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Fraunhofer slims down its ultra flat loudspeakers to less than one inch


September 24, 2009

Big sound from speakers that are less than one-inch thick is now possible thanks to scientists at Fraunhofer

Big sound from speakers that are less than one-inch thick is now possible thanks to scientists at Fraunhofer

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It seems the world has become obsessed with ‘skinny’ – watch your diet, exercise more and aspire to be ‘model thin’. But skinny isn't always better when it comes to speakers – good sound reproduction needs room to vibrate. However, at IFA, Fraunhofer scientists (in cooperation with Sennheiser electronic) presented a completely new concept for ultra-flat loudspeakers that still deliver full sound reproduction. What’s more, these speakers can be integrated inconspicuously on walls or in furniture because they're only 24mm thick (0.94-inch).

Today, the adage: ‘big sound needs big speakers’ is being increasingly challenged by speaker designers and manufacturers, especially as growing numbers of consumers wish to enjoy big-size movies with theater-style audio, but don’t have the necessary space in which in to do it.

Flat panel loudspeakers appeal to many listeners because they can be appreciated the opposite way to good children – 'heard and not seen'. Scientists at the Fraunhofer Institute for Digital Media Technology IDMT in Ilmenau, Germany, together with Sennheiser (the experts in headphone technology), have now developed a special, ultra-flat loudspeaker.

“This new generation offers tonal balance and acoustic pressure at a level that will even allow the use in the professional movie or concert segment in the future,” said Dr Sandra Brix from IDMT. To make this possible, Brix and her team took their inspiration from the loudspeakers of premium headphones.

“We are opening up a new application area for our highest quality electrodynamic headphone miniature loudspeakers in this alliance with Fraunhofer. Because of their compact overall depth, they are excellently suited for use in the flattest loudspeaker boxes, without any losses in tonal persuasiveness,” says Prof Dr Jürgen Peissig, head of the Signal Processing and High Frequency research department at Sennheiser electronic.

“Even if these flat panel loudspeakers are placed directly on the wall or integrated into media equipment or furniture, they can reproduce a frequency range from 100Hz-20kHz,” according to Brix. “This distinguishes our new concept from conventional flat panel loudspeakers that achieve response characteristics at this level only if kept at a certain minimum distance from the wall.”

Consequently, the ultra-flat loudspeakers are ideally suitable for multichannel systems and the IOSONO® audio system. Based on the principle of wave field synthesis, IOSONO produces a realistic and spatial sound field throughout the entire listening area by using a large number of small loudspeakers arranged in a ring.

In the future, Dr Brix says, it will be possible to use this technology in all areas that call for an integration and reproduction of sound as invisible as possible, including the automotive and aircraft construction industries.


  • Reproduction range: 100Hz to 20kHz (-6dB, half-space)
  • Sound pressure level: 88dB SPL/1 W/1m
  • Maximum sound pressure level: 94dB SPL/1m
  • Total harmonic distortion: 5% at 94dB SPL/1m (100Hz to 20kHz)
  • Maximum input power (RMS): 4W
  • Rated impedance: 15Ohm
  • Dimensions

  • Inside: (W/H/D): 700 x 500 x 12mm
  • Outside: (W/H/D): 750 x 550 x 24mm

Reproduction range: 100Hz to 20kHz (-6dB, half-space) Sound pressure level: 88dB SPL/1 W/1m Total harmonic distortion: 5% at 94dB SPL/1m (100Hz to 20kHz) Maximum input power (RMS): 4W

So we still need woofers, not to mention subs....and crossover of course. And which end is the 6 db on? I'll bet both!!

88db/W/M is rather inefficient to apply there stated 4W MAX input. These are not your home disco speakers.

5% distortion. Better be less at lesser power or the ears are going to complain pretty fast. I would have expected more from this company. I once put a teenager in a pair of their headphones. He was used to earbuds. The smile did not go away even after i took my headset back!!!!!He mumbled something about not even needing the thumper bass boost.....and just looked like back from heaven.

Is anybody familiar with this spatial repro IOSON system? like how well we can tell which horn is in the front and which in the second row with the MJQ?


I'm getting tired of these "new scientific discoveries" regarding speakers. It's an a speaker array. It looks like it uses a lot of little speakers to produce sound from a relatively high 100hz. Where's anything new? Perhaps they computer control it in an attempt to make that array sound good?

In front of me, I've $300/pr in 2001 B&W DM303s. They're solid to slightly below 50hz in my small room. Plus, they are much smaller than that big panel, though 6 or so times deeper.

This is a boondoggle. Just get good speakers from a good company and they'll be great.

Also, these speakers are also not new in the sense they cannot escape physics. The lower a frequency you want to produce, the more air you have to move. The reason this has a 100hz cutoff is that they're not pushing enough air to go lower.

Some, discovery.

Ken Creten

I wonder about the input power specification. WFS cannot be a passive system!

In principle yet, such wfs Loudspeaker wall have a brigth future, see my description of the advantages, especially in matter of air resistance adaption:


Helmut Oellers

actually - 6db at a 100hz is not bad - 100hz is lower than you think . It actually makes them in a pretty similar range as most non full range studio monitors (such as NS10s). It has potential for WFS but the delays of signals between different speakers would have to be emulated.

Augustine Leudar
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