Ear plug with surface electrodes

1. An ear plug insertable into a user's ear and comprising a shell with at least one electrode adapted for measuring electrical signals, said electrode being coupled to a processor for processing the measured signals, wherein:

contours of an outer surface of the ear plug are configured to individually match at least part of at least one of (i) an ear canal or (ii) a concha of a specific user such that said outer surface contours are configured to follow contours of said matched part, and

the electrode is configured, prior to insertion of said ear plug into said ear, to individually match said part such that an electrode contact surface of said electrode to contact the concha or ear canal of the user is shaped to match the contour of a part of the ear canal or concha to be contacted by said electrode.

2. An ear plug insertable into a user's ear and comprising a shell with at least one electrode adapted for measurement of electrical signals, said electrode being coupled to a processor for processing the measured signals, wherein said electrode has an electrode contact surface for contacting an ear contact surface of at least one of an ear canal and concha of a person during said measurement, wherein said electrode contact surface is shaped, prior to insertion of said ear plug into said ear, to match a contour of said ear contact surface of a specific person.

3. The ear plug according to claim 1 , wherein said electrode contact surface is shaped to follow said contour based on contour measurements taken from the ear canal of said person.

4. The ear plug according to claim 1 , wherein said electrode contact surface is not planar.

5. The ear plug according to claim 1 , comprising a recess in which said electrode is mounted, a bottom surface of the recess following the contours of the outer surface of the ear plug.

6. The ear plug according to claim 5 , wherein the electrode is held in the recess by at least one of: a close fit between the electrode and the recess, at least one convexity on the electrode corresponding to at least one concavity provided in the recess, and an adhesive.

7. The ear plug according to claim 5 , wherein the electrode is made of an electrically conductive flexible material.

8. The ear plug according to claim 1 , wherein the electrode is a polarizable electrode made of a material comprising at least one material selected from the group consisting of stainless steel, platinum-iridium, silver, titanium, platinum and tungsten.

9. The ear plug according to claim 1 , wherein the electrode is a non-polarizable electrode.

10. The ear plug according to claim 1 , wherein the electrodes covers an area of at least 1 mm 2 , and no more than 30 mm 2 .

11. The ear plug according to claim 1 , wherein said ear plug is a hearing aid ear plug having a sound presentation component for presenting sound from a hearing aid to said ear canal of said user.

12. The ear plug according to claim 1 , wherein said electrical signals are brain wave signals and said processor is a processor for processing of said brain wave signals to provide information for detecting a medical condition of the user.

13. A hearing aid comprising a microphone, a hearing aid signal processor, and an ear plug for presenting processed sound from said hearing aid signal processor to an ear canal of a user, wherein said ear plug is an ear plug according to claim 1 .

14. A method of producing an ear plug according to claim 1 , the method comprising the steps of, tracing the shape of a part of at least one of the user's ear canal and concha, converting the traced shape into a digital form such as a three dimensional computer model, and building the ear plug based on the computer model by means of a computer controlled production process such that contours of an outer surface of the ear plug are configured to individually match said shape, wherein said electrode is placed individually according to the shape of the user's outer ear, and wherein a surface of said electrode to contact the concha or ear canal of the user is shaped to follow the contour of a part of the ear canal or concha to be contacted by said electrode.

15. An electrode for use in a device for measurement of electrical signals from a location in an ear canal of a person, said electrode having a contact surface for contacting a surface of said ear canal at said location during said measurement, wherein said contact surface of said electrode is shaped, prior to insertion into said ear canal, to match the contour of said surface of said ear canal of said person to be contacted by said contact surface.

16. The electrode according to claim 15 , wherein said contact surface is not planar.

17. The electrode according to claim 15 , wherein said electrode contact surface is shaped to follow said contour based on contour measurements taken from the ear canal of said person.