Digital speaker project wins £1.25m grant

The first digital loudspeaker came a step closer to reality this month after a consortium won a e2.1m (£1.25m) grant to develop high-performance piezoelectric ceramic transducer technology.

The transducers, only 10mm in diameter, can be combined in arrays to produce small, powerful, flat speakers capable of `steering’ sound.

Powered by batteries, the speakers could replace conventional units in everything from public address systems – where one speaker could beam sound to many different areas – to hi-fi units, TV sets and mobile phones.

The consortium consists of seven EU partners, including Birmingham University and Umist, and will investigate the use of the technology, developed by 1… Limited of Cambridge, for digital loudspeakers and steered-array antennas in satellite communications.

Each transducer consists of a short, hollow cylinder formed from a helical ribbon of piezoelectric ceramic. When a voltage is applied, the cylinder deforms into a cone which propels an ultra-lightweight piston along its bore. The piston is made from an aerogel – a silica-based material with a density only a few times greater than air – and is supported on tiny bearings consisting of doughnut-shaped elastomer balloons that roll up and down the cylinder.

The aim of the project is to improve ways of fabricating the ceramic and develop suitable bearing and piston materials.

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