Standing only 130mm high, the Targus Speaker Book is an iPod or MP3 player speaker set with a folding design that takes audio through a 3.5mm jack socket.
Back in the 1990s, the MOD's research laboratory was investigating ways to reduce noise levels in aircraft cabins. One method under investigation was to vibrate the lining material in anti-phase to the noise inside – a technique similar to that used in noise-cancelling headphones – but unfortunately the researchers ended up just making more noise than before they started. This accident lead to the development of a speaker technology that would eventually see the light of day under the name NXT.
'Distributed mode loudspeaker' is the name of the game, using a small 'exciter' to vibrate a flat panel such as a piece of plastic or card. Since a speaker could be readily and cheaply mass produced, the NXT company spent a lot of time and effort in securing patents on its designs, fearful of a flood of copy-cat designs that would undermine all its R&D efforts.
Scroll forward a decade, and we find the technology never really took off in the consumer market as was hoped. It is possible to find speakers-as-wall-paintings using NXT principles, but the commercial products were often far from the full-range hi-fi sound hoped for.
Yet NXT can work, even in relatively small panels such as the Targus Speaker Book. Standing only 130mm high, this folding design takes power from four AAA batteries, or can be powered from a laptop's USB port. Audio is fed in through a 3.5mm jack socket, accessible when the 'book' is opened, with a volume thumbwheel just above.
Sound quality is quite impressive for the size – we weren't expecting much bass so were not disappointed. But what you do get is a clear and open sound that is slightly delocalised from the two panels – a signature of the NXT sound. The stereo soundfield is not exactly huge but the overall effect is more than good enough to allow for music playback that is both louder and clearer than you'd expect to find from most laptop speakers. And that's all we're asking for from the Targus Speaker Book and similar units.