becomes safer to listen to - shaking at 28hz feels A LOT better than 75hz, to say the least.
As time goes on I can only wonder where SPL goes in the future, when I first got into audio a 140db was loud, then 10 years later, 150db, and then 160db, and now most "loud"(purely subjective at this point) vehicles are reaching 170db without extreme modifications to the vehicles. I look forward to the day a subwoofer will create a shockwave, thus surpassing the decibel threshold of the atmosphere. A basshead can dream.
Deepfog out
