Mr Kon, from London, is now suing Wim Hof's company – Innerfire BV – for up to £250,000, claiming that it failed to provide 'appropriate' warning of the tinnitus risk. Tinnitus cases have shot up by 50 per cent in the past two decades, research suggests, with experts blaming modern lifestyles. According to Mr Kon, however, the technique – which involved 'hyperventilating' and before repeatedly holding his breath – resulted not in better health but 'sudden onset tinnitus'. However, the hearing was told that Mr Kon was in fact aware of the risk of tinnitus before he purchased the video course. Tinnitus cases have shot up by 50 per cent in the past two decades, research suggests, with experts blaming modern lifestyles.