WO2001026421A1

WO2001026421A1 - Disposable hearing aid tip designs

Info

Publication number: WO2001026421A1
Application number: PCT/US2000/027842
Authority: WO
Inventors: Marvin A. Leedom
Original assignee: Sarnoff Corporation
Priority date: 1999-10-06
Filing date: 2000-10-06
Publication date: 2001-04-12

Abstract

The present invention relates to a disposable hearing aid having a hard shell (92) and a compliant tip (94). The shell includes a battery, electronics, a microphone and a receiver. The compliant (94) tip attaches to the shell by a flexible core (96). The compliant tip (94) can be formed of layers of fingers (98) or protrusions. The compliant tip (94) can also be formed of a fluid filled bladder.

Description

DISPOSABLE HEARING AID TIP DESIGNS

BACKGROUND OF THE INVENTION

Hearing aids are delicate electro-acoustical devices that are intended to perform flawlessly in the harsh environment of the human ear. Hearing aid manufacturers use hard durable earmold materials to protect the delicate electronics and transducers from adverse conditions in and out of the ear. Such durable materials are intended to survive a greater than four year usage life. The earmold can be used not only to protect the internal components of the hearing aid, but also to form an interface between the electronics and the ear canal. This interface must be created to prevent acoustical feedback, to retain the electronics in the ear and prevent irritation or fatigue of the ear canal. A design conflict for the earmold can then exist between the need to have a soft, pliant, nonirritating and comfortable material, and the need to have a durable material to protect the internal electronic components which can last more than four years. A disposable hearing aid is one designed to have a useful life of much less than the traditional four years. The useful life of a disposable hearing aid can also be governed by the life of the battery. If the battery can be replaced, the hearing aid is no longer disposable and the advantages of the disposable aid are lost. However, a number of other variants on the disposable aid are possible. These variants look to maintain the advantages of disposability while making the system more convenient, comfortable, longer lasting or providing better performance.

"One-size-fits-all" type hearing aids generally lack a flexibility of their tips. Such a lack of flexibility prevents deep penetration into the bony region of an ear canal by the hearing aid. Such hearing aids are also unable to create an acoustic seal in the ear canal. Without such penetration or such a seal in the bony region, the hearing aid can create an occlusion effect in the wearer. Also, hearing aids lacking a proper acoustic seal are prone to feedback.

Feedback is a nagging, unsolved problem for hearing aid manufacturers and dispensers. Feedback in a hearing is present in several forms: electrical, acoustical and mechanical. While electrical feedback is more easily controllable with additional circuitry, the latter two forms of feedback in hearing aids remain significant problems that often reduce the effectiveness of hearing aid fittings. Acoustical or mechanical feedback signals from the hearing aid receiver may be transduced by the hearing aid microphone, amplified in the circuitry and output from the receiver again but with higher gain, creating a feedback loop, and potentially oscillation. A criteria by Nyquist states that a system will oscillate if the gain of the open loop transfer function at a particular frequency is greater than unity and its phase shift of the open loop transfer function is a multiple of 360 degrees. Acoustical feedback occurs through the air inside of the hearing aid housing as well as on the outside of the hearing aid while it is being worn. Mechanical feedback occurs because of the receiver vibrating the hearing aid housing. Hearing aid designers have used many techniques to prevent the creation of such feedback loops. Included are rubber isolation mounts for the microphone and receiver, stiff tubes on the receiver output port and electronically filtering the hearing aid output to suppress energy at the most likely to be troublesome feedback frequencies. Unfortunately, hearing aids frequently have feedback oscillation frequencies in the very range at which the wearer requires amplification most, such as in the frequency range between 1500 and 5000 Hz.

SUMMARY OF THE INVENTION

One possible solution to the conflict between comfort and durability of the earmold is the creation of a disposable hearing aid which uses ultra soft earmold materials that may not last over a four year period, but can be mass produced in an economically competitive manner. The earmold can therefore be replaced more frequently than the disposable hearing aid. An earmold that is replaced on a more frequent basis than the replacement cycle of the disposable aid can provide a user with benefits. If the earmold is replaced on a daily basis, as compared to a base unit which is replaced after a much longer period of time than the earmold, the user can be provided with a high degree of comfort, cleanliness, and performance. Earmold tip flexibility is necessary to allow for deep ear canal insertion of a hearing aid to overcome the convolutions present in a typical ear canal. An earmold having a flexible tip incorporated with the earmold can have several advantages. These advantages include potentially deep ear canal fittings, efficient coupling of the sound emitted from the receiver to the ear drum, and a corresponding reduction in the required output levels of the receiver. The flexible tip can also provide a comfortable fit even for cases where the tip is located in the bony region of the ear canal. It is observed that when the tip creates a seal in this bony region, the occlusion effect is substantially mitigated.

The compliance of an earmold tip of a hearing aid is also important in hearing aid design. If the earmold tip is compliant enough, the tip can fit into many different sizes and shapes of ear canals. A desirable tip is one that slides easily into the bony structure of the ear canal, feels comfortable and provides a good acoustic seal.

A disposable hearing aid can include a hearing aid portion, a flexible core and a compliant tip portion. The hearing aid portion includes a shell containing a battery, a receiver, a microphone and electronics. The flexible core attaches to the hearing aid portion and forms a sound bore to allow sound produced by the hearing aid portion to travel to the ear canal. The compliant tip portion is adapted to be inserted into an ear canal, surrounds the flexible core and forms an acoustic seal in the ear canal. The tip material can include layers of fingers surrounding the flexible core. The layers of fingers can be made from an elastomer material. The tip material can also include a fluid-filled bladder surrounding the flexible core. The fluid- filled bladder can have air within the bladder or can have liquid within the bladder. The fluid-filled bladder can also have a flexible bladder wall to allow for flexibility of the fluid-filled bladder to accommodate size changes within the ear canal.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.

Figures 1-4 illustrate a disposable hearing aid having a compliant tip.

DETAILED DESCRIPTION OF THE INVENTION Figures 1-4 illustrate a disposable hearing aid having a compliant tip 90. The disposable hearing aid with a compliant tip 90 includes a hearing aid 92 having a hard shell, which contains the battery and all of the electronics including a receiver and a microphone, and a compliant tip 94 that can penetrate deep into an ear canal and is attached to the hearing aid 92 by a flexible core 96. The flexible core forms a sound bore which allows sound produced by the hearing aid to travel into the ear canal.

The compliant tip 94 can consist of many layers of thousands of tiny fingers 98 arranged around a flexible core 96, as shown in Figures 1 and 2. The fingers 98 can be made from a soft elastomer such as silicone rubber, for example. The fingers 98 can also be formed into a round or rectangular cross section, shown in Figure 2. When the fingers 98 of the tip 94 slide into an irregular shaped ear canal, the fingers 98 can bend, twist, or interleave to form an acoustic seal to separate an inner and outer area of the ear canal. The flexible core 96 at the center of the fingers 98 of the tip 94 is hollow, thereby forming a sound bore 100. The sound bore 100 allows amplified sound to pass through the tip 94 to the inner ear. The flexible core 96 can accommodate any angle change in the ear canal while the fingers 98 can accommodate any size or shape change in the ear canal.

The compliant tip 94 can also consist of a fluid filled bladder 102 around the flexible center core, as shown in Figures 3 and 4. The bladder can have a donut-like shape. The fluid within the bladder 102 can be air or liquid, for example. If the bladder 102 is filled with air, when the tip 94 is placed within an ear canal and the tip 94 is deformed, the air can compress and force the thin bladder walls 104 to stretch to accommodate various ear canal shapes and sizes. If the bladder 102 is filled with a liquid, such as water, the water will flow to accommodate shape changes of the canal. However, when liquid is used to fill the bladder 102, the walls changes. The liquid can contain a jelling agent to prevent any feeling of liquid sloshing in the user. The fluid filled bladder 102 can fill a void smoothly, rather than buckle like solid rubber rings when the rings enter a cavity which is much smaller than the diameter of the ring. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.

Claims

CLAIMS What is claimed is:

1. A disposable hearing aid comprising: a hearing aid portion wherein the hearing aid portion comprises a shell containing a battery, a receiver, a microphone and electronics; a flexible core attached to the hearing aid portion, the flexible core forming a sound bore, thereby allowing sound produced by the hearing aid portion to travel to the ear canal; and a compliant tip portion adapted to be inserted into an ear canal, wherein the tip portion smrounds the flexible core and wherein the tip portion forms an acoustic seal in the ear canal.

2. The disposable hearing aid of Claim 1 wherein the tip material comprises layers of fingers surrounding the flexible core.

3. The disposable hearing aid of Claim 2 wherein the layers of fingers comprise an elastomer material.

4. The disposable hearing aid of Claim 1 wherein the tip material comprises a fluid-filled bladder surrounding the flexible core.

5. The disposable hearing aid of Claim 4 wherein the fluid-filled bladder comprises air within the bladder.

6. The disposable hearing aid of Claim 4 wherein the fluid-filled bladder comprises liquid within the bladder.

7. The disposable hearing aid of Claim 4 wherein the fluid-filled bladder further comprises a flexible bladder wall to allow for flexibility of the fluid-filled bladder to accommodate size changes within the ear canal.