New 'silent camera' apps cause plague of voyeurism in Japan - and some are on sale in West 60 per cent rise in illicit photography Apps let users take photos - but only show innocent-looking emails on screen Silent camera apps already on sale in West By Rob Waugh Last updated at 12:55 AM on 3rd January 2012 Most smartphone cameras have a built-in shutter noise to prevent the camera being used to take pictures without people's consent. But a new wave of 'silent' apps - some specifically designed for voyeurism - have been blamed for a huge rise in...