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Is Sound an Illusion?

© 2009, Les Acres, Rod Elliott

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I have, for many years, studied sound.  Subjective, as well as from an engineering point of view.  It is not easy to quantify what one perceives.  The actual hearing process is extremely complex.  No two people hear the same.  Sounds may or may not be shown as identical but the listener is having the sound analysed by a brain, which of course is totally different from every other brain, it is also the sum of all experiences.  Not only do I believe that sound is an illusion, I believe that it is the reason for more artistic sounds - a sound must be the most difficult thing in life to describe to another.  Instruments for example, also have a "voice".  Natural baritones are preferred as orators and announcers not because they talk low but because their voices are rich in pleasant harmonics!

I have long experienced that if a sound is offensive in a mix, the listener will say, "It's too loud!" Only a trained listener or a musician has any chance of working out what the listener finds offensive.  Even if the sound which is offensive is identified and turned down, the listener will still find it offensive and everything is still "too loud!"

Catch that same listener listening to a piece of their favourite music on their hi-fi, and you would not believe how loud they are playing it! Offensive is offensive.  No-like is no-like and that's the end of it.

Often if a sound in an audio mix is not clearly audible, the answer is usually to turn it up - no one ever stops to think that it might be because something else is too loud! At some gigs a game of see-saw is played on the monitoring until all you get is instability or screaming feedback! Correct equalisation is sometimes the only way to separate things.  Whoever sets the monitors is not a mind reader, so good communication is essential.  There's no need for the non-technical to learn technical things - just say it like it is!

If it relates to music, the offending person involved will often resort to artistic tradition and say, "It's my sound" if s/he sticks to his/her guns, whilst, laudable from an artistic aspect, it will soon be realised that people will not part with their hard earned money to hear it! Musicians also do not like working with someone who is not a team player – there are plenty of prima-donnas around who demonstrate this very clearly.

Minute timing differences in a recording studio seem huge, yet at a concert every musician and the others taking part are all at a different distance from the listener! Sound at sea level and average atmospheric pressure travels at about 345 meters per/sec, which amounts to 345mm a millisecond.  This is about 1.13 feet (13.6 inches)! In a concert situation, the differences are rarely heard or noticed, even when there is a combination of direct sound from the stage and the miked sound from the PA.  In isolation, the human ear/brain combination works on the most minute phase errors and timing errors - so much so, that if you drop a pin onto the floor in a quiet room, most people's eyes will immediately flick to the position where it landed!

That, coupled with the minute phase differences between the musicians, gives the third dimension and the true stereo effect.  The emphasis being true.  These phase and timing differences can also give different sounds height information too!

This is often exaggerated in recording and even live performances.  If it is exaggerated in live performances my brain and ears cannot cope with the fact that my eyes and ears are giving conflicting information.  I might stay, but I don't enjoy it! Stereo can be either correct reproduction or a pleasing effect.  Overuse is tiresome - it might sound good in the bedroom but in real life, it's different! Keyboards are a good example, at a distance even a grand piano looks small - it is therefore mono, misuse of stereo and panning can make it seem 25 metres wide! Is that artistic interpretation, a pleasing effect or rubbish? Take your pick.

MP3, which is fast becoming acceptable for the transfer of musical Information, was originally developed from the Philips' DCC software, which works (simply) on the fact that if a sound is louder than another, the quieter one cannot be heard ... so it simply throws it away! Audio masking is a well studied and documented effect.  It can lead to the monitoring problems to which I have already alluded.  This is how digital compression (which it isn't) is used to transmit files of manageable proportions.  If something is compressed it can be restored by expansion following the same law, but MP3 can't, as the missing information has been away! Audio, of any fidelity creates huge files! Listen to the same recording side by side with a CD, and you'd have to be deaf not to notice the difference! Sound quality has certainly gone down with the 'Digital Revolution' although it appears to have gone up! Chips with everything I suppose! I cannot see the point of developing a technology simply because you can.  A friend said to me once, "Have you ever listened to a DAB radio? It sounds like an old fashioned wireless with a sock stuffed in it! (It's quite perverse actually as he is acknowledged as being a world authority on digital sound!)

Another illusion common at concerts is the fact that the vocals may be hardly audible yet people are singing along with them while others are looking around and wondering if they ought to see a doctor.  This is the easiest trap of all, for the sound engineer or sound mixer to fall into.

If you are familiar with the words of a song or even know them, you think you can hear them! Such is the power of the brain to interpret.  Never underestimate the power of the subconscious! The cure is simple; just throw the engineer out of the concert and wheel in someone who knows what he's doing.  Simply telling the idiot to turn up the vocal is of no use if he's already used up all the PA's headroom showing off! If any limiting or compression is applied and the peaks of the music are too high in the mix the vocal will be compressed or limited down! Ergo, no vocals! If the sound system is inadequate it is inadequate.  If the band on its own is hitting the vocal mic louder than the singers mouth, automatic limiting in the equipment will still limit, it does not know nor care what is too loud, it will limit.  This will add to the problem of having an inadequate sound system.  The vocals need to be clearly heard to those unfamiliar to the material.  It this happens regularly you may as well sack the singer(s) and there is more money to go round at the end of the night!

If a concert is modest in size, which amounts to most of them, then what you perceive is different from what you think!

The perception of the audience is in fact a 'mix' of the performers, the monitors and the PA.  Monitors are necessary for the musicians to hear what they are playing and for the singer(s) to hear what they are singing.  It is necessary for some instruments too, even those that are quite loud anyway (horns for example), because loud to you and me is not to the player because the sound of the instrument is going away from him/her! Very little comes back to the player when playing into the crowd.  Unfortunately the monitoring sounds “muddy” to the audience because the floor and/or side monitors are facing away from them, but they can still hear them close to the stage.  Another compromise to meet!

It has often been a criticism of recordings from the desk being, different from the perception of listeners at the concert.  I have often heard this criticism and I normally say, "It sounds as though the engineer was doing his job!" The PA is carrying the vocal to the audience, hence sounds too loud.  It often seems to lack bass because the PA is trying to compensate for the monitoring.  Also the PA is compensating for the instruments and their amplifiers.  Sound decreases by 6db for every doubling of distance, and it is also frequency conscious, higher frequencies do not travel well.  Some seem to fall off the stage and go no further! The bass can be heard a mile away to the detriment of everything else.  If you know anything about evolution, you will understand why.  It is also due to a fundamental law of physics too.  One only has to see the response from young children to see their reaction when the Hi-Fi is turned on.  They always complain the bass is too loud, look closely and you will see it actually frightens them!

Dinosaurs and large wild animals once walked the earth; early man was an easy meal.  It has been discovered that dinosaurs must have made a very low bass sound which not only carried a long way; it used to scare the pants off any humans that heard it! (Probably in those days pre-human would be correct and they wouldn’t be wearing pants, but it sounds good dontit?) As children grow up it stops being frightening and instead is exciting in the naughty sense and every promoter knows that you sell more beer if the bass is high!

This, of course cannot be argued with (but see the Note just below).  The human ear is also a victim of the Fletcher-Munson curve, where the perception of volume is frequency conscious as well as volume conscious, again due to evolution which is why high fidelity audio equipment has (or had) a 'loudness' control  This is why sound is often declared as "too much middle!" That is the vocal range, essential for communication at which the ear is the most sensitive.  The ear has a certain amount of natural protection against loud noises.  Often referred to as compression built in.  So dial in the 'smiley face' play it loud and the vocal disappears!

Therefore can you trust what you hear? Do you know why? Or do you even care?

Note:   Naturally, we all know that dinosaurs and (pre) humans didn't cohabit the earth, and this should be taken in the sense that was intended - namely 'poetic (or artistic) licence'.  There is no intention to imply that there was a change in the order of history as we know it   .    There were no doubt plenty of things to scare the (non-existent) pants off our early humanoid ancestors, and low frequency sounds in particular would rarely (if ever) signal the arrival of anything good or welcome.



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Copyright Notice. This article, including but not limited to all text and diagrams, is the intellectual property of Les Acres and Rod Elliott, and is Copyright © 2009.  Reproduction or re-publication by any means whatsoever, whether electronic, mechanical or electro- mechanical, is strictly prohibited under International Copyright laws.  The author (Les Acres) and editor (Rod Elliott) grant the reader the right to use this information for personal use only, and further allows that one (1) copy may be made for reference.  Commercial use is prohibited without express written authorisation from Les Acres and Rod Elliott.
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