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1. WO2020160674 - PROCÉDÉ ET DISPOSITIF POUR DÉTERMINER LA TAILLE D'UN CONDUIT AUDITIF

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

METHOD AND DEVICE FOR DETERMINING AN EAR CANAL SIZE

Cross-Reference to Related Applications

[0001 ] The present patent application claims the benefits of priority of United States Provisional Patent Application No. 62/801 ,891 , entitled“METHOD AND DEVICE FOR DETERMINING AN EAR CANAL SIZE” and filed at the United States Patent and Trademark Office on February 6, 2019, the content of which is incorporated herein by reference.

Field of the Invention

[0002] The present relates to methods and devices for ear canal size determination and more particularly to methods and devices for determining ear canal size in order for selecting an adapted earplug or earpiece.

Background of the Invention

[0003] The human ear canal shapes and dimensions are unique to each individual and despite recent advances in 3D scanning, determining an exact geometry of the ear canal is still a challenge.

[0004] In general, an intra-aural hearing protector size and shape is selected according to an estimation of the person's ear canal size. Various tools have been developed to estimate an ear canal size, such as an ear canal and concha gage, that allow to approximately assess the dimensions of a specific ear canal in order to recommend an approximately matching earplug size.

[0005] The proper selection of a worker’s or user earplugs is critical as earplugs being too small or too large will lead to attenuation and comfort issues. In order to cover a range of ear canal sizes, earplug manufacturers generally offer their products in a variety of sizes with different diameters or/and lengths. Past studies have shown that the human ear canal size and shape varies significantly amongst individuals. There are now several different technical solutions that can capture the precise geometry of the ear canal, in addition to the traditional ear impression taken by an audiologist and that can be 3D scanned. Optical methods, ultrasound images, and computed tomography imaging have been used to successfully reconstruct individual ear canal geometries. These research methods work

with great accuracy; however, each ear canal geometry reconstruction proves to be a cumbersome task in terms of time and resources and is not often feasible in situ.

[0006] A limited number of tools - such as a concha gage - exists to select earplugs that are size-suitable. Referring to FIG. 1 , some of the tools developed in the early 1970s to estimate the diameter at the ear canal opening and to help select an apt earplug are shown. One category of these tools is sometimes the earplug itself (see sections a) and b) of FIG. 1 ). Such methods still involve trying several devices having different sizes and discarding the devices that do not fit properly. Another tool, such as the one shown in section c) of FIG. 1 , seems to be the only generic tool available and having multi sizes. Such tools were developed about 50 years ago and no scientific data about such development and design are available in the literature.

[0007] Furthermore, with devices having a plurality of proposed earplug sizes, the number of divisions needed to correctly cover the range of ear canal geometries is unknown. The tool shown in section c) of FIG. 1 is also known as the Eargage®. Such tool may be used for multi-sized earplugs. Flowever, such tool is not adequate for classification. Also, the. circular shape of the Eargage® has a potential risk of distorting or wrongly measuring a predominantly elliptical ear canal.

[0008] There is thus a need for a tool to estimate the ear canal opening size to correctly preselect the earplug size for a specific user.

Summary of the Invention

[0009] The aforesaid and other objectives of the present invention are realized by generally providing method and device for determining an ear canal size.

[0010] In one aspect of the present invention, a method for determining an ear canal size of a user is provided. The method comprises measuring a cross-section perimeter of the little finger of the user at a predetermined distance from base of the little finger of the user, the measured cross-section perimeter of the little finger determining the cross-section perimeter of in the ear canal.

[001 1 ] The predetermined distance from the base of the little finger of the user may be between 2/3 and 9/10 of the length of the little finger. The determined cross-section perimeter may be between the opening the ear canal and 1/4 to ½ of the length of the ear

canal. The measured cross-section perimeter of the little finger may be between 20 mm and 50 mm from the base of the little finger. The measured cross-section perimeter of the little finger may further be about 35 mm from the base of the little finger. The determined cross-section perimeter of the ear canal may be between 4 mm and 8 mm from the opening of the ear canal. The determined cross-section perimeter of the ear canal may be about 6 mm from the opening of the ear canal.

[0012] Measuring a cross-section perimeter of the little finger of the user may further comprise inserting the little finger through a cavity and identifying the measured cross-section perimeter of the little finger when pressure force sensation is the same around the little finger at an entry portion of the cavity and at the other end of the cavity. The other end of the cavity may be a bottom portion of the cavity. The method may further comprise inserting the little finger through a plurality of cavities having each different diameters, wherein the measured cross-section perimeter of the little finger is identified by the diameter of the cavity in which the little finger is inserted when the pressure force sensation is the same around the little finger at an entry portion of the inserted cavity and at the other end of the inserted cavity.

[0013] In another aspect of the invention, a method for comparing geometry of a finger profile to an ear canal profile is provided. The method comprises measuring the cross-section perimeters of the finger of a plurality of individuals at fixed first intervals, associating the first intervals along a z-axis of the finger, measuring the cross-section perimeters of the ear canal of the plurality of individuals at fixed second intervals, associating the first intervals along a s-axis of the ear canal, calculating a coefficient R2 based on linear regressions between the cross-section perimeters of the ear canal and of the finger for each individual, computing an associated regression coefficient corresponding to the cross-sectional perimeters of the finger and identifying the highest correlation coefficient zone for the individuals.

[0014] Measuring the cross-section perimeters of the finger ma further comprise molding the little finger using a moldering substance, forming a replica of the mold, digitizing the replica and discretizing the geometries of the digitized finger. Molding the finger may further comprise placing strips of plaster around the finger to make a mold of individual profile of the finger. Forming a replica of the mold may further comprise filling the mold with rubber silicone to produce a replica of the finger. Digitizing the finger may further comprise scanning the finger to obtain a mesh representing the entire geometry of the replica. The method may comprise scanning the finger using a 3D scanner. The mesh may be a cloud of geometric points. Discretizing the geometries of the finger may further comprise converting the mesh into a sequence of a predetermined length step cross sections oriented along a z-axis.

[0015] Measuring the cross-section perimeters of the ear canal may comprise molding a custom earplug in the ear canal, forming a replica of the mold, digitizing the replica and discretizing the geometries of the digitized ear canal. Molding the ear canal may further comprise placing strips of plaster around the ear canal to make a mold of individual profile of the ear canal. Forming a replica of the mold further may further comprise filling the mold with rubber silicone to produce a replica of the ear canal. Forming a replica of the mold may further comprise instantly expanding a generic earpiece directly in the ear canal through injection of silicone inside an expandable earpiece. Digitizing the ear canal may further comprise scanning the ear canal to obtain a mesh representing the entire geometry of the replica. The method may comprise scanning the ear canal using a 3D scanner. The mesh may be a cloud of geometric points. Discretizing the geometries of the ear canal further may comprise converting the mesh into a sequence of a predetermined length step cross sections oriented along a z-axis. Discretizing the geometries of the ear canal may comprise using two radial planes defining a curvilinear axis with an average step having a predetermined length between each slice.

[0016] In yet another aspect of the invention, an earplug finger-gage device for a user, the device comprises a casing, the casing comprising a plurality of side cavities, each cavity having same predetermined depth and a first opening having a diameter differing from one another and being adapted to receive a finger, wherein the size of a cross-section of the finger is selected when pressure against the cavity is neither too tight nor too wide to be felt against the cavities, the size of the cross-section being indicative of the size of an earplug fitting in the ear canal of the user. Each cavity may comprise an abutment adapted to receive tip of the finger. The device may further a finger length assessment channel being large enough to accommodate a range of finger sizes and comprising a ruler. The assessment channel may comprise an abutment adapted to receive tip of the finger. Each

cavity may comprise a second opening. The second opening may have a diameter being lower than the diameter of the first opening. The device may be made with transparent material or with perforated material.

[0017] An anthropometric study was conducted to evaluate if the size of a fingertip is proportional to the ear canal size of the same person.

[0018] The study involved identifying a zone in the little finger that is generally proportional to the ear canal size of the same person. The identified zone is a same zone for a large group of people and can be used as a predetermined measurement zone for assessing the ear canal size. Notice that the identified zone can vary depending on gender, age, ethnical origin, life style, etc. Moreover, a plurality of discreet zones can be identified for assessing the ear canal size. Also, each identified zone can have a certain range in order to accurately assess the ear canal size.

[0019] A method for establishing an ear canal size involves measuring at least one predetermined zone of the little finger. The method further involves, determining an individualized ear canal size according to the measurement. The ear canal size can be determined based on a predetermined linear regression model, or based on any other suitable model.

[0020] The measuring of the at least one predetermined zone of the little finger can be performed by scanning the little finger, by inserting the little finger into a gage, or by using any suitable little finger measurement tool.

[0021 ] The features of the present invention which are believed to be novel are set forth with particularity in the appended claims.

Brief Description of the Drawings

[0022] The above and other objects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which:

[0023] FIG. 1 presents prior art devices adapted to select earplugs that are size-suitable. [0024] FIG. 2 presents a geometry comparison between a little finger and an ear canal of a same person, based on a study involving eight human participants, according to one embodiment;

[0025] FIG. 3 presents a graph of ear canal cross-sectional measurements and a graph of little finger cross-sectional measurements according to corresponding axial positions and an identified correlation zone that is marked in a dashed line on each graph, based on the study of Figure 1 , according to one embodiment;

[0026] FIG. 4 presents a graph of ear canal and little finger cross-sectional measurements and associated individual correlation coefficients, according to the measurements of Figure 2, the individual correlation coefficients have a mean value of 0.87 ±0.1 , according to one embodiment;

[0027] FIG. 5 presents a graph identifying a little finger measurement zone according to group correlation coefficients obtained by scanning cross-sectional ear canal perimeters of a group of individuals and computing the associated regression coefficient to corresponding finger cross-sectional perimeters, the highest correlation coefficient zone for the group of individuals being identified by a rectangle, according to one embodiment; and

[0028] FIG. 6 is an illustration of an embodiment of an earplug finger-gage device, according to the principles of the present invention.

[0029] FIG. 7 is an illustration of another embodiment of an earplug finger-gage device, according to the principles of the present invention.

[0030] It will be noted that throughout the appended drawings, like features are identified by like reference numerals.

Detailed Description of the Preferred Embodiment

[0031] A novel method and device for determining an ear canal size will be described hereinafter. Although the invention is described in terms of specific illustrative embodiment(s), it is to be understood that the embodiment(s) described herein are by way of example only and that the scope of the invention is not intended to be limited thereby. [0032] Referring now to FIG. 2, a comparison of geometry of ear canal and finger profiles is illustrated. The cross-section perimeters of the ear canal and of a finger, preferably the little finger, of a user are measured along an axis or along a plan using any measurement method known in the art. The geometric correlation coefficient (R2) of an ear canal to a finger of a user is computed based on the said measured cross section perimeters measurements of the ear canal and finger. The group geometric correlations (Group R2) are computed by scanning group cross section ear canal perimeters and by computing the associated regression coefficient to each group finger cross section perimeters.

[0033] The method for comparing geometry of a little finger profile 100 generally comprises molding the little finger using plaster or any other similar substance 1 10, forming a replica of the plaster mold of the pinky finger 120, such as using a silicone or other similar substance mold, digitizing the silicone mold 130, such as 3D scanning the mold and discretizing the geometries of the pinky finger 140.

[0034] The step to molding the little finger 1 10 may further comprise placing strips of plaster around the little finger to make a mold of the individual profile of the finger. The step to form a silicone mold 120 may further comprise filling the plaster mold with rubber silicone to produce a replica of the pinky finger. The steps to digitize the pinky finger 130 may further comprise using a scanner, such as a 3D scanner to obtain a mesh, such as a cloud of geometric points, representing the entire geometry of the replica. The step to discretize the geometries of the pinky finger 140 may further comprise converting the mesh into a sequence of a predetermined length step cross sections oriented along the z-axis. In some embodiments, the step has a length of 1 -mm.

[0035] The method for comparing geometry of an ear canal profile 200 generally comprises molding a custom earplug in the ear canal using plaster or any other similar substance 210, forming a silicone or other similar substance mold of the ear canal from the plaster mold earplug 220, scanning the silicone ear canal mold 230, such as 3D scanning the mold and discretizing the geometries of the ear canal 240.

[0036] The steps 210 and 230 may be similar to the steps 1 10 and 130 but adapted to use the custom earplug. The step to form a silicone mold 220 may further comprise instantly molded using a known process, such as the SonoFit process. The SonoFit process generally comprises expanding a generic earpiece directly in the ear canal through the

injection of a medical grade silicone inside an expandable earpiece. The step to discretize the geometries of the ear canal 240 may comprise using two radial planes defining a curvilinear axis (such as s-axis) with an average step having a predetermined length between each slice. In some embodiments, the predetermined length is about 0.5 mm.

[0037] Referring now to FIG. 3, a graph of example ear canal cross-sectional measurements 300 and a graph of little finger cross-sectional measurements 320 are shown according to corresponding axial positions, either along a s-axis or a z-axis, and an identified correlation zone. The identified correlation zone is marked in a dashed line 302 and 322 on each graph, based on the study of FIG. 2, according to one embodiment.

[0038] To obtain the data and zones of correlation calculation, all the discretized geometries of a number of users are aligned along the z-axis for the pinky finger and along the s-axis for the ear canal. The perimeters of each little finger and ear canal cross-sections are measured for all the users and are associated to a position along the z-axis or the s-axis, respectively. These data are plotted in FIG. 3 for an exemplary eight participants and sixteen associated geometries, which helped to identify the zones where data was available for all the participants (to the left of the dashed line on each chart of FIG. 3) together with a highlighted zone 304 and 324 where the profiles are suitable for linear regression calculations.

[0039] As an example, the tip of the finger where cross-section perimeters rapidly tend to 0 were not considered in the correlation calculations. A trend is observable in FIG. 3 in which the order between the largest and smallest cross-section perimeters at position near 0, on both the s- and z-axes, is almost the same, implying that a large ear canal opening will be associated to a large pinky finger. The collected data is used to perform individual and group correlation calculations. For the individual correlation, the coefficient R2 is calculated based on linear regressions between ear canal and pinky finger cross-section perimeters. For the group correlations, the evolution of coefficient R2 was calculated by scanning group cross-section perimeters of the ear canals and computing the associated regression coefficients to each group pinky finger cross-section perimeters.

[0040] Referring now to FIG. 4, a graph of example cross-sectional measurements 400 and associated individual correlation coefficients of an ear canal and little finger 420 are shown as a relation to the measurements of FIG. 3. In such an example, the individual correlation coefficients have a mean value of 0.87 ±0.1.

[0041 ] The results for the individual correlation calculation together with the individual linear correlation coefficient R2 are presented in FIG. 4. In some examples, the degree of linearity between the two parameters is relatively high, ranging from about 0.65 to 0.96. In approximately 50% of the set of data, the value of R2 is higher than 0.9. These results suggest that it is possible to estimate the cross-section perimeter of the ear canal based on a precise knowledge of the little finger geometry combined to the most adequate linear model selected from several linear regression models. Even if this linear model is unique to an association between an ear canal and a pinky, an abacus may be established based on the said exemplary data in order to select the most appropriate linear relation and estimate the ear canal cross-section perimeters. Understandably, such method may be used with any number of participants, the higher number of participants increasing the database and thus refining the number and the coefficient of linear models to use to cover the range of interindividual variations.

[0042] Referring now to FIG. 5, a graph identifying an exemplary little finger measurement zone according to group correlation coefficients is shown. The group correlation coefficients may be obtained by scanning and measuring cross-sectional ear canal perimeters of a group of individuals. The associated regression coefficient to corresponding finger cross-sectional perimeters are then computed. The highest correlation coefficient zone for the group of individuals are shown in the graph of FIG. 5 by a rectangle.

[0043] A matrix of correlation coefficients is evaluated by scanning the group cross-section perimeters of the sixteen ear canals at different locations along the s-axis and the degree of linearity was verified by evaluating R2 at every single location on the z-axis and for the entire group data of the pinky cross-section perimeters. The cross-section perimeters of the ear canal (as a function of coordinate s) and of the little finger (as a function of coordinate z) and for all the participants (n = 16) are defined respectively as:


[0044] The correlation coefficient at a fixed coordinate s and z is then expressed in terms of the covariance of Cf(z) and Ce(s)


[0045] where and aCe(s) denote the standard deviation of Cf(z) and Ce(s), respectively. R2 is then evaluated for all the possible combinations of s and z, as shown in FIG. 5.

[0046] Still referring to FIG. 5, the exemplary graph generally shows that the correlation coefficient R2 reaches a maximum value, of around 0.7, in two particular zones. The zone highlighted with a dotted-line may be considered carefully, as such zone corresponds to a zone relatively close to the ending of the custom earpiece, an area that sometimes particularly differ from the real shape of the ear canal at this position.

[0047] As such, in the context of selecting an earplug size, it may be more advisable to select a zone closer to the opening of the ear canal. The zone highlighted in solid lines is generally the cross-section perimeter of the ear canal for an area comprised between its opening to approximatively 6 mm and for the pinky finger cross-section perimeter, around 35 mm from the base of the pinky. Understandably, the present values are examples and may be adapted based on the size of the pool of candidates to be measured.

[0048] Referring now to FIG. 6, a cross-sectional view of an embodiment of an earplug finger-gage device 500 is illustrated. The earplug finger-gage device 500 has a plurality of side cavities (502a, 502b and 502c), each cavity having the same predetermined depth (D). The plurality of cavities (502a, 502b and 502c) each have a diameter (d1 , d2 and d3) that differs one from another and allows to assess finger equivalent diameter at the predetermined depth (D). The device 500 is shaped to allow insertion of the little finger until it touches a bottom portion 504 of one of the cavities (502a, 502b or 502c). An associable cavity (502a, 502b or 502c) is identified when the pressure force sensation is the same around the finger at an entry portion 506 of the cavity (502a, 502b or 502c) and at the bottom portion 504. However, if the inserted finger feels loose - no side pressure while touching the bottom portion 504 - when in the cavity, the cavity is too large and is not associable to the finger. If the finger cannot enter the cavity or is unable to touch the bottom portion 504, the cavity is too small and is not associable to the finger. The identified associable cavity diameter is indicative of the finger diameter at the at least one of the predetermined zones.

[0049] Moreover, according to one embodiment, the device 500 may have a finger length assessment channel 508. The assessment channel 508 is large enough in diameter to accommodate a range of finger sizes or all finger sizes. The assessment channel 508 is shaped to allow complete insertion of the little finger inserted up to abutment of the interdigital fold with the channel edge of the entry portion 510. According to one embodiment, the channel 508 is covered with a clear cover or is perforated to enable viewing of the finger. The device has a ruler 512 (shown here in a dashed line), by matching the tip of the finger to a graduation of the ruler, a finger length is thereby determined.

[0050] The device 500 is shaped to allow insertion of the little finger until it touches a bottom portion 504 of one of the cavities (502a, 502b or 502c). An associable cavity (502a, 502b or 502c) is identified when the pressure force sensation is the same around the finger at an entry portion 506 of the cavity (502a, 502b or 502c) and at the bottom portion 504. However, if the inserted finger feels loose - no side pressure while touching the bottom portion 504 - when in the cavity, the cavity is too large and is not associable to the finger. If the finger cannot enter the cavity or is unable to touch the bottom portion 504, the cavity is too small and is not associable to the finger. The identified associable cavity diameter is indicative of the finger diameter at the at least one of the predetermined zones.

[0051 ] Referring now to FIG. 7, a perspective view of another embodiment of an earplug finger-gage device 700 is illustrated. The earplug finger-gage device 700 has a plurality of side cavities 702a, 702b, 702c, 702d and 702e, each cavity having the same predetermined depth (708). The plurality of cavities 702a, 702b, 702c, 702d and 702e each have a first diameter (d1 , d2, d3, d4 and d5) forming entry points 706 of fingers. Each first diameter (d1 to d5) differs one from another and allows to assess finger equivalent diameter at the predetermined depth 708. The cavities 702a, 702b, 702c, 702d and 702e each comprises a second diameter (d’1 , d’2, d’3, d’4 and d’5) forming exit points 704 for fingers. In some embodiments, each second diameter or some of the second diameters (d’1 , d’2, d’3, d’4 and d’5) may be smaller or may have a smaller area than each respective first diameter (d1 , d2, d3, d4 and d5) in order to press against the introduced finger. In other embodiments, each second diameter (d’1 , d’2, d’3, d’4 and d’5) may be respectively and substantially equal to the first diameters (d1 , d2, d3, d4 and d5). Understandably, the number of cavities is not limited to 5 and could be adapted based on data obtained in a method to evaluate the size of an ear canal vs pinky finger having a number n of participants.

[0052] In the embodiment shown in FIG. 7, the device 700 comprises holes 706 with increasing sizes where a user may introduce a finger, such as the pinky finger. Each cavity 702a, 702b, 702c, 702d and 702e is generally shaped as a truncated cone. The depth of the device may be adapted to the users, such as be of 35mm. In use, the finger is introduced in the different holes 706 and the size is selected when a pressure neither too tight nor too wide is felt against the cavities 702a, 702b, 702c, 702d and 702e. In some embodiments, the material may be transparent to make possible verification of the contact between the tool and the skin.

[0053] While illustrative and presently preferred embodiment(s) of the invention have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.