A speaker of a hearing instrument generates a sound that includes a range of frequencies. Furthermore, a microphone of the hearing instrument measures an acoustic response to the sound. A processing system classifies, based on the acoustic response to the sound, a depth of insertion of an in-ear assembly of the hearing instrument into an ear canal of a user. Additionally, the processing system generates an indication based on the depth of insertion of the in-ear assembly of the hearing instrument into the ear canal of the user.