From the Scotsman, an article on the science of beer:
SHOWING how sound waves can help determine the perfect pint has won an Edinburgh-based biophysicist a runner-up prize in a top science competition.
Philip Jess, a PhD student at St Andrews University, faced contestants from seven UK regions in the NESTA FameLab 2007 finals.
Saturday's competition, at the Cheltenham Science Festival, aimed to find the new voices of UK science and engineering.
Mr Jess explained that when a pint of Guinness is freshly poured, tapping the side of the glass will not make a "ping" sound. Only when the drink is fully settled will that happen, because bubbles in the beer slow down soundwaves.