In general, in one aspect, a method performed by one or more processes executing on a computer systems includes receiving an audio signal comprising a range of audio frequencies including high frequencies and low frequencies, converting a first portion of the range of audio frequencies into haptic data, shifting a second portion of the range of audio frequencies to a different range of audio frequencies, and presenting at least one of the converted first portion and the shifted second portion to a human user. Other implementations of this aspect include corresponding systems, apparatus, and computer program products.