The Problem

Conventional speakers don’t satisfy
the needs of today’s consumers. Why?

Because traditional speakers’ optimum performance can only be perceived by a listener sitting in a specific place relative to the speaker(s). All the while, today’s consumers lead a high-paced, individualised and multi-tasking lifestyle that demands flexibility, freedom of movement and products that can be easily situated to accommodate interior design choices.

Traditional speakers don’t fit the bill. So what would make the ideal speaker?

The ideal speaker should have:

Only this way will you have a speaker that delivers the same sound to your ears – wherever you are in the room.

Which means, the usual technique of placing the drivers for the midrange and high frequencies in the front of the speaker does not achieve the ideal speaker.A speaker with Flat In-Room Response in front and all around of the speaker simultaneously

Conventional speakers with the drivers for midrange and high frequencies placed in the front, can either be Flat On Axis, or have Flat Sound Power Response, but not both at the same time, because of the high frequencies’ directivity, so manufacturers are forced to compromise.

This failure results in an uneven dispersion of the sound in space.

On Axis and Sound Power

The failure of speaker designers / manufacturers to create the perfect loudspeaker has established two different design trends:


Floyd E. Toole: Sound Reproduction – Loudspeakers and Rooms, Focal Press ©2008, ISBN 978-0240-52009-4

A. Flat On-Axis speakers sound good only in specific listening positions (Figure above), and best at the sweet spot (401) which, according to the ITU-R, is the apex of an equilateral triangle with the other two apexes be the two speakers L (402) and R (403). However, when the listener moves away from the sweet spot the soundstage changes, shifting its centre along with the listener.

B. In the Flat Sound Power design trend (Figure above (a)), a flat frequency response of the average of the measurements around the listening area (201) is intended. The sound in this instance is pleasant, even at positions further from the speakers, where the reflected sound is stronger than the direct, especially in large listening rooms (thanks to its rich reflections that stimulate more evenly in all directions). This experience is closer to live music.

In recent years, the Flat Sound Power design trend has been replaced by the Flat On-Axis. Typical examples of Flat Sound Power technology were the once very popular studio monitor speakers Yamaha NS-10M (Figure above (a)), the domestic Bose 901 V, Bose 501, Bose 301 etc.

One of the most famous and successful researchers and speaker manufacturers is Bose, a company that has presented innovative speaker technology, most notably the direct - reflected sound speakers ( 901, 501, 301 etc ) and smooth Sound Power. The company’s researchers, despite their long-term efforts, did not manage to create speakers with both Flat On-Axis and Flat Sound Power Response, because while they were holding the Power level constant at all frequencies, the On-Axis level was continuously rising along with the increasing frequency. ( Patents US 3.582.553, 1 Jun. 1971, «Loudspeaker System» and US 3.727.004, 10 Apr. 1973, «Loudspeaker System»).

This is the problem that WiSound™ Technology solves.

In existing loudspeakers, directivity is not constant, but shifts significantly (up to 10dB) depending on the frequency, with the sole exception of the constant directivity horn speakers, which have constant but very high directivity (eg Electro Voice), ie the Sound Power response level is much lower than the On-Axis. In practice this means that conventional speakers show smooth gradual drawdown of sound as we move away from the sweet spot. WiSound™ Technology solves this problem by achieving ideal zero directivity.

Feeling of space

– the feeling of being in a large space with live music. It is measured by the level difference of the Reflected Sound to the Direct Sound at the listening position.

One other problem that WiSound™ Technology solves, is the unnatural feeling of space created by the reflected sound speakers. The speaker manufacturers of this type (most prominently Bose), base their technology on the observation that in a typical indoors concert hall, listeners hear 87% of the sound of music from reflections. So, they created speakers, in which the direct On axisThe measurement of a speaker’s Direct Sound, just in front of the speaker’s radiation axis, in an anechoic chamber. sound radiation is much lower than the Sound Power that determines the intensity of the reflected sound.

However, although the effect is impressive when playing a large orchestra, the soundstage does not have the clarity needed, as it enlarges excessively the feeling of space and the organs lose focus in stereo image. So the singer's voice, for example, instead of being located somewhere on scene, it seems to be coming from a huge mouth, that big as the wall behind the speakers!

WiSound™ Technology solves this problem, by balancing the Sound Power with the On axis.
The majority of speaker designers today prefers manufacturing speakers with On Axis flat response, placing the high frequencies drivers on front.

This design trend, Flat On Axis, (Figure above (b)) is  seeking, as mentioned above, flat frequency response on axis (205) (at an angle of 60 ° in ITU-R) and in the begging it found supporters amongst professionals (sound engineers, musicians, etc., as the sound is clear, with limited reflections). Now most speakers, even for home use, are manufactured using this technology.

Previous patents to approach the ideal

Existing technology’s closest approach to the desired (ie simultaneously Flat On Axis and Flat Power Response), are

But none of these speakers has balanced directivity simultaneously horizontally and vertically; but just horizontally, so that the sense of space and specially the sense of height is limited to the height of the tweeter.

Multichannel approach

The sweet spot (401) according to the ITU-R, is the apex of an equilateral triangle with the other two apexes be the two speakers L (402) and R (403).

An attempt to solve this problem was made, by adding a center speaker (404 ). And a more comprehensive effort to solve the problem of the non-uniform frequency response in space is of course the multichannel audio technology (402 to 406) developed in the recent years, combined with the digital audio processing and equalization. Characteristic are the specifications of THX, Dolby, DTS.

The existing multichannel audio technology uses separate 5.1 speakers for the horizontal plane, and more in addition for the vertical plane (e.g. the 6.1 Implementations of Yamaha, or even with more speakers, 7.1, 9.1, 11.1, etc.), which are usually hanged high in the front or back to add the feeling of height to the soundstage.

But also in the multichannel sound, the directivity problems remain: The Sound Power and On Axis response curves of the existing technology speakers are not parallel and uniform even for the constant directivity speakers, which have high directivity above 5db, or even10db.

Even after the digital space equalization it is not possible to achieve the ideal. At best, there are more than one sweet spots (401), (listening positions, where the sound is correctly heard), but the sounds is never uniform at all listening positions.

These directivity problems remain also when some of the multi-channel audio channels (the surround and sometimes the central) are being replaced by virtual channels, through strong digital sound processing. These devices have trade names like SoundBar or Sound Projector and are manufactured by many consumer electronics companies.

About

WiSound™ is dedicated to supply the international manufacturers and local brands of loudspeakers, with:

  • the state of the art Speaker Technology Platform and Products for
  • the most realistic wide sound, in every seat of every listening area.

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