Articles and whitepapers

Sound reproduction in the 21st Century (1/3/2006)

By Chris Metalle, The MAX Distribution

Loudspeaker design is moving on and into new fields. It is no longer simply the blend of aesthetics for the eye and sound reproduction that is indistinguishable from reality. New aspects of the listening experience are coming to the fore and today's installers and their customers have more than baffling baffles to worry about!

Instead merely of asking the question 'What do you want to hear?', professionals need more and more to broaden the issue to 'What experience do you want to create?' Sound is only a part of the effect - visual stimuli obviously feature, but what about the rest of the senses? Surely you want to feel as if you are there - be it in the thick of 'Saving Private Ryan' or conducting the Royal Philharmonic with your air-baton.

Theme parks have long understood the power of creating effects beyond the visual and aural - new cinemas designed to incorporate even more effects are known in the trade as 4D! And because the home-owner can now have these too, he/she wants them.

From noise to experience

Creating a sound is relatively simple. We all remember our school biology lessons where we learned that our ears pick up air vibrations caused when a sound is made, and that, therefore, all one needs to do to make a sound is to move the air in some way. The variation in the sounds we hear comes from the different ways air is moved and waves created.

Sound waves reaching the ear

Speakers are basically movers of air - a diaphragm is electronically pushed and pulled to re-create the sounds contained on the recording medium being played. The better a speaker can vibrate at exactly the correct frequency, the more true-to-life will be the resultant sound output. The air movement produced by the speakers is interpreted by the human brain as sound when the eardrum is moved and the signal changed back into an electrical signal.

Speaker characteristics

The big problem speakers have is the need to use different designs and materials to produce the sounds at low, mid and high frequencies. Our ears have no such problem - they function from broadly 20Hz to 20kHz without the need to switch from one system to another.

For speakers to reproduce sound accurately, they need to split the sound into two or three frequency bands and use mid-range woofers and/or sub-woofers to deal with the lower frequencies. Of course, speakers can have the advantage over human ears in that they can reproduce sounds outside the band we can hear, but so what?! Until dogs acquire significant spending power, it is unlikely that such features will translate into benefits for speaker manufacturers.

There is a great deal of technical stuff related to how sound pressure and electrical voltage are linked, and speaker manufacturers are constantly attempting to push the limits in terms of how powerful their products are at varying distances from the listener and at different power inputs. Cones, horns and ribbons have all been used to generate sound in speakers. There are advocates of each form and of the numerous materials used in their construction.

Ribbon tweeters, such as those used by BG Corp in its Radia Series speakers, can make a huge difference to the quality of the sound reproduced, as they focus the sound rather better than cone speakers, thus avoiding the interference so often experienced when sound is bouncing off of all surfaces in the room. These speakers make a 5.1 surround sound system really special - clarity of sound and pinpoint imaging create an awesome sound field in even acoustically 'live' environments, such as those with hard surfaces.

The BG Corp Radia Series speakers with ribbon tweeters

Get a feel for it

Until fairly recently however, speaker manufacturers concentrated exclusively on designing better ways to move the air around, and this ignores many other aspects of the total audio experience. For instance, when the timpanist in the orchestra hits his/her drum, we feel the vibrations as well as hear them. This is not merely the feel of moving air - it includes vibrations which are fundamental to our total appreciation of the power and depth of the sound.

New speakers on the market recognise this need for more than sound. Tactile Transducers from Clark Synthesis, for example, add this element into an audio set-up without displacing existing speakers. These are not simply additional sub woofers or bass drivers, but full-range transducers that add a tactile element to the experience.

For the listener, the difference is tangible - akin to the change from no sub-woofer to having one. Instead of turning the volume knob to 'Lethal' to achieve the full effect of the crashing drums or roaring engine - not to mention the approach of T-Rex - the user can experience it without annoying others in the house. You can even enjoy the full range effect underwater in your pool!

The Clark Synthesis Aquasonic underwater speaker

Walls have ears - and now mouths

Other innovations which greatly appeal to interior designers and the spouse who hates large obstructive and ugly boxes in every corner of the room, are speakers which are completely invisible. Forget on-wall and even in-wall, now there are speakers that turn the wall itself into the speaker. SolidDrive sets from the US, installed in Disney's Epcot Center, are installed beneath tables, on windows and within walls, and turn many flat surfaces into fully-functioning speakers. Imagine the effect - all the sound and none of the wooden boxes!

So innovative are these SolidDrives, that retail shop windows, boardrooms and public galleries are queuing up to have sound produced with no visible speakers.

The Induction Dynamics SolidDrive set

Summary

Never has it been more appropriate to talk of thinking 'outside the box' when it comes to sound reproduction. Speaker design has moved a long way in recent years, albeit the constraints of what the human ear can perceive remain. The options available to the home owner and designer are far more varied than they were, and innovation is now the name of the game - not just in the way speakers look but in how they can be integrated unobtrusively into any environment.

Chris Metalle is a Director of The MAX Distribution Company, distributor of high-quality speakers for home cinema, gardens and under-the-seat, as well as a broad range of installation and testing tools.

The Max Distribution is no longer in buisness.