An apparatus comprising an earpiece and a signal processor is disclosed. The earpiece is suitable to be applied at an auditory opening of a user's ear. The earpiece comprises a speaker enabled to be supplied with an audio signal for rendering, and a microphone arranged in vicinity of the speaker to acquire a sound signal from sounds present inside the auditory opening when the earpiece is applied at the ear. The signal processor is arranged to determine whether the earpiece is applied at the user's ear by analysis of the acquired sound signal comprising any of a sound signal component of an in-ear sound type present when the earpiece is applied or an outside-ear sound type present when the earpiece is not applied. A method and a computer program are also disclosed.
