GB2358101A - Programmable or adjustable ear-speaker, method of construction and kit of parts - Google Patents

Abstract

A programmable or adjustable audio-communication device comprising an externally contoured earplug 11 to fit into the human wearer's aural cavity. The earplug has a cavity (24, figure 2B) in which a micro-speaker 17 and programmable or adjustable circuit assembly 18 are located, either as separate components or contained in a module. A passage 14 extends from the cavity to emerge adjacent the wearer's eardrum so as to channel the output of the speaker to the eardrum. The earplug may have a secondary passage 16 or other access means between the micro-speaker/circuit assembly and connectors outside the wearer's concha. This passage is traversed by electrical conductors 20 and allows attachment to external signal providing circuitry. A method of construction for the ear-speaker, and a kit of parts for use in this method are also disclosed.

Description

2358101 "PERSONALISED, PROGRAMMABLE OR ADJUSTABLE AUD10m COMMUNICATION

DEVICES FOR HUMAN WEAR" This invention relates to audio-commun i cation devices for human wear and more particularly to what may be regarded as an ear-speaker, the output of which can be varied in frequency spectrum and amplitude, primarily intended for use in conjunction with inter-personal communication systems, as well as a kit of parts for the assembly of such devices, and methods of manufacturing them.

There are personal inter-communication systems nowadays of remarkably diverse kinds, adapted to different situations. They may involve merely line-transmitted audio-signals, or they may include radio links... but all of them of course in the end must deliver the voice or other signal to the ear of the person at the receiving end. What is more, it is obviously necessary not only that the desired signal should be clearly delivered to the recipient's ear and understood with the greatest degree of accuracy, but also that extraneous, background noise should be so far as possible excluded, since otherwise the desired signal can be altogether lost or at least so distorted by high-volume background noise that the desired message will no longer come across clearly to the recipient, possibly to the extent that it may be misunderstood with

2 perhaps even fatal consequences.

It is also a fact that repeated exposure to common place noise levels or exposure to extreme noise can cause permanent and irreversible damage to one's hearing, and this acquired hearing loss will be predominant in certain frequencies, typically in the range of from 4 to 6 kHz. It is therefore quite probable that individuals who may wish to use intercommunication devices in noisy environments will already have some degree of hearing loss, as a result of such previous exposure. This loss will cause the recipient of the signal to have additional difficulties in understanding the incoming signal.

The twin objectives of clearly delivering the desired signal whilst blocking background noise, are highly important in many kinds of situation either military or civilian in nature. The need is encountered for instance in crew-intercommunication and radio communication with base in land, sea or air fighting-vehicles, e.g. fighter andlor bomber aircraft and helicopters, tanks and armoured person ne 1 -carriers, motor torpedo boats and so on, as well as also in civilian aircraft of all sizes and kinds, both commercial and private, as well as public service vehicles such as police cars, ambulances and fire-engines, and even in taxis, racing cars and so on.

The need for clear, background-free voice-delivery is indeed selfevident, and of course over the years a number of different approaches have

3 been adopted to achieve the desired objectives.

In many military contexts, and indeed some others, the most commonlyused arrangement has until now been to provide a speaker for the desired signal located within an earmuff which (usually with a twin on the other side of the recipient's head) serves to shut out extraneous noise while delivering the desired signal outside but immediately adjacent to the wearer's aural orifice, that is to say his or her concha.

For many purposes no doubt this conventional arrangement is adequate, and it has certainly stood the test of time, being widely used today. It is however in truth inefficient, since it neither succeeds in fully excluding extraneous background noise nor does it deliver the desired signal within the ear to the very eardrum of the recipient, nor does it make allowances for the recipient's hearing levels across the audible frequency range, or their personal preferences for the desired tonal quality of the signal. Moreover this earmufftype arrangement necessarily involves a quite cumbersome contraption to be worn on the head of the signal -recipient, which may lead the latter to try to dispense with it or at least to misuse it. Also, this is a bulky contraption which does not fit well with other things, e.g. with the tightly head-hugging helmets which best afford protection to the wearer against injury in the case of any kind of crash in which the aircraft, land vehicle or sea- going vessel might become

4 involved.

So far as it is known, all existing inter-personal communication devices do not take the user's hearing levels or preferences into account. Even if such devices are able to efficiently reproduce the signal, in cases where the recipient does have impaired hearing, they will have difficulty understanding the message, as they will only hear certain parts, that is to say certain frequencies, of the output signal.

Therefore, whether always recognised or not, there has long been a need for a device which will more efficiently deliver the desired signal, which may have been altered in frequency amplitude in comparison to the initial input signal to overcome the recipient's hearing disability, to the ear of a recipient, whilst at the same time more effectively blocking extraneous background noise, however loud and intrusive.

It is an aim of this invention to furnish just such an efficient earlocated device, which will be far less cumbersome than the very conventional earmuff type, of arrangement, and will enable adjustments to the signal to be made, thus taking into account the recipient's hearing andfor personal preferences. This will therefore prove to be far more efficient, in terms of improving and enhancing the clarity of the received signal than such alternatives to the earmuff-type arrangement as have hitherto been tried out.

These objectives are now attained by providing a method and a kit of parts which make it possible to construct a device that will enable the input signal to be manipulated, in a similar manner to that which occurs in a graphic equaliser in a hi-fi system, by internal digitally programmable or manually adjustable electronic circuitry. The desired output signal (with a high degree of exclusion of extraneous background noise) will then have a greatly improved intelligibility because of the modifications to the signal's sound spectrum to suit the user's hearing levels. This signal can then be delivered within the signalreceiver's aural cavity, closely adjacent to the eardrum itself from within an earplug contoured and at best indeed tailor-made to fit the individual signalreceiver's own aural topography.

According to one aspect of the present invention there is provided a method for construction of a personalised, programmable or adjustable earspeaker assembly, adapted to fit closely within the intending signalreceiver's aural cavity, thereby excluding nearly all extraneous background noise, which however will deliver the desired digitally, electronically or manually adjusted signal to the signal-receiver's eardrum, said method comprising the steps of:

(a) filling at least the outermost parts of the signal-receiver's aural 6 cavity with a medical-grade polymerisable impression material, and initiating and continuing polymerisation thereof until it has set to a stillflexible but hard rubbery-consistency earplug; (b) removing the flexible, rubbery earplug thus formed from the intending signal-receiver's aura[ cavity and using it as a mould-former in creating a complementary mould in a moulding material, which may be known although not exclusively, as the first stage investment or mould.

(c) removing the mould-former from the resultant mould, and then casting synthetic resin plastics material, non-irritant for human epidermal and epithelial tissue, within said complementary mould, with or without mouldcores or tools adapted to form a cavity andlor passages within the resultant moulding; (d) separating, the resultant cast earplug from said complementary mould, removing any mould-cores from andlor boring out the cast earplug so as to form the first and second passages therein, said first passage extending within the earplug from that part thereof which in use will be located adjacent to the wearer's eardrum, and said second passage extending from the part thereof which emerges from the 7 wearers concha, said first and second passages both communicating with a cavity within the earplug; (e) locating a micro-speaker and it's electrical connections with programmable electronic circuitry and the said circuitry, which may be powered either by a battery cell or by connection to the source of communication signal (e.g. radio receiver) within said cavity with the speaker thereof directed along the passage towards the wearer's eardrum; (f) testing the hearing of the intended user, by means of a standard test such as those used and accredited by the British Society of Audiologists (BSA), and thereby obtaining a representation of the user's hearing levels or preferences across the audible frequency spectrum; (g) programming or adjusting the electronic circuitry of step (e) so as to compensate for any hearing deficiency or preferences detected in the test of step (f), by adjusting the amplitude of the required frequency bands in the audible spectrum.

As a sensible precaution, the method of this invention will normally and 8 desirably include the additional preliminary step of inserting a disposable pad within the aural cavity adjacent to, and able to protect the eardrum before carrying out step (a) above, and it then will of course also include the subsequent additional step, following removal of the earplug in step (b) above, of removing said pad from the aural cavity and discarding it. Such a disposable eardrum-protective pad may suitably be formed of a soft and flexible grade of open-pore polyurethane foam.

The polymerisable impression material employed in step (a) above, may suitably be a medicai-grade silicone impression resin, akin to that used in dental impressions.

The moulding material employed in step (b) above, to form the complementary mould may be of any appropriate kind, which is convenient to handle, and for instance can advantageously be a silicone material or Plaster of Paris.

The synthetic resin plastics material used in step (c) above, to cast the final earplug must of course be non-irritant for human epidermal and epithelial tissue, since otherwise it will give rise to discomfort or even worse problems in the wearer's ear when worn for prolonged periods. Subject to that proviso, it may however be any of a wide range of casting resins. It is at present 9 preferred, on a balance of availability, cost and ease of handling to use a soft silicone material, a hard acrylic resin or an addition- mix silicone resin e.g., those known by the common names Molloplast SUB (often abbreviated as'MS') or Biopore - AB (often abbreviated as 'BP') both of which are commercially available for instance from P.C. Werth Ltd of London, England It is, however, also possible for this purpose to use the ultra- hypoallergenic synthetic resin plastics based on urethane acrylate, which are highly suitable, having low moisture-absorption, and which are moreover easily handled since they are thermal ly-softening so that they become softer in the ear for excellent sealing (35 shore A) yet firmer when cool for easy insertion. Also, many other silicone based materials with, for example 40 shore or 90 shore sealing properties may be used.

The speaker and electronic circuitry, as described in step (e) above, may be secured in position in the cavity with their associated electrical connections extending from the circuitry through a second passage to emerge from the earplug outside the wearer's concha. The circuitry may also have some form of retaining wall or faceplate on which would be formed the means to insert and hold in place a battery cell. If necessary, there may also be access to the connection port(s) for communication between the programming device and the internal electronics. This may be in addition and separate to the battery drawer, or the one orifice may be used for both purposes. In the case where the power needed for the device is drawn directly from the signal source, then requirements for a battery housing would not need to be included.

According to another aspect of this invention, the mini-speaker and its associated circuitry may be manufactured into a removable module, which may be easily inserted into and removed from, a suitably shaped cavity within the earplug, rather than being permanently secured within the said earplug. This module may be formed from any appropriate material such as a hard plastic or soft silicone. The module itself may be inserted into a cavity extending from the side of the earplug which emerges from the wearer's concha. A passage would be bored into the moulding, this passage extending within the earplug from that part thereof which in use will be located adjacent to the wearer's eardrum and will communicate with the cavity used to house the said module. The module's dimensions will be sufficient to fit snugly into the pre-formed cavity, giving an air- and sound-tight fit. The cavity and module will be of such a design as to offer a secure coupling when the module is firmly in place, but with the application of a slight force the module will become free of the said cavity.

When the module is not in use within the earplug, it may be replaced in the cavity by a similarly shaped blank or filter of an appropriate soundproofing material. This will then act as a conventional noise-blocking earplug, but still 11 retaining the improved noise-reduction levels due to the tailor-made closefitting of the assembly within the user's ear.

The removable speaker-module will have a passage or hole positioned on the side to be placed into the bottom of the said cavity which will then communicate with the passage which emerges next to the wearer's eardrum. Within the module, the speaker will be positioned so that its output will be directed down this first passage. If required there may be a drawer or similar facility for insertion of a battery cell, or the required power may be taken directly from the signal source (e.g. radio receiver) via electrical connections. On the side of the module which will emerge from the wearer's concha when in place in the earplug cavity, there will be a port for connection to a computer or other programming device using appropriate programming electrical leads to adjust the output of the device. This device may have incorporated into it certain software appropriate for the programming of the chosen electrical circuitry so as to adjust the amplitude of the desired frequency bands either to compensate for the user's hearing deficiency, or in accordance with their preferences.

It may however be advantageous and is another aspect of this invention that instead of digital programming, the use of manually adjustable controls may be employed, and these may conveniently be positioned on the 12 external side of the module. Any required electrical connections to the internal electrical circuitry from the signal source, may also emanate from the module.

As will be apparent, the cast earplug must have a roughly central cavity adapted subsequently to receive the micro-speaker and associated circuitry or module containing the same. In the first instance it may also have first and second passages communicating with that cavity, the first to channel the audio signal emergent from the speaker to the wearer's eardrum, and the second to provide access for the electrical connections via which the speaker and circuitry are operated. Preferably, the second passage may take the form of a hole or passage created in the assembly's retaining wall or faceplate on the external concha side of the ear-piece. In the modular version of the device, the presence of the second passage is not necessary.

According to yet another aspect of this invention, an additional passage separate from the others may be used to ventilate the space between the end of the earplug and the eardrum, or to insert a frequency specific attenuator to control the levels of noise that the earplug will attenuate. This passage where present, will extend within the earplug from that part thereof which in use will be located adjacent to the wearer's eardrum and the part thereof which emerges from the wearer's concha.

13 The cavity and the passages may be created by use of mould-cores or tools during casting; but if the correct positioning of such mould-cores is not easy, it may be consequently preferred to form both the cavity and the necessary passages by boring them out with drills andlor reamers from the cast earplug.

The boring of the cavity and passages can generally be effected most conveniently by drilling from each end of the ear plug so that the passages meet within the earplug at what can be regarded as its mid-point. Drilling can be accomplished by the use of any suitable drilling equipment. The passage directed from the mid-point towards the wearer's eardrum can advantageously be of slightly less diameter than the other passage which extends from the central cavity to a point external of the wearer's ear, so that at the point where the two passages meet there is created a seating upon which the subsequently inserted micro-speaker can rest and be located thereby. When the speaker and circuitry are secured, the external pre-formed faceplate to which the circuitry may be connected, will be accessible for insertion of the battery cell, programming lead or manual adjustment controls from the part of the ear-piece emergent in the wearer's concha.

It is worth mentioning that the construction can advantageously include a separate core tubing which may be fitted within the passages andlor the 14 cavity to maximise acoustic transmission, and to minimise feedback.

Although the micro-speaker and associated programmableladjustable circuitry are essential components of the device, the particular choice of microspeaker is not in itself a feature of this invention, and it may be of any available kind small enough to fit within the limited space available and yet still perform its function. Currently it is preferred to employ the type of micro-speaker usually called an E H Magnetic Receiver, e.g., that sold as a part of the E H or E C series of transducers which are commercially available from Knowles Electronics Company of Burgess Hill, West Sussex, England. Also, many types of programmable circuitry could be used for the purpose, although again they would need to be small enough to fit into the space available within the earplug itself or the aforesaid module. Currently it is preferred to employ the type of circuitry known as digitally programmable analogue assembly, e.g. that sold as part of the Astro series which is commercially available from Phonak UK Ltd., Warrington, Cheshire, England. Although for purposes of development the Astro assembly could be used, it is by no means exclusively appropriate and many other forms of assembly could be employed for the same purpose.

According to another aspect of the present invention there is also provided a kit of parts, for use in the above-described method, said kit of parts comprising.

- (i) a disposable pad for insertion within an aural cavity adjacent to and for protection of the eardrum, - (ii) the precursors of a medical-grade silicone impression material and if appropriate initiator(s) for bringing about polymerisation of the impression material to form a plug of a flexible but hard rubbery consistency; - (iii) moulding material for forming a complementary mould around the resultant hard rubbery plug aforesaid; - (iv) synthetic resin plastics material for casting within the resultant mould aforesaid, - (v) synthetic resin plastics material for manufacturing the module casing, if the modular version of the device is to be used; - (vi) a micro-speaker for positioning within a cavity within the resultant plastics earplug between an eardrum-directed passage and the programmable electronics, or within the module with the aforesaid electronics; 16 - (vii) an electronic assembly which is capable of being connected to a computer or other form of programming device for the purposes of digitally programming the circuitry so as to adjust the pitch and amplitude of the input signal, and whose adjusted output would then be passed via electrical connections to the micro-speaker., - (viii) (a) programming lead(s) or connector(s) to be used for linking the device's programmable electronics to a chosen programming device; - (ix) where necessary, and when the power for this device is not derived from the external electrical connections, a battery cell of appropriate size to provide the power to drive the assembly, - (x) for non-modular versions, a retaining cover or faceplate which will incorporate a connection port for the programming lead as mentioned in (viii) to be utilised, and where necessary a passage to be traversed by electrical connectors as described in (xi), and battery housing with terminals for a battery cell as described in (ix).

- (xi) electrical connections of sufficient length to extend from the electrical circuitry positioned within said cavity through the second 17 passage or hole in the faceplate where present, or through a hole in the module shell, for interconnection externally of the plug and the wearer's ear with circuitry providing in use the signal intended for the wearer; (xii) means andlor instructions for carrying out a hearing test on the user, such as a standard BSA test, to obtain a representation of his or her preferred or deficient audible frequency profile, so as to then adjust the amplitude of the required frequencies in the output signal of the device accordingly.

According to yet another aspect of this invention there is also provided an audio-communication device, for human wear, comprising an earplug external ly-contoured to fit snugly within a wearer's aura] cavity between concha and eardrum, and within said earplug a cavity wherein a micro-speaker and adjustable electronic assembly is located and secured, said cavity communicating with first and second passages, the first passage being so constructed and arranged as to channel the audio-output of the micro-speaker to emerge adjacent the wearer's eardrum. The second passage being emergent outside the wearer's concha and traversed by electrical conductors between the circuitry within the cavity and one or more connector(s) outside the wearer's concha for attachment to external circuitry, which in use may power the microspeaker assembly and provide the signal for the wearer. A communication port is used for the electronic adjustment of the internal assembly, or for the manual adjustments, may be accessible from the side of the earplug emergent from the wearer's concha, as may be the battery housing.

The audio-communication device may and very preferably will be manufactured by the method herein described, employing the aforesaid kit of parts.

In order that the invention may be well understood, the recommended manufacturing sequence and preferred embodiments of the earplug-device made in accordance therewith will now be described in more detail, though only by way of illustration, with reference to the accompanying drawings in which:

Figure 1 is a sequence of simplified schematic diagrams, which are not to scale and do not pretend to be realistic but illustrate the successive steps involved in the manufacture of such an aud io-com mun i cation device.

Figure 2A is a perspective view from above and one side of an earplug but omitting the micro-speaker and circuitry assembly and their electrical connections, constructed by the method of this invention from the kit of parts herein envisaged., 19 Figure 3A is a plan view from above of the same earplug as in Figure 2A, Figure 213 is a perspective view from above and one side of an alternative earplug utilising the module version of this invention, but omitting the removable micro-speaker and circuitry assembly -containing module; Figure 313 is a plan view from above of the same earplug as in Figure 213; Figure 4 is a perspective view, but on a reduced scale, which shows the earplug of Figures 2A and 3A in conjunction with the other parts of the whole assembly which go to make up the personal-intercommunication system of this invention.

Referring now to Figure 1, this shows a sequence of seventeen diagrams, indicated 1 A to 1 S, in which:

Figures 1A, 113 and 1C are all similar vertical cross-sectional views through the aural cavity of an intended wearer of the device, Figures 1 D, 1 E, 1 F and 1 G are all similar cross-sectional views on a vertical diametrical plane showing the progression from an impression moulding of the aural cavity to a cast-moulding blank for the audio communication earplug; Figures 1 H, 1 J, 1 K and 1 L are similar cross-sectional views on a vertical diametrical plane through the cast-moulding blank as it is successively (i) bored out or tooled to provide the cavity and passages therein, (ii) fitted with the micro-speaker and circuit assembly within that cavity, and optional faceplate, (iii) refilled with casting resin to secure the electronics in place, and (iv) finished to yield the desired audio-commuhication device; Figures 1 M, 1 N and 1 P show similar cross-sectional views on a vertical diametrical plane through an alternative cast-moulding blank intended for use with the modular version of the device, as it is successively (i) tooled to provide the cavity and passages therein, and (ii) fitted with the electronic module assembly within that cavity; Figures 1 Q, 1 R and 1 S show cross-sectional views on a vertical diametrical plane of the manufacture of the module as its casing is successively i) moulded in the chosen moulding resin be it a soft silicone or hard acrylic from a pre-formed cast of predetermined dimensions, ii) having the insertion and positioning of the micro-speaker and electronic assembly within it, iii) attaching the required electronic connections for signal and power delivery, and 21 for connection to external circuitry for programmingladjustments, and if necessary, electrical connections to an alternative power supply of a battery cell.

The sequence of operations should be self-evident from the successive diagrams 1 A - 1 L, but will now be briefly described as follows:

Figure 1A shows the intended wearer's head, generally indicated 1, with an aural cavity 2 between the wearer's concha 3 and his eardrum 4.

In step A/B a circular pad 5 cut from a sheet of soft, flexible polyurethane foam is inserted into the aural cavity 2, adjacent the eardrum 4, as shown in Figure 1 B. Then in step BIC, the aural cavity 2 outside the eardrum-protective pad 5 is filled with a soft plug 6 of a polymerisable impression material, polymerisation of which is initiated and continued until it is cured to a hard, rubbery consistency.

The plug 6, now hard and rubbery, as well as the pad 5 are, as shown in Figure 1 D, then removed from the aural cavity 2 in step CID, and the pad 5 is discarded. The hard, rubbery plug 6 is then in step DIE thinly coated with wax 22 and embedded in an appropriate moulding material e.g. silicone or Plaster of Paris matrix 7.

After the matrix 7 has set, the plug 6 is removed therefrom in step E1F, leaving a complementary mould 8 as shown in Figure 1 F - which in the following step F/G is filled (or in fact slightly overfilled) with a silicone casting resin 9, as shown in Figure I G. This is allowed to polymerise until set 1t may be preferred that before set, mould-cores or tools (not shown) of correct dimensions are inserted into the cast giving the correct cavities and passages without the need for material to be bored out or removed by other means at a later stage. The surplus overfil is trimmed off, down to the horizontal surface indicated at 10. One now has achieved an earplug with the desired external topography, which will fit snugly within the wearer's aural cavity and very largely exclude background noise, however intrusive.

It remains however to fit this plug with the necessary equipment for delivery of the desired audio-signal to the wearer's eardrum, whether it be permanently secured or inserted in a removable modular form. At this point, the plug 11 is removed from the mould 8 and in step G/H as shown inFigure 1 H, if the necessary cavity or passages have not already been formed by the use of various forming tools or mould-cores, the plug 11 is bored out to provide a main cavity 12 by means of reamer 13. A first passage 14 and a second passage 16, 23 both communicating with the cavity 12, are bored out by means of drills 15. if required, a further ventilation passage (not shown) may also be bored out.

Then in step HIJ a micro-speaker 17 is electrically connected to associated programmable electronic assembly 18 and both are positioned within cavity 12. Electrical connections may be made between assembly 18 and an optional retaining faceplate 19 which may have housing for a battery and reprogramming port (not shown), if needed.

In order to secure the micro-speaker 17 and electrical assembly 18 within the cavity 12, in step J/K the unoccupied residue of the latter is refilled with a casting resin 9, which could conveniently be the same silicone as used in step FIG to form the blank plug 11, as shown in Figure 1 K. After curing, the refi lied casting resin 9 surrounds and overlays the micro-speaker 17 and electrical assembly 18, holding it in position with the speaker 17 directed down passage 14 towards the intended user's eardrum, and with the electrical conductors 20, which may power the speaker and electrical assembly and deliver the signal to it, traversing the second passage 16 and emerging from it as schematically shown in Figure 1 K. If the second passage 16 is not utilised, the conductors 20 may traverse an alternative passage or hole in the faceplate 19, for subsequent connection to the rest of the audio- communication system.

24 Then finally in step KIL the surplus "overfill" of casting resin is trimmed off, using e.g., a scalpel or grinding disc, to leave a level external surface 21 and this forms the finished product of this invention as shown in Figure 1 L.

Alternatively, if the modular form of the device is to be used, the blank earplug 11 of Figure 1 G may be prepared accordingly by proceeding with step G/M instead of step GIH. As is shown in Figure 1 M, before the blank earplug 11 is fully set, a mould-core or tool 22 of equivalent size and shape to that of the module to be used, is inserted into the casting resin 9 so as to form a cavity 24 shaped so as to receive the removable module. Passage 14 may be formed by a mould-core or tool, or by a drill 15 as in the non-modular version.

The module cavity 24, as shown in Figure 1 N, is suitably shaped so that the module 25 may be snapped into place so as to fit snugly within the plug, as shown in figure 1 P, but being removable by the application of a slight force.

The preparation of the removable module 25 is shown in the sequence of Figures 10 to 1 S. The pre-formed cast 26 is filled with the desired resin so as to form the hollow module shell 27. Then as shown in step QIR, the microspeaker 17 and electronic assembly 18 are inserted into the shell 27 and fixed in place by gluing or other fixing means. The components are then connected via electrical connections 20, as shown.in figure 1 S. The remaining space 28 in the module may be either filled with an appropriate material, or left empty.

The product thus made is shown in a more life-like manner in Figures 2A, 2B, 3A, 313 and 4, where it can be seen that the finished plug 11 contains a cavity 12124 which accommodates the micro-speaker 17 and programmable circuit assembly 18, or module 25 containing both, said cavity 12 having been subsequently re-filled with casting resin 9 (as shown in Figure 4) so as to secure the assembly in situ therein, with its speaker 17 directed down the primary passage 14 and its electrical conductors 20 emergent via the secondary passage 16.

Figures 2A, 3A and 4 show a further embodiment of the invention which also includes an optional upstanding peg 29 on the external surface which extends from the user's concha, said peg being used to facilitate removal of the plug from the ear.

As can also be seen from Figure 4, there are separate electrical conductors 20 leading out from the two earplug programmable speakerandcircuitry assemblies 17118, one for each of the wearer's ears. These separate conductors 20 both lead to a common conventional phono-plug 30, by means of which the entire assembly can be plugged into the external electrical circuitry (not shown) of e.g. an inboard crewintercommunication system or an external 26 radio-communication link, from which both the power needed to operate the micro-assembly and the signals intended for the wearer can be derived.

27

Claims (1)

1. A programmable or adjustable audio-communication device, for human wear, comprising an earplug externally contoured to fit snugly with a wearer's aural cavity between concha and eardrum, and within said earplug a cavity wherein a micro-speaker and digitally programmable or adjustable circuitry assembly, electrically connected to said micro-speaker are located, said cavity communicating with at least one passage, said primary passage being constructed and arranged so as to channel the audio- output of the microspeaker to emerge adjacent the wearer's eardrum, and optionally a secondary passage or other access means, traversed by electrical conductors between the internal micro-speaker and circuit assembly and one or more connector(s) outside the wearer's concha for attachment to external circuitry which in use provides the signal for the wearer.

2. A device as claimed in claim 1, and substantially as herein described.

3. An audio-communication device, for human wear, substantially as herein described with reference to andlor as shown in figures 2A, 2B, 3A, 3B and 4 of the accompanying drawings.

4. A method for construction of a personalised programmable or adjustable ear-speaker assembly being part of the audio-communication device claimed in any of the preceding claims, which is adapted to fit snugly within the intending signal-receiver's aural cavity and thereby exclude nearly all extraneous 28 background noise, which however will deliver the desired digitally, electronically or manually adjusted signal to the signal-receiver's eardrum, said method comprising the steps of:

(a) filling at least the outermost parts of the signal-receiver's aura] cavity with a medical-grade polymerisable impression material, and initiating and continuing polymerisation thereof until it has set to a stillflexible but hard rubbery consistency earplug, (b) removing the flexible, rubbery earplug thus formed from the intending signal receiver's aura] cavity and using it as a mould-former in creating a complementary mould in a moulding material, (c) removing the mould-former from the resultant mould, and then casting synthetic resin plastics material, non-irritant for human epidermal and epithelia[ tissue, within said complementary mould, with or without mould-cores adapted for form a cavity andlor passages within the resultant moulding; (d) separating the resultant cast earplug from said complementary mould, removing any mould-cores from andlor boring out the cast earplug so as to form the first and second passages therein, said first passage extending within the earplug from that part thereof which in use will be located adjacent to the wearer's eardrum, and said second passage extending from the part thereof which emerges from the wearers concha, said first and second passages both communicating 29 with a cavity within the earplug; (e) locating a micro-speaker and its electrical connections with programmable electronic circuitry and the said circuitry, within said cavity with the speaker thereof directed along the passage towards the wearer's eardrum; (f) testing the hearing of the intended user, so as to obtain a representation of the user's hearing levels or preferences across the audible frequency spectrum., and (g) programming or adjusting the electronic circuitry of step (e) so as to compensate for any hearing deficiency or preferences detected in the. test of step (f).

5. A method as claimed in claim 4, which also includes the preliminary step of inserting a disposable pad within the aural cavity adjacent to and able to protect the eardrum before carrying out step (a), as well as the subsequent additional step, following removal of the earplug in step (b) of removing said pad from the aural cavity. 6. A method as claimed in claim 4, in which the disposable pad is formed of a soft and flexible grade of open-pore polyurethane foam7. A method as claimed in any of claims 4 to 6, in which the polymerisable impression material employed in step (a) is a medical-grade silicone impression resin.

8. A method. as claimed in any of claims 4 to 7, in which the moulding material employed in step (b) to form the complementary mould is a silicone resin or Plaster of Paris.

9. A method as claimed in any of claims 4 to 8, in which the casting resin used in step (c) to cast the earplug-blank is a hard acrylic resin, and additionmix silicone resin or a UV-curing resin.

10. A method as claimed in any of claims 4 to 9, in which the cavity and any required passages are all created in step (d), by boring out the earplug-blank with one or more drili(s) andlor reamer(s).

11. A method as claimed in any of claims 4 to 9, in which the cavity and any required passages are created in step (c) by the placement of tools within the earplug-blank.

12. A method as claimed in either of claims 10 or 11, in which the earplugblank is bored out so that within the cavity and at or adjacent the intersection of the first passage with said cavity there is provided a seating which serves to locate and support the micro-speaker within the cavity.

13. A method as claimed in any of claims 4 to 11, in which the microspeaker and its associated circuitry are formed into a removable module which can easily be inserted into and removed from a corresponding cavity in the earplug.

14. A method as claimed in any of claims 4 to 13, in which a feedback free seal is provided between the face of the micro-speaker assembly or module and the walls of the cavity adjacent and around the intersection of the first 31 passage with said cavity.

15. A method as claimed in any of claims 4 to 14, in which the microspeaker and associated circuitry are powered by an internal battery cell within the earplug or module.

16. A method as claimed in any of claims 4 to 14, in which the microspeaker and associated circuitry are powered by external connection to the source of the communication signal.

17. A method as claimed in any of claims 4 to 16, in which the circuitry is programmed or adjusted so as to compensate for the user's hearing deficiencies andlor preferences, by adjusting the amplitude of the appropriate frequencies.

18. A method as claimed in any of claims 4 to 17, and substantially as herein described.

19. A method for construction of an ear-speaker assembly, substantially as herein described with reference to Figure 1 of the accompanying drawings.

20. A kit of parts for use in the method claimed in any of claims 4 to 19 which comprises..

(i) a disposable pad for insertion within an aural cavity adjacent to and for protection of the eardrum; (ii) the precursor(s) of a medical-grade polymerisable impression material, and if appropriate initiator(s) for polymerisation thereof, to form a cured plug contoured to fit snugly within an aural cavity; 32 (iii) moulding material for forming a complementary mould around the cured plug aforesaid; (iv) synthetic resin plastics material for casting within the complementary mould aforesaid to form an earplug-blank, andlor a module casing; (v) a micro-speaker, for positioning within a cavity formed in the earplug-blank or within a module to be positioned within a cavity of complimentary dimensions formed in the earplug blank aforesaid, which cavity communicates with an eardrum-directed primary passage; (vi) an electronic assembly, which is capable of being connected to a computer or other form of programming device for the purposes of digitally programming the circuitry so as to adjust the pitch and amplitude of the input signal, and whose adjusted output would then be passed via electrical connections to the micro-speaker; (vii) (a) programming lead(s) or connector(s) to be used for linking the device's programmable electronics to a chosen programming device, (viii) where necessary, a battery cell of appropriate size to provide power to drive the assembly, (ix) for non-modular versions, an optional retaining cover or faceplate which may incorporate a connection port for the programming lead to be utilised, and where necessary a passage to be traversed by electrical connectors, and battery housing with terminals for a battery cell., 33 (x) electrical connections of sufficient length to extend from the electrical circuitry positioned within said cavity through the secondary passageorholein for interconnection externally of the plug and the wearer's ear with circuitry providing in use the signal intended for the wearer, (xi) means andlor instructions for carrying out a hearing test on the user, to obtain a representation of his or her preferred or deficient audible frequency profile, so as to then adjust the amplitude of the required frequencies in the output signal of the device accordingly.

21. A kit of parts as claimed in claim 20 and substantially as herein described with reference to andlor as shown in any of the accompanying drawings.

22. A programmable or adjustable earplug constructed according to a method as claimed in any of claims 4 to 19.

23. A programmable or adjustable earplug constructed from a kit of parts as claimed in either of claims 20 or 21.