An apparatus comprising means for: receiving data from one or more sensors representing one or more motion characteristics of a user; determining, based on the received data, one or more time instances associated with a sound event; and controlling an active hear-through system of a wearable audio output device so as to temporarily modify, at a time of the one or more time instances, sound received by one or more input transducers associated with the active hear-through system that are output to an output transducer associated with the active hear-through system, wherein the controlling means is configured to control an active hear-through system of a wearable audio output device which comprises first and second earphones comprising respective first and second output transducers, the controlling means being configured to modify, at the one or more time instances, sound received by a first input transducer located on the first earphone independently from sound received by a second input transducer located on the second earphone, and wherein the first earphone comprises one or more first sensors for generating a first set of data representing one or more first motion characteristics, and the second earphone comprises one or more second sensors for generating a second set of data representing one or more second motion characteristics, the controlling means being configured to detect, based on a difference between the first and second motion characteristics, that a sound event is associated more with the first earphone than the second earphone, and to modify sound received by the first input transducer differently from sound received by the second input transducer. receiving data from one or more sensors representing one or more motion characteristics of a user; determining, based on the received data, one or more time instances associated with a sound event; and controlling an active hear-through system of a wearable audio output device so as to temporarily modify, at a time of the one or more time instances, sound received by one or more input transducers associated with the active hear-through system that are output to an output transducer associated with the active hear-through system, wherein the controlling means is configured to control an active hear-through system of a wearable audio output device which comprises first and second earphones comprising respective first and second output transducers, the controlling means being configured to modify, at the one or more time instances, sound received by a first input transducer located on the first earphone independently from sound received by a second input transducer located on the second earphone, and wherein the first earphone comprises one or more first sensors for generating a first set of data representing one or more first motion characteristics, and the second earphone comprises one or more second sensors for generating a second set of data representing one or more second motion characteristics, the controlling means being configured to detect, based on a difference between the first and second motion characteristics, that a sound event is associated more with the first earphone than the second earphone, and to modify sound received by the first input transducer differently from sound received by the second input transducer.