DAVID Howard has a passion for demonstrating things. Give him a gadget and he can't help picking it up, playing with it, then explaining to you how it works.

Almost as soon as photographer Paul Baker and I walk into his office at York University, he is reaching for an elegant metal and wood construction he keeps on a top shelf.

"This is a 1795 speech synthesiser," he says gleefully, tucking the contraption under his arm like a guitar and squeezing the wooden bellows at one end with his elbow. The cylindrical cloth nozzle at the other end emits a mournful, strangulated moan - and by squeezing the nozzle with his left hand he's able to change the sound from an "eeee" to an "oooo". Two different vowel sounds, in other words. "It makes you sit up and think, 'wow!'" the professor (of electronic engineering) says.

What he loves about his mechanical voice synthesiser - which is actually a modern reproduction made for him by York organist Geoffrey Coffin - is what it reveals about the inquisitiveness and ingenuity of 18th-century "natural scientists".

They wanted to understand how the human voice works, he says - and the best way to do that was to try to make a machine that would reproduce it mechanically.

His synthesiser has a bellows to act as the "lungs"; a box containing a reed to serve as the "voice box"; and the squeezable cloth nozzle to act as the throat and mouth (which together effectively act as an amplification chamber). There are even a couple of valves he can open or shut to make the "sss" and "sh" sounds of human speech.

It far from perfect: but if you become adept at "playing" it, you have an instrument that can produce at least an approximation of the human voice, he says. It fills him with admiration for the inventiveness and hunger for knowledge natural scientists who designed and built it 200 years ago.

"We could really do with some of that spirit today," he says, squeezing the bellows to emit another mournful wail.

It's a good thing that the professor has such a passion for demonstrating and explaining things: because he has just been appointed one of four men across the country charged with making engineering "sexy".

His job as an Engineering and Physical Sciences Research Council senior media fellow will be to inspire and enthuse people up and down the country - especially young people - to become interested in engineering, so that we as a nation can continue to produce the kind of engineers that made us great.

To do that, over the next three years he'll be going into schools, giving public talks and lectures, and popping up in newspapers and on TV wherever and whenever he can to try to pass on some of his own enthusiasm for the subject.

It's not going to be easy. Despite Jeremy Clarkson's heroic efforts to persuade us as a nation to adopt Isambard Kingdom Brunel as our 'Greatest Briton', engineering has a dour, dull image. It's about as sexy, in the popular imagination, as John Major's Y-fronts.

Which is completely unfair, says Prof Howard. Engineering, he insists, is about creativity; about artistry; about understanding the wonder of the way the world works and turning that understanding to the service of mankind.

Engineering is all around you, he says. The door handle you turned when you went to make a coffee; the MP3 player you listened to on your way to work; even the underpants you're wearing (Y-fronts or not) - all are the product of engineering.

"In the UK it's actually quite hard to get away from engineering," Prof Howard says. "There are possibly some places in the Lake District - but even there you'd probably see a jet passing by overhead." In fact, unless you're standing stark naked in a wilderness, it's impossible. Engineering is everywhere, and since the invention of the wheel we have used it to shape the world we live in.

If it is such a powerful, potent, creative subject, why is it so unsexy? It is partly, Prof Howard believes, because of the way at school pupils tend to be shepherded into either the sciences or the arts - with the arts tending to be more associated with creativity and self-expression than the sciences. (Though what could possibly be more creative than having designed a machine that can carry mankind to the stars? Spaceships are the product of engineering the same as everything else.) It is partly because engineering is hard, and it involves some maths. And it is partly because for some reason it just isn't seen as being glamorous. Children aged five to six, when asked to draw an engineer, tend to produce pictures of men wearing boiler suits and carrying spanners.

Because of engineering's image problem, our universities aren't attracting enough young engineers: which is bad news for the future prosperity of a nation built on its engineering know-how. In the electronic engineering department at York, Prof Howard says, students are recruited by combining engineering with more "sexy" subjects, such as music or media technology.

But it shouldn't be necessary, he says: because engineering is such a wonderful, precise, creative, eye-opening discipline. He plonks a small, beautifully-made mechanical instrument on the desk in front of me. It is, he says, a Stirling Engine: a machine invented in 1816 by Scotsman Robert Stirling to turn waste heat into power.

It operates on the principle that warm air rises. There is a little air chamber which contains a piston that does not quite fill the chamber. If the bottom of the chamber is a few degrees warmer than the top, the prof says, the warm air rises, pushing the piston up. The colder air from the top of the chamber flows out around the edges of the piston and falls to the bottom, where it in turn warms up and pushes the piston up again. The result: a constantly chugging piston. Through an arrangement of gearing, this drives a wheel - which could, in principle, be used to generate electricity.

His Stirling Engine is only tiny: but in the quality of its engineering and the precision with which it is put together, it is a thing of beauty. And it illustrates perfectly what engineering is really about, he says - which is understanding the way the world works and using that understanding to find creative solutions to problems.

Unfortunately, too many people today have got into the habit of using the products of engineering (cars, TVs, MP3 players) without wondering about how they work. We need, he says, a return to the inquiring spirit of the natural scientists who made the 1795 voice synthesiser. "Many people just don't ask the question 'why?'" he says. "We need to encourage people to ask that question."

His own area of expertise is sound and acoustics - a field in which he's a brilliant communicator. He picks up a 3-D model which looks like something a Blue Peter presenter might have knocked together out of chicken wire, and peers at me through it.

It is a series of little branches connected with other branches to form a 3-D network, and it represents the way sound travels through the air, he says. Each of the little branches represents a sound pathway. Input a sound at one side of the model, and you can follow its progress through to the other.

By making a virtual copy of this model in the shape of a building, he says, you can work out precisely on a computer the building's acoustics - and hence the best place for a musician to stand, for example. He could do that for York Minster, if he had it's internal proportions - or for Fountain's Abbey, or the proposed new Olympic stadium.

By a subtle shift of emphasis, he should also be able to do it for the human throat and mouth - so that he can model and understand, on a computer, the way we make the sounds we call talking. It would, in fact, be a modern digital version of his mechanical voice synthesiser which, when hooked up to an acoustic system and a method for 'playing' it, might allow us to create an authentic, synthesised 'voice' that has none of the machine-like quality that artificial voices have at the moment.

And that could ultimately lead to anything from computers or cars that talk to us in natural voices, to scientist Stephen Hawking being able to speak again. Engineering, you see. It's the creative appliance of science - and in the hands of a man like David Howard, it can be inspiring.

:: Some Howard highlights

Analysing the famous coughs from ITV's Who Wants To Be A Millionaire. Prof Howard was appointed by the defence team to find out whether the notorious coughs would have been audible to Major Charles Ingram as he sat in the contestant's chair. Unfortunately for the major, his acoustic research showed they would have been.

Creating a Premiership league table based on the tunefulness of fans' singing. (When he brought the table out in 2002 Southampton, then still struggling in the Premiership's lower reaches, came top.)

Proving that there really is no difference in the quality of sound produced by an all-girls' and an all-boys' choir (and hence debunking centuries of choral tradition).

Updated: 11:10 Tuesday, July 12, 2005