In recent months I’ve found myself pulling up in traffic queues to find the car suddenly filled with low-frequency thumping of the kind I’d normally associate with a failed big-end bearing. Every time it’s been the car ahead of me, which has its stereo blasting away for the benefit of everybody in a wide radius. I get them at home too – I’m often sitting at my desk quietly writing and the room fills with the low-frequency thump that heralds a car belting down the road with sound system blazing at 11. I keep thinking it’s the human equivalent of gorilla chest-thumping. A declaration, in short, of presence and power.
The physics of why this happens are clear. Lower-frequencies are audible at far greater distances than high, and – more crucially – become audible at greater distances. A bass note, let’s say of 27.5 hz, which is the lowest note on most piano keyboards (A0), has a wavelength of about 12.5 metres at sea-level and comfortable room temperature. This means it doesn’t reach full amplitude until 6.25 metres away from the speaker. That’s where the volume maxes out. Then the cycle repeats with slightly diminished amplitude until, finally, the rarefaction and compression it causes is lost amidst the usual movement of air molecules (Brownian motion, since you ask). Picture the ripples from a stone thrown into a calm pond. It’s an identical principle. It also means that bass volume is actually at a minimum right next to the speaker, because the wave is at minimum amplitude. High frequency sounds follow the exact same principle, but because the wavelength is shorter they reach maximum amplitude at much shorter distances.
You see what I’m getting at – these people wham their car stereos to massive volume so they can get the bass to the same level as they perceive the mid-range and high-frequency volumes inside the car, with the result that the bass is stunningly loud where it reaches maximum amplitude outside the car. And when you hear the thump from over 200 metres away, it’s clear their car sound system is whacked up to at least 11.
I also have a suspicion that what they are listening to has no top end anyway. The style of music chosen by these ‘car blasters’ always seems to be the same. On occasions when they’ve driven past, windows down and sound system blazing – close enough that I should hear top end – there has been little sign of anything other than TR-808-style drum-and-burp at around 20-40 hz, the very bottom of the audio sound range, overlaid by someone angrily shouting about revenge against society.
What worries me are the safety issues. If a vehicle is filled with sound, it’ll mask noises from outside, dominate the driver’s rhythm of movement, alter their heart-rate to match the beats-per-minute of the music, and change their mood. All that, to me, spells interference with situational awareness and the movement rhythms needed to properly drive, by which I mean the timing to properly take corners, handle the car and so forth. These are dictated by the nature of the road, not drum-and-burp rapping at 95 beats a minute. And that’s quite apart from the aggression issue, which getting into a car is well known for provoking anyway – as Walt Disney lampooned, decades ago.
I don’t mind loud music as a rule. There are only three kinds of music I actively avoid: country, western and rap. Other than that I listen to all sorts, including power metal which best works with the amps wound up to 11. But not when I am driving.
Copyright © Matthew Wright 2022