Waterproofing mobile devices such as phones, MP3 players and cameras is becoming ever more common. But devices sporting little holes to let the sound out pose a bit of a leakage problem. Rather than potentially reduce sound quality by covering them up, Murata has produced a tiny piezoelectric speaker which is itself waterproof.

Sometimes it just can't be helped. No matter how hard you try to keep your mobile phone dry, water somehow finds a way to sneak in and wreak havoc with internal components. Manufacturers are taking measures against liquid infiltration - of the 50 or so mobile phones launched in Japan this year, almost a quarter have received some sort of waterproofing, but this is sometimes at the expense of performance.

Case in point - the dynamic speaker inside your mobile phone, media player, digital camera, e-Reader and so on. Waterproofing such audio devices usually involves covering sound output holes with waterproof sheets, to prevent exposure to the moisture that can lead to component erosion damage. Unfortunately, this form of protection often results in a reduction in the quality of the output. It also adds to production costs.

Japan's Murata has come up with a 0.9mm thick piezoelectric speaker which is IPX7 waterproof, meaning that it should be able to easily cope with temporary immersion underwater or even being hit by a jet of water, and does so while maintaining the intended audio quality. More importantly perhaps, the new speaker negates the need for extra production costs incurred by including waterproof sheeting.

The tiny speakers have already gone into production and are likely to cost in the region of JPY250 (about US$2.72) per unit.