Method of fitting a hearing instrument, and impression tool

A method of fitting a hearing instrument to a user's ear, the ear including an ear canal and an eardrum, the method comprising the steps of:

• taking an impression of the user's ear canal by inserting an impression tool into the ear canal such that a remaining volume is defined between the impression tool and the eardrum, the impression tool including impression material, at least one measurement tube extending through the impression material and having a first end that opens into the remaining volume and a second end, a receiver in acoustic communication with the second end of the measurement tube, and a microphone in acoustic communication with the second end of the measurement tube;
• performing an acoustic measurement while the impression is being taken and prior to removal of the impression tool from the ear canal by
• transmitting a sound signal from the receiver through the measurement tube to the remaining volume, and
• measuring a response acoustic signal that travels from the remaining volume through the measurement tube to the microphone;
• and
• generating geometrical data of the impression.

An impression tool for taking an impression of an ear canal, the impression tool comprising:

• an impression device, selected from the group consisting of a flow stop that confines a flow of impression material within the ear canal and an inflatable element that is inflated with impression material, that is configured to be positioned within the ear canal such that a remaining volume is defined between the impression device and the eardrum;
• at least one measurement tube that extends through the impression material;
• and
• an acquisition system, including a receiver, a microphone and an electronics unit operably connected to the receiver and the microphone, acoustically coupled to the at least one measurement tube such that a sound signal emitted by the receiver will pass through the at least one measurement tube and into the remaining volume and then return from the remaining volume through the at least one measurement tube and be picked up by the microphone.