GB2344555A - Method for the manufacture of hearing aid shells - Google Patents
Method for the manufacture of hearing aid shells Download PDFInfo
- Publication number
- GB2344555A GB2344555A GB9827160A GB9827160A GB2344555A GB 2344555 A GB2344555 A GB 2344555A GB 9827160 A GB9827160 A GB 9827160A GB 9827160 A GB9827160 A GB 9827160A GB 2344555 A GB2344555 A GB 2344555A
- Authority
- GB
- United Kingdom
- Prior art keywords
- probe
- ear canal
- ear
- measurement
- canal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims description 4
- 239000000523 sample Substances 0.000 claims abstract description 62
- 210000000613 ear canal Anatomy 0.000 claims abstract description 41
- 230000003287 optical effect Effects 0.000 claims abstract description 12
- 239000007788 liquid Substances 0.000 claims abstract description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims abstract description 3
- 239000000835 fiber Substances 0.000 claims description 19
- 238000005259 measurement Methods 0.000 claims description 18
- 210000003454 tympanic membrane Anatomy 0.000 claims description 11
- 230000001427 coherent effect Effects 0.000 claims description 5
- 230000001681 protective effect Effects 0.000 claims description 5
- 238000001459 lithography Methods 0.000 claims description 4
- 238000012545 processing Methods 0.000 claims description 4
- 229920001971 elastomer Polymers 0.000 claims description 3
- 230000005540 biological transmission Effects 0.000 claims description 2
- 230000001419 dependent effect Effects 0.000 claims description 2
- 210000003128 head Anatomy 0.000 claims description 2
- 238000005286 illumination Methods 0.000 claims description 2
- 239000004033 plastic Substances 0.000 claims description 2
- 238000012876 topography Methods 0.000 claims 4
- 238000006073 displacement reaction Methods 0.000 claims 2
- 239000000463 material Substances 0.000 claims 2
- 238000000691 measurement method Methods 0.000 claims 2
- 230000000007 visual effect Effects 0.000 claims 2
- 238000005516 engineering process Methods 0.000 claims 1
- 239000012530 fluid Substances 0.000 claims 1
- 238000013507 mapping Methods 0.000 claims 1
- 230000002265 prevention Effects 0.000 claims 1
- 238000001228 spectrum Methods 0.000 claims 1
- 229910001220 stainless steel Inorganic materials 0.000 claims 1
- 239000010935 stainless steel Substances 0.000 claims 1
- 238000012795 verification Methods 0.000 claims 1
- 239000011780 sodium chloride Substances 0.000 abstract 1
- 150000001875 compounds Chemical class 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 229920002379 silicone rubber Polymers 0.000 description 3
- 238000003384 imaging method Methods 0.000 description 2
- 238000005266 casting Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/65—Housing parts, e.g. shells, tips or moulds, or their manufacture
- H04R25/652—Ear tips; Ear moulds
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/65—Housing parts, e.g. shells, tips or moulds, or their manufacture
- H04R25/658—Manufacture of housing parts
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/103—Measuring devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
- A61B5/107—Measuring physical dimensions, e.g. size of the entire body or parts thereof
- A61B5/1076—Measuring physical dimensions, e.g. size of the entire body or parts thereof for measuring dimensions inside body cavities, e.g. using catheters
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
- A61B8/12—Diagnosis using ultrasonic, sonic or infrasonic waves in body cavities or body tracts, e.g. by using catheters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y80/00—Products made by additive manufacturing
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Neurosurgery (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Ultra Sonic Daignosis Equipment (AREA)
Abstract
A hearing aid shell is moulded using a stereolithographic technique. Three-dimensional data of the contours of the ear canal of a user are determined using an ultrasonic or optical probe, and this data is then processed in a computer to produce a digital image file. This file is then used by a rapid prototyping stereolithography system to produce a hearing aid shell that is a precise fit for the ear canal. When the ultrasonic probe is used, the ear canal is filled with a liquid, eg saline. Details of the probes are shown in figures 2 to 6.
Description
Method for the manufacture of hearing aid shells.
This invention relates to the process of manufacturing hearing aid shells.
Hearing aid shells are currently manufactured by making an impression of a patient's ear canal by means of injecting a liquid silicon rubber compound into the canal and allowing it to solidify. This mould is then withdrawn from the ear and sent to a laboratory where a master casting mould is made that is used to cast the patient's hearing aid shell. This process is far from ideal as the silicon rubber compound shrinks during the curing stage resulting in an imperfect mould being cast. This requires that the shell be sent back to the laboratory for shape modification, a number of times, before a proper fit can be obtained. The process is also critically dependent on the skill of the individual hearing aid practitioner during the injection stage, resulting in a considerable variability of the accuracy of the impressions. Elderly patients can, in some cases, experience considerable pain due to the pressure of the silicon rubber compound on sensitive areas of their ear canal when it is injected into the ear. In addition, due to these factors, the whole process is very inefficient and time consuming, resulting in the patient waiting for a considerable period of time before receiving a properly fitting hearing aid.
This invention obviates these problems by means of the following process. This entails the use of a non-contacting, ultrasonic probe that images the shape of the ear canal cavity and relays this information to an image processing computer where a digital image file of the ear canal's shape is created. This file is then used in conjunction with a stereo lithography setup to produce the hearing aid shell that accurately fits the ear canal. Another embodiment of the invention utilises an optical probe that replaces the ultrasonic probe in the imaging of the ear canal's shape.
Specific embodiments of the invention will now be described by way of example with reference to the accompanying diagrams in which:
Figure 1 shows a block diagram of the process where the electrical signal that contains the shape information from the ultrasonic probe (1) is fed into the image processing computer (2). After processing and enhancement, multiple cross-sectional views of the ear canal can be viewed and manipulated on a monitor. A digital image file of the shape of the ear canal is then recorded onto a compact disc (3) that is used in a rapid prototyping stereo lithography system (4) to produce an accurate hearing aid shell (5).
Figure 2 shows the location of the ultrasonic probe (6) in the ear canal (7).
Here 64 transmitter/receiver transducers (8) positioned around the circumference of the probe sequentially record the cross-sectional shape of the canal acting like minature radar systems. This measurement is repeated for adjacent sections of the canal by means of a stepper motor controlled actuator (9) that withdraws the probe incrementally from the canal until the required area has been measured. The accuracy along the longitudinal axis of the ear canal depends on the size of each increment, 0.5 mm. being a typical value.
Figure 3 shows an embodiment of the ultrasonic probe head (10) where a coherent fibre optic bundle (11) is incorporated into the central region of the probe to allow the practitioner to determine a safe position of the head of the probe with respect to the tympanic membrane, (ear drum), (12), the image being viewed on a separate monitor. Illumination of the ear drum is accomplished by means of an incoherent fibre optic bundle, (15) wound around the coherent imaging fibre, (11). The ultrasonic transducer array (13) is wound around the coherent optical fibre (11) and the incoherent fibre (15)
Figure 4 shows how the ultrasonic probe (14) can be positioned correctly so that it does not come into contact with the ear canal during the measurement, by means of a guiding tube (15) located in a rubber ball (16) that is placed at the entrance to the patient's ear (17). The diagram also illustrates how the patient must lie on his side during the measurement as his ear canal must be filled with a saline solution (18) in order to ensure a good transmission efficiency of the ultrasonic waves from the probe to the wall of the ear canal and back.
Figure 5 shows a variation of the ultrasonic probe (19) that has a plastic tip (20) located at the end of the probe to allow it to rest gently against a protective cover (21) that prevents the ear drum (22) from being damaged by the end of the probe. The measurement process with this probe is exactly the same as that used for the fibre optic/ultrasonic probe described in Figure 3.
Figure 6 shows an optical probe head (23) that replaces the ultrasonic probe head (6) described in Figures 1, 2,3,4, and 5. In this embodiment, one end of the probe contains a number of individual fibres (24) positioned around the periphery of the circumference of the probe pointing normal to the direction of the probe's body (23) in the direction of the ear canal's wall (25). Each fibre acts as light conduit for an optical radar system that is attached to the other end of the fibre array (26). Either of two methods can be employed to measure the distance from the end of the fibres to the wall of the ear canal. The first method involving a light transmitter/receiver assembly (27), coupled to the other end of the fibre array (26), measures the time elapsed when a pulse of laser light is reflected from the wall of the ear canal and the second method measures the phase of a reflected wave in an interferometer (27) connected to the other end of the fibre array (26).
Both optical methods use each fibre sequentially to measure step by step the cross sectional shape of the ear canal. The measurement process is then exactly the same as that described in Figures 1, 2, and 4. The safety features embodiments described in Figures 3 and 5 can also be incorporated into the optical probe head
(23). No liquid must be injected into the ear when the optical probe is used for measurement.
Claims (8)
1. A method for the manufacture of hearing aid shells comprising of a motor actuated ultrasonic probe used to acquire the shape data of the ear canal, an image processing computer with specially developed algorithms used to filter the data, create a digital image file of the three-dimensional topography of the ear canal and control a stepper motor or a similar motor, that moves the ultrasonic probe in a series of linear displacements, allowing an area mapping of the topography of the ear canal to be obtained incrementally in steps, each step providing a tomographic slice of the canal's cross-sectional profile, a compact disc recording system, and a rapid prototyping stereo lithography system used to produce accurate hearing aid shells.
2. A new combined ultrasonic/fibre optic probe used to both acquire the shape data of the ear canal and to monitor the position of the probe within the canal without obstructing the field of view of either sensor. The fibre optic section consists of an inner coherent bundle of fibres and objective lens that relay the image of the canal to a C. C. D camera via the fibres, and an outer incoherent bundle of fibres that surround the coherent bundle and permits the illumination of the canal by an external light source that is optically coupled to the other end of the incoherent bundle. The array of ultrasonic transducers is wound around the fibre optic bundles, present technology allowing 64 equally spaced elements and their related circuitery to be located on and within the probe. Each transducer emits an ultrasonic sound impulse, normal to the body of the probe, which is then relected by the wall of the ear canal back to the transducer which now acts as a receiver. A measurement of the time elapsed between the transmission and the reception of the pulse allows the distance to be calculated as the velocity of sound in the liquid medium filling the ear is a constant known value. This measurement is repeated for all 64 transducers located around the periphery of the probe. As well as measuring the ear canal's shape, this probe allows the direct visual verification, for the practitioner, of the safe position of the end of the probe relative to the ear drum thereby preventing any damage to the ear drum by the end of the probe.
3. A rubber or other flexible material stopper located at the entrance to the ear incorporating a cylindrical stainless steel tube that runs the complete length of the stopper, through the centre, in order to act as a guide for the ultrasonic probe.
The stopper is spherical in shape or other shape consistent with establishing a non moving fit at the entrance to the ear drum in order to provide a fixed support for the probe relative to the ear. The diameter of the tube is made a little larger than the probe in order to allow the probe's smooth passage into the ear canal. This is designed to keep the probe in a fixed position relative to the side wall of the ear canal during the withdrawal of the probe by a small motor located on top of the stopper. This minimises the errors due to any relative displacements between the probe and the wall of the ear canal as the meaurement is being recorded. The small motor, which can be a stepper motor or other motor capable of being controlled by the computer, allows the probe to be withdrawn from the ear with a range of selectable, steady speeds to facilitate the three-dimensional measurement of the ear canal's surface topography by the creation of a digital image file of a series of cross-sectional measurements, of the ear canal, recorded in steps by the probe. The motor is mounted on top of the stopper to prevent any relative movement between it and the probe as the probe is withdrawn from the ear. The accuracy of the measurement of the ear canal's topography along the surface normal to the tomographic planes is dependent on the length of the incremental step between the planes during the recording phase of the measurement. The computer can be programme to alter the step size induced by the motor to give the accuracy required by the practitioner.
4. The use of a standard commercially available ultrasonic probe catheter to carry out the measurement as described in claim 1. Here a protective cover is placed over the tympanic membrane, (the ear drum), and the probe is inserted into the ear canal until it rests on the protective cover. The end of the probe is constructed so as to have a soft tip in plastic, rubber or similar biologically safe material that will not penetrate the protective cover. The technique described in claim 3 to position and control the movement of the probe is used in exactly the same way as that described for the combined ultrasonic/fibre optic probe. The visual indication of the safe position of the probe described in claim 2 is replaced by the physical prevention of this probe, in reaching the ear drum, by the protective cover.
5. The use of a saline solution or other biologically safe fluid to be poured or injected into the ear canal in order to allow the good conduction of ultrasonic sound waves from the transducers to the wall of the ear canal during the measurement procedure. The patient should lie on his side with his head supported in order that the solution does not spill out of the ear during the measurement.
6. The data in the image file of the ear canal's shape can be transmitted to the stereo lithography system by the Internet or a computer to computer telephone connection.
7. The use of this method with an optical probe in place of the ultrasonic probe to obtain the contour information within the ear canal that uses an optical radar system utilising time of flight or phase measuring interferometric techniques including the infra-red, visible, and ultra-violet regions of the spectrum. The optical probe head consists of a tube, one end of which contains many single fibres positioned side by side so that the end faces of the fibres are mounted on the periphery of the probe's body along its circumference facing the wall of the ear canal. These fibres run the full length of the probe until they are optically coupled to either an interferometer or a transmitter/receiver assembly. In the time of flight measurement, photons are emitted from each fibre in turn until a 360 degree scan is completed. The time elapsed from each fibre emitting a pulse of photons until it is detected after reflection from the wall of the ear canal is measured by a timing device in the interferometer. As the velocity of sound is known this measurement allows the distance between the fibre and the wall to be calculated. The phase measurement technique compares the phase of the reflected light wave from the ear canal wall with an internal reference wave within the interferometer that is optically coupled to the fibre sensors. The phase of the reflected component of the wave changes as the optical path between the wall and the fibre end face varies thereby allowing the cross-sectional shape of the ear canal to be measured. All other aspects of the measurement process are exactly the same as described for the ultrasonic probe in claims 1,2,3.4. and 6, for both the time of flight and the phase measurement techniques.
8. The safety features described in claims 2 and 4 to protect the ear drum can also be incorporated into the optical probe head described in claim 7.
Priority Applications (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9827160A GB2344555A (en) | 1998-12-10 | 1998-12-10 | Method for the manufacture of hearing aid shells |
| GBGB9913993.3A GB9913993D0 (en) | 1998-12-10 | 1999-06-17 | Method for the manufacture of hearing aid shells |
| GBGB9914923.9A GB9914923D0 (en) | 1998-12-10 | 1999-06-28 | Method for the manufacture of hearing aid shells |
| GB9915481A GB2344556A (en) | 1998-12-10 | 1999-07-05 | Method for the manufacture of hearing aid shells |
| EP99958399A EP1058594A2 (en) | 1998-12-10 | 1999-12-06 | Method for the manufacture of hearing aid shells |
| AU15772/00A AU1577200A (en) | 1998-12-10 | 1999-12-06 | Method for the manufacture of hearing aid shells |
| PCT/GB1999/004102 WO2000034739A2 (en) | 1998-12-10 | 1999-12-06 | Method for the manufacture of hearing aid shells |
| GB9929197A GB2348705A (en) | 1998-12-10 | 1999-12-10 | Ultrasonic device for the measurement of internal surface profiles |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9827160A GB2344555A (en) | 1998-12-10 | 1998-12-10 | Method for the manufacture of hearing aid shells |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9827160D0 GB9827160D0 (en) | 1999-02-03 |
| GB2344555A true GB2344555A (en) | 2000-06-14 |
Family
ID=10843957
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9827160A Withdrawn GB2344555A (en) | 1998-12-10 | 1998-12-10 | Method for the manufacture of hearing aid shells |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2344555A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6660208B2 (en) * | 2001-03-30 | 2003-12-09 | 3D Systems, Inc. | Detoxification of solid freeform fabrication materials |
| US8840558B2 (en) * | 2008-06-05 | 2014-09-23 | Starkey Laboratories, Inc. | Method and apparatus for mathematically characterizing ear canal geometry |
| US9433373B2 (en) | 2009-06-05 | 2016-09-06 | Starkey Laboratories, Inc. | Method and apparatus for mathematically characterizing ear canal geometry |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4961154A (en) * | 1986-06-03 | 1990-10-02 | Scitex Corporation Ltd. | Three dimensional modelling apparatus |
| US5741215A (en) * | 1993-09-10 | 1998-04-21 | The University Of Queensland | Stereolithographic anatomical modelling process |
| GB2328900A (en) * | 1997-09-03 | 1999-03-10 | Hong Kong Productivity Council | Method of moulding a model |
-
1998
- 1998-12-10 GB GB9827160A patent/GB2344555A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4961154A (en) * | 1986-06-03 | 1990-10-02 | Scitex Corporation Ltd. | Three dimensional modelling apparatus |
| US5741215A (en) * | 1993-09-10 | 1998-04-21 | The University Of Queensland | Stereolithographic anatomical modelling process |
| GB2328900A (en) * | 1997-09-03 | 1999-03-10 | Hong Kong Productivity Council | Method of moulding a model |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6660208B2 (en) * | 2001-03-30 | 2003-12-09 | 3D Systems, Inc. | Detoxification of solid freeform fabrication materials |
| US8840558B2 (en) * | 2008-06-05 | 2014-09-23 | Starkey Laboratories, Inc. | Method and apparatus for mathematically characterizing ear canal geometry |
| US9433373B2 (en) | 2009-06-05 | 2016-09-06 | Starkey Laboratories, Inc. | Method and apparatus for mathematically characterizing ear canal geometry |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9827160D0 (en) | 1999-02-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |