N’Bass Virtual Back Volume technology boosts mobile sounds by doubling air volume in loudspeaker

February 20, 2012 // Julien Happich

Knowles Sound Solutions has launched a sound enhancing technology to increase the acoustic performance in consumer devices with small form factors. N'Bass stands for “enhanced bass“ and enables the smallest possible acoustic designs in smart phones, tablets and other portable media devices.

The patent pending N‘Bass Virtual Back Volume technology is a custom-developed material which increases the back volume seen by the loudspeaker by up to 100 %. It provides either better acoustic performance – specifically more bass – or smaller loudspeaker box designs while keeping the same performance. N‘Bass also facilitates the usage of bigger loudspeakers, thus providing superior sound performance within the same gross application volume.

Similar to a sponge, 2 grams of the N'Bass material have a surface area of about a football field. As Knowles Sound Solutions’ Head of Global Product Management, Mark Hannah describes it, “the material adsorbs the air in the sealed loudspeaker box, acting as an analogue pressure sucker and making it easier for the membrane to vibrate at full amplitude for when it is needed most, at the lower bass frequencies”. Typically, the small back volumes used in mobile devices (due to space constraints) tend to increase back pressure, hence limiting the speaker membrane’s inward amplitude and affecting the bass frequencies. The material desorbs the air molecules when the membrane vibrates out of the speaker box. This virtually increases the available back volume for the loudspeaker and using this technology, the company has measured a difference in the resonance frequency of about 150Hz, with a sound pressure level-boost below resonance frequency of approximately 3dB compared to standard loudspeaker boxes.

The material, which took over two years to develop, is non-conductive and has no negative influence on antenna performance. The first smartphones to incorporate the technology have recently been launched by tier-1 handset OEMs and are currently in mass production. Knowles is currently the only supplier who offers this specific technology for miniaturized loudspeaker systems.

Visit Knowles Sound Solutions at www.knowles.com

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