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The curse of bass, and the future of hi-fi

When you live above neighbours who don't give a shit and who never answer the door, and then play loud bassy music all weekend, it's depressing. It's kind of similar to the curse of those stupid cars with extremely loud woofers in - you get loads of those in East London. When a car goes past my office and literallly fills the room with loud bass, rattling the windows and other loose objects, the thing that I don't get is: how loud is the bass inside the actual car? Is it really mind-meltingly loud? Or is it actually quieter than the bass we experience from 10 metres away through a brick wall? Most likely it is quieter, because bass frequencies take a few metres to develop into coherent waves (because the sound wavelength becomes long enough to be comparable with the size of the resonant object) so the person driving the car probably doesn't get the "full benefit" of their speakers. (The point of those car systems is for showing off too, so in a sense they do get the full benefit.) It's similar for the neighbours downstairs - a lot of their bass leaks out into the surroundings, which presumably is an unintended side-effect.

The answer isn't to make hi-fis which don't make loud bass, because no-one would buy them. But I wonder if there could be a technology which generates bass in a more specifically localised way, rather than the traditional way? There are technologies based on multiple speaker arrays (e.g. this magnetic audio device) or on ultrasonic interference techniques (e.g. this american patent for ultrasonic audio projection) which can transmit sound in a focussed way - the sound doesn't just radiate out from some object. These techniques are a long way away from being used in home hi-fis, but maybe one day they'll become relevant.

I can imagine the home hi-fi makers would like to be able to market something with this kind of projection in. Imagine being able to put your hi-fi "speakers" anywhere you wanted (e.g. somewhere out of the way) and having the sound appear to come from wherever - from the middle of the room, from the telly, or following you as you move around the house. That has some nice potential. Perhaps as a side effect, this kind of sound production would have less leakage (because it uses interference effects to strengthen the signal where it's aimed, and similarly to suppress the signal where it's unwanted). It could in theory waste less power in the same way modern lightbulbs do - by dissipating less energy in unwanted forms (or unwanted directions, in the case of sound). Let's look forward to that.

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