Is silence golden? Patrick Shen’s meditative documentary certainly makes a case for it as a rare and precious commodity. In a frantic, jangled world where every inch of head-space feels under attack from noise – of traffic, of building work, of people yammering on their mobiles – the need for silence is becoming not merely a matter of etiquette but of mental health.

The day after I saw this film I happened to be travelling on a Virgin train, seated as usual in Coach A, the “quiet zone”, where passengers are asked to refrain from using electronic devices. These days it seems a small consideration, that one carriage of quiet, yet within minutes you could hear the trill of a phone, a voice piping up – and my stress level with it.

Shen sets the mood by opening on a noiseless montage of images – a lone tree in a cornfield, reflections in a pond – that lasts 4 minutes and 33 seconds. This is an homage to John Cage’s silent composition 4’33”, an avant-garde provocation when first performed in the 1950s. Today it sounds almost visionary.