A hearing instrument in accordance with the invention comprises an in-the-ear-canal component to be worn at least partially in the ear of a user. When the hearing instrument is worn, a remaining volume between the in-the-ear-canal component and the user's eardrum is defined. The hearing instrument includes at least one first microphone operable to convert an acoustic input signal incident on the hearing instrument into an electrical input signal, signal processing means operable to convert the electrical input signal into an electrical output signal on a signal path, and an electrical-to-acoustic converter (a receiver or a plurality of receivers with potentially different frequency characteristics). Between the remaining volume and surrounding atmosphere, a duct (such as a vent) is defined. A second receiver is in operative communication with the duct, i.e. an output directly opens out into the duct or to a sound conductor opening out into the duct. The hearing instrument further comprises a second microphone in operative communication with said duct and operable to record an error signal in said duct.