You are on a train with someone who needs to give you some urgent, secret information. He dares not speak above a whisper, but there is too much noise for you to make out what he is saying - two people behind you are talking loudly and the train is rattling non-stop. So, you activate a small device in your ear and, suddenly, all you can hear is the sound of the voice you want to hear.

The device does not yet exist, but scientists at Southampton University's Institute of Sound and Vibration Research have taken an important step in that direction. They have come up with an "active sound control" system, which can be fitted to an open window to screen out unwelcome noise.

The system uses loudspeakers to send out sound waves on the same frequency as those coming in, but following a different pattern which cancels them out. The result, says the team's leader Professor Stephen Elliott, is almost as good as shutting the window.

Silence has become a rare and precious commodityA useful thing. The word has the same origin as "commode", the name of an old type of toilet. in a modern world which bombards us with sound, whether it is the noise from traffic and building work, or music from the radio.

Gordon Hempton, an "acoustic ecologist", spent 30 years looking for places in the US where you could experience silence for more than 15 minutes at a time during daylight hours - and found only 12.

In his book In Pursuit of Silence, George Prochnik argues that noise pollution is an environmental catastropheA great disaster. Its original meaning was a sudden turn, referring to the ending of a play. which has disconnected us from the natural world. The earliest mammals, he points out, relied on their sense of hearing to keep them alive - warning them of predators and helping them to find water.

"To flee our man-made sonic excesses," he writes, "we do everything we can to cut ourselves off from the larger environment [...]. The less we can bear to be out and about in our roaring, blasting, shattering, hyper-chattering world, the less likely we are to observe it closely enough to know what might still be done to salvage its remaining assets."

Medical experts, meanwhile, have warned that noise can seriously affect your health, triggering the release of a stress hormone which damages blood vessels. In Europe alone, it is thought to be responsible for 10,000 premature deaths, 43,000 hospital admissions, and 900,000 cases of hypertensionA medical condition also known as high blood pressure. each year.

Silence is also spiritually and creatively important. Christianity, Judaism, and Islam all attach particular significance to the silence of the desert. The Christian tradition of monasticism stems from the 3rd and 4th-Century hermits known as the Desert FathersThe most prominent was Anthony the Great, who left his wealthy family to live in the Egyptian desert in around AD270, and inspired thousands of other men and women to do the same..

The Catholic novelist Sara Maitland, who travels once a year from her remote house in Scotland to the Sinai DesertA desert in Egypt's Sinai peninsula, which lies between the Red Sea and the Mediterranean., distinguishes between two types of silence. One is "the silence of self-knowing", which involves withdrawing from the everyday world to think about what really matters to us. The other is "the silence of self-emptying", in which we forget ourselves in order to communicate with God.

Some say no. Humans are social creatures, and society cannot exist without sounds. We need to communicate with each other, construct buildings to live and work in, and use mechanised transport to travel long distances. Many people find silence oppressive and frightening, and noise is valuable in telling us what is happening: electric cars, for example, are dangerous because you cannot hear them coming.

Others argue that noise is one of the most stressful things in life. It prevents our bodies from getting the rest and sleep they need, and our brains from thinking properly. As a result of the pandemic, there are many more people working from home, and they need to be able to concentrate. We are not forced to look at things we do not want to, so why should we be made to listen to unwelcome sounds?

Commodity - A useful thing. The word has the same origin as "commode", the name of an old type of toilet.

Catastrophe - A great disaster. Its original meaning was a sudden turn, referring to the ending of a play.

Hypertension - A medical condition also known as high blood pressure.

Desert Fathers - The most prominent was Anthony the Great, who left his wealthy family to live in the Egyptian desert in around AD270, and inspired thousands of other men and women to do the same.

Sinai Desert - A desert in Egypt's Sinai peninsula, which lies between the Red Sea and the Mediterranean.