The word ‘Huh?’ appears to be universal in human languages for using when you have not caught what someone just said. It is found to have very similar form and function in spoken languages across the globe. This is one of the findings of a major cross-linguistic study by Nick Enfield with fellow researchers Mark Dingemanse and Francisco Torreira, carried out at the Max Planck Institute for Psycholinguistics in Nijmegen, the Netherlands and published in 2013. See here for full details: https://markdingemanse.net/huh/