It seems to me, because it can’t be seen, sound is always considered to have some sort of magical and mystical behaviours.
Well, sorry, but, hell no.
Beside its tendencies to get reflected by every single thing slicker than a sponge, and its bad habit of being rather slow, sound’s behaviour is pretty much predictable. Deal with it.
No helicoidal spiral copper wire, no oxygen free cable and no reflection- killing paint will do any good to your sound, despite what numerous hi-fi enthusiasts, ads in professional magazines or sound “astrologist” will have you to believe.
I know sound can feel a bit like playing a pool game in a room full of mirrors whilst high on LSD. It is, in fact, a tad more confusing than that. Nevertheless, this utterly confusing behavior is repeatable, again and again.
Should you do the same thing, like aim your sound source at a wall this way or that way, sound will consistently come back at exactly the same angle with exactly the same characteristics, despite planets and galaxies moving around, and despite what some will say. The trick is to understand what is happening; and I agree, this may take some serious time, and a fair bit of knowledge and understanding.
Luckily, you can leave that to ‘professionals’.
A good way to select a serious sound professional is to make sure he or she is as boring as possible. You are looking for an engineer after all, not for a Chippendale. So geek style, sneakers, black t-shirt, pony tail or even socks worn with sandals; these will probably be the types of people you can trust about sound. You want to aim for Asperger’s like features. Even a tiny bit of autism could be in order… that would be a good sign. You would probably be getting bored and confused rather quickly when chatting with ‘the chosen one’.
On the other hand, I’d be a lot more cautious if some guy in a nice suit starts being all charming, and making you dream and speaking so well about how ‘marvelous’ and ‘beautiful’ sound is (me being the exception obviously!). Tha would be the door to beliefs & mysterious territories; things that do not have anything to do with sound and its basic, scientifically proven, boring, properties.
In case you are interested, let me roughly summarize these basics:
– Sound is slow. About 1200 km/h (while light is seriously fast, say a tad more than one billion of km/h).
– Sound can be seen as a bunch of waves. The longer the waves the lower the sound.
– A low frequency sound wave is in the meter range; say 3 meters for a good groovy Ibiza bass line.
– A high frequency sound wave is in the millimeter range; say, 3 millimeters for a motor bike about to implode at full throttle in 1st gear.
– Low sounds tend to go around and across things. High sounds can be stopped, even by something thin.
– Low sounds can be stopped too… by fairly big, dense and thick things, like very large bunkers or reasonably sized mountains.
– Sound is reflected by hard surfaces and absorbed by soft surfaces…
– Sound will lose its energy when moving through air, mostly at higher frequencies where the sound waves are very small.
– When sound happens into a space, for example, a room, or a piece of material (like wood) it tends to make these things resonate. The resonances happen in dimensions of multiples of the wave length. So an Ibiza bass line will tend to be utterly annoying in a cube of 3 x 3 meters (even more utterly annoying than when played on a nice beach on a Spanish island). Whilst the sound of a motorbike about to die would tend to resonate a lot in a wooden panel or in a classical guitar. Luckily sound of motorbikes and classical guitars don’t get mixed that often though. But these are examples of resonances.
– You can mix sound waves together, just like what happens in a harbour with lots of passing boats. You get a bunch a sloppy uncoordinated stuff instead of a nice set of smooth tropical evening beach ambiance. That is ‘interference’.
– Sound decreases with distance. Double the distance and you’ll loose four times the energy*
*This first and foremost rule that sound follows is a rule that just about anything on Earth using energy follows: Energy is diluted 4 times every time the distance traveled is doubled. This works for light, heat, magnetism, gravitational fields of planets, whatever. This is due to the 3 dimensional nature of our world where the energy radiates in a sphere; double the distance, the sphere surface will be 4 times the size it was before. This is called ‘The Inverse Square Law’.
See? Boring, repeatable and predictable geeky things.
OK, sound is slow, but how slow is it really?
Well this depends, and that is not an answer that helps in achieving a spotless social network perception for it in the general public. First and foremost, sound moves at the speed… of light, (while travelling in wires that is). So as long as you keep your sound canned in cables, amps or electronic apparatus, everything that is happening is happening in near “real time”, very close to almost instantaneously. In there, sound moves at 300 millions of meters per second, or 300’000’000 meters per second or 1000 millions of Kilometers per hour. And since wires are one dimension only instead of 3, sound and other stuff do not there suffer form the energy loss of the inverse square law, btw.
All cool and easy so far.
Things really become fun and vastly perplexing when you change medium for example when your sound signal is emanating out of loudspeakers to reach the free open space filled with air. Then you really are in trouble!
So far, sound was moving instantaneously and in straight lines, neatly following the copper conductive path traced by cables and machines, but now, oh my, sound slows down to almost a halt. And, as if not happy enough to be utterly annoying with it’s almost stopping attitude, it also spreads out, like super slow multiple mad flies, in an almost 360° direction. Then from that very moment, sound travels at the speed… of sound (I bet you guessed that bit), and moves just about anywhere it feels like, in about every direction. This means that, while it was happily moving at about 1000 million Km/h before, it now lags at a mere sluggish 1200 Km/h, or 340 meters per second, whilst light, emanating at exactly the same time from the very same high end fancy home cinema installation, continues its path in free air…. at the speed of light. That’s it.
Now go and try to explain that to your neocortex.
Fun fact about sound 1 – Avalanche warning system
In central Europe in the early 21st century, a university implemented a trigger system in the mountains to detect Avalanches and activate appropriate warnings.
All was cool but they kept on getting false positive. Quiet rumbling sounds seemingly coming out of nowhere were regularly registered by the sensors. It took a fait bit of work and insight to come up with an appropriate explanation. But they did. It was the Concorde. Concorde was a fabulous supersonic passenger jet plane built by a French/English consortium, a miracle in its own right, capable of crossing the Atlantic rather quickly with 100 or so first class passengers and arriving in New-York before it left London or Paris, with time zones offset taken into account, of course. Concorde was taking about 3 hours to cross the Atlantic while today it requires a modern low carbon footprint Boeing 777-200ER or Airbus A330-200F about 7 hours at best for the same ride. Concorde’s trick was to fly supersonic, at about 2000 km/h. As you may know, supersonic flight implies that an aircraft penetrates The Sound Barrier, at about 1200km/h. When an aeroplane penetrates the Sound Barrier, it not really generates a large bang – known as a Sonic Boom – it in fact generates more of a continuous noise that appears as a bang when you are stationary on the ground and the plane flies by, this is somewhat referred to as the boom carpet. So, for the sake of saving a fair bit of glass and windows every day on the inhabited ground on its path, Concorde’s supersonic flight were restricted to happen over oceans only.
Nevertheless, you may have guessed that by now, the sound of Concorde going supersonic over the Atlantic was picked up in The Alps by the Avalanche sensors. Now because of the sheer distance involved, about 1000 km, the sound reaching the Alps was faint, very quiet and in the very, very low frequency range, but still, it triggered the sensors
The list of regular sound behaviours above pretty much explains what was happening to Concorde’s noise on its way. If it started at say 150dB and was loosing 6dB (4 times the energy) at every doubling of the distance, you were ending up with around 40dB of residual Concorde sound in the mountains, which is substantial. While these 40dB had lost all their high frequency content on the way travelling through air (and thus were not really noticeable by the human ear), the sensors were seeing about 40dB of very low rumbling stuff. With the very basic take on life perfectly normal electronic sensors may have, it was considered by them that they were detecting a perfectly normal avalanche. Therefore, even though these were neatly matching trans-Atlantic daily supersonic flight schedule, sensors would regularly trigger daily false-positive warnings and go one with whatever sensors do with their life when left alone in the wild white cold of The Alps’ summits.
Concorde was retired in 2003 due to high operating costs and pesky government issues, but won the BBC’s 2006 British Design Quest, beating the Jaguar E-Type and the miniskirt…
This post is also available in: French
