Electrical audio signal processing systems and devices – Hearing aids – electrical – Specified casing or housing
Reexamination Certificate
1997-07-23
2001-06-19
Kuntz, Curtis A. (Department: 2743)
Electrical audio signal processing systems and devices
Hearing aids, electrical
Specified casing or housing
C381S324000
Reexamination Certificate
active
06249587
ABSTRACT:
The invention is in the field of hearing aids and concerns a hearing aid to be worn completely in the auditory canal according to the generic part of the independent claim. The inventive hearing aid is adaptable to an individual auditory canal by casting its body in an auditory canal or in a model of it which casting brings the hearing aid from a general condition into an individualized condition.
Hearing aids to be worn in the auditory canal, so called CIC-appliances (CIC for “Completely In the Canal”) like other hearing aids, substantially comprise the following components serving the hearing function: a microphone directed towards the outside of the auditory canal for reception of sound from the outside world and the transformation of this sound into electric signals, an amplifier for amplification of these electric signals, a loudspeaker facing the inside of the auditory canal for transformation of the amplified electric signals into sound and a power source (battery) for operation of the named components. The amplifier is normally designed as an integrated circuit (chip) and may, in addition to its amplifying functions have control functions and/or be programnmable. The hearing aid can additionally comprise a receiving coil for data reception for remote control of the appliance or for reception of radio or telephone signals. The hearing aid can also be designed for the reception of radio signals only and then comprise a receiving coil only and no microphone.
Furthermore a CIC-hearing aid must have supporting elements like any other hearing aid and is advantageously adapted in its form to the auditory canal of the individual wearer as precisely as possible.
The CIC-hearing aid has acoustic and aesthetic advantages compared to other bearing aids which can reach into the auditory canal but which are not worn completely in the auditory canal. The acoustic advantages of the CIC-hearing aid are mainly that the space between the eardrum and the inner end of the appliance is smaller which increases the quality of sound and reduces the necessary amplification, i.e. the energy needed for operation. The aesthetic advantages of the CIC-appliances are that the appliance is less visible.
New problems to be solved regarding CIC-appliances mainly arise from their reduced size compared to other appliances and from the fact that they are positioned deeper in the auditory canal than other appliances. A typical CIC-hearing aid has the form of an irregular cylinder with a middle diameter of ca. 6 mm and an axial length of ca. 20 mm, whereby the diameter is determined by the inner diameter of the auditory canal and the length is determined substantially by the components serving the hearing function. The outer face of the appliance is formed by a face plate with a battery opening. The outlet of the loudspeaker is arranged on the inner face which loudspeaker is positioned at a distance of ca. 3 mm from the eardrum when the appliance is worn.
According to the state of the art, structures and production methods for ITC-appliances (ITC for “In The Canal”) are used as structures and production methods of CIC-appliances also. The ITC-appliance is designed such that its inner end carrying the loudspeaker reaches into the auditory canal but a larger part is positioned in the region of the extended outlet of the auditory canal, i.e. in the external ear. This kind of ITC-appliance mostly comprises a shell as a supporting element, which shell has a cavity in which the components for the hearing function are arranged. The shell is normally produced from a hardening casting material in a mould made from a cast of an auditory canal. It is also suggested to cast this kind of shell directly in the auditory canal.
Other ITC-appliances have a skeleton to which the components serving the hearing function are fixed. The skeleton carrying the components is surrounded with a hardening material by casting, advantageously directly in the auditory canal, whereby a body having a form adapted to the individual auditory canal is formed. As this body does not have a supporting function it can be produced from a soft material which makes the hearing aid more comfortable to wear. This kind of appliance and corresponding production methods are e.g. described in publications EP-629101 and WO-92/03894.
The main difference between the CIC-appliances and ITC-appliances is, as previously mentioned, the substantially reduced size of the CIC-appliance and its position in the auditory canal which is substantially deeper. The size of the components serving the hearing function is substantially the same as with other hearing aids. The position if the CIC-appliance in the auditory canal is such that the appliance reaches from an outer part of the auditory canal, which is cartilaginous and the form of which is subject to relatively important changes when the jaws are moved, to an inner part of the auditory canal which inner part is bony, has a form which hardly changes and is extremely sensitive to touch. In particular, the CIC-appliance has no support from a part positioned in the cartilaginous elastic and relatively form-constant outlet of the auditory canal.
The named differences between the small CIC-appliances and the larger ITC-appliances lead to difficulties in the production of CIC-appliances which cannot be optimally solved by the structures and production methods taken over directly from the ITC-appliances. In order for the CIC-appliance to be able to be worn comfortably in the auditory canal even when the form of the canal changes in certain regions due to movement of the jaws and in order not to be worked out of the auditory canal by this jaw movement, the hearing aid must be adapted precisely to the form of the auditory canal and it must be sufficiently soft such that it can at least partly adapt to the changes of the form of the auditory canal. The part of the appliance positioned in the bony part of the auditory canal must fulfil similar requirements due to the high sensitivity of this part of the auditory canal.
If a shell is to be the main supporting element of a CIC-appliance it has to have a sufficient functional strength. On the other hand it should be soft for the reasons mentioned above. From this results that it requires a wall thickness which is impossible because of the small diameter of the CIC-appliance. Therefore, the softness of the shell and with it the wearing comfort has to be subordinated under the necessary strength and the necessary small size and cannot be optimal.
A skeleton for taking over the main supporting function and surrounded by a cast soft material serving the wearing comfort only and not having any mechanical functions, requires space on the inside of the appliance which space is very scarce in a CIC-appliance even for accommodation of the components serving the hearing function.
The object of the invention is to create a hearing aid which allows the miniaturization required by a CIC-appliance and which all the same offers maximal comfort to the wearer, i.e is in particular soft enough to adapt itself to the deformations of the auditory canal resulting from movement of the jaws such that these deformations do not lead to a reduction of comfort. Furthermore, the inventive hearing aid is to be able to be brought from a general condition into an individualized condition such that it is suited for an individualization directly in the ear of the wearer, an individualization which can be carried out by an auditory advisor. In particular, the appliance in its general condition is to comprise as far as possible all the components of the appliance except of the individually formed body and is not to require any further processing after the individualizing step.
This object is achieved by the CIC-hearing aid as defined in the claims which hearing aid for individualization is brought from a general condition, i.e. a condition in which it is not yet adapted to an individual auditory canal, to an individualized condition, i.e. a condition in which it is adapted to an individual auditory canal.
The inve
Aeschlimann Marcel
Clavadetscher Jurg
Barnie Rexford N.
Bernafon AG
Kuntz Curtis A.
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