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Cellphones and palmtop organisers can now play louder ring tones and MP3 music with less drain on the batteries, thanks to a new way of radiating sound from the screen. Tiny speakers sound tinny and only produce a narrow beam of sound in one direction, says Matsushita of Japan, which makes Panasonic cellphones. And while clamping a small speaker directly onto the glass panel can make the whole panel vibrate back and forth—spreading the sound more widely—energy is wasted because the sound waves also travel sideways through the solid panel. Panasonic’s answer is its Sound Window technology, which uses a…