# US 10,375,467 B2 · Systems, apparatus, and methods for hearing protection

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- Number: US 10,375,467 B2
- Document ID: US10375467B2
- Status: Granted
- Kind: B2
- Application number: 15/870,372
- Filed: 2018-01-12
- Published: 2018-06-07
- Granted: 2019-08-06
- Earliest claimed: 2015-07-14
- Assignees: Massachusetts Institute of Technology
- Applicants: Massachusetts Institute of Technology
- Inventors: Jun Xu; Nicholas Fang
- Web page: https://patentgrep.com/patent/US10375467B2

## CPC

- H04R 1/1083: {Reduction of ambient noise (active noise reduction per se G10K11/175; protective devices for the ear, e.g. providing acoustic protection A61F11/06)}
- A61F 11/08: internal, e.g. earplugs
- G10K 11/162: Selection of materials
- H04R 1/1016: {Earpieces of the intra-aural type}
- H04R 3/04: for correcting frequency response
- A61F 11/085: {including an inner channel}
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)
- G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR

## Abstract

Systems, apparatus, and methods for filtering acoustic energy include a first conduit substantially aligned with a longitudinal axis and defining a first opening for receiving incident acoustic energy from the environment. A cavity in fluid communication with the first conduit selectively amplifies and/or dampens the acoustic energy based on an associated resonance frequency. A moving element disposed in the cavity may be displaced relative to the cavity in a direction substantially aligned with the longitudinal axis and in an amount related to a sound pressure level of acoustic energy in the cavity. A second conduit substantially aligned with the longitudinal axis and in fluid communication with the cavity selectively attenuates acoustic energy from the cavity based on the sound pressure level by receiving at least some of the acoustic energy from the cavity and/or the moving element when it is displaced from the cavity.

## Claims

### Claim 1

A hearing protection device having an outer shape and size for inserting at least a portion of the device in a human ear canal, the outer shape defining a first opening for receiving incident acoustic energy from an environment and a second opening positioned opposite to the first opening for transmitting filtered acoustic energy into the ear canal, the device having a longitudinal axis extending from the first opening to the second opening, the device further defining:
a first conduit extending inward from the first opening;
a cavity in fluid communication with the first conduit, the cavity for selectively amplifying and/or dampening the acoustic energy based on a resonance frequency of the cavity, the cavity further comprising:
a mesh element disposed in a plane substantially normal to the longitudinal axis, the mesh element dividing the cavity into a proximal compartment for receiving the acoustic energy from the first conduit and a distal compartment; and
liquid disposed in the distal compartment, wherein no significant amount of the liquid is present in the proximal compartment, the liquid displaceable relative to the device in a direction substantially aligned with the longitudinal axis; and
a second conduit in fluid communication with the distal compartment and extending outward to the second opening, the second conduit being tapered towards the second opening and for receiving a portion of the displaced liquid in response to a sound pressure level of the acoustic energy, an extent of displacement of the liquid into the second conduit based on the sound pressure level of the acoustic energy, wherein the second conduit selectively attenuates acoustic energy from the cavity based on the extent of displacement of the liquid into the second conduit.

### Claim 2 (depends on 1)

The hearing protection device of claim 1, wherein the device is configured to be combined with an ear plug.

### Claim 3 (depends on 1)

The hearing protection device of claim 1, wherein the outer shape comprises at least one of a domed flange, a bell-shape, and a bullet-shape.

### Claim 4 (depends on 1)

The hearing protection device of claim 1, wherein the device comprises at least one of a foam, a silicone, and a thermoplastic.

### Claim 5 (depends on 1)

The hearing protection device of claim 1, wherein the device is manufactured using at least one of additive manufacturing, rotational plastic molding, injection molding, blow molding, extrusion molding, and thermoforming.

### Claim 6 (depends on 1)

The hearing protection device of claim 1, wherein the device has an outer radius from about 5 mm to about 7 mm and an outer length from about 10 mm to about 14 mm.

### Claim 7 (depends on 1)

The hearing protection device of claim 1, wherein the mesh element comprises at least one of a foam and a metal.

### Claim 8 (depends on 1)

The hearing protection device of claim 1, wherein the mesh element has a thickness from about 0.2 mm to about 0.5 mm.

### Claim 9 (depends on 1)

The hearing protection device of claim 1, wherein the mesh element has a pore size from about 0.1 mm to about 0.2 mm.

### Claim 10 (depends on 1)

The hearing protection device of claim 1, wherein a mesh element maintains the liquid at a particular position in the cavity.

### Claim 11 (depends on 1)

The hearing protection device of claim 1, wherein the position of the liquid is based at least in part on at least one of:
an acoustic pressure field difference between the cavity and the second conduit; and
a surface tension between the liquid and at least one of the mesh element, air, an inner surface of the cavity, and an inner surface of the second conduit.

### Claim 12 (depends on 11)

The hearing protection device of claim 11, wherein at least one of the mesh element, the inner surface of the cavity, and the inner surface of the second conduit is treated to control the surface tension.

### Claim 13 (depends on 11)

The hearing protection device of claim 11, wherein at least one of a shape, an angle, and a texture of the inner surface of the second conduit is selected to modify the acoustic pressure field difference between the cavity and the second conduit.

### Claim 14 (depends on 1)

The hearing protection device of claim 1, wherein a length of the second conduit is selected to modify frequencies transmitted of the filtered acoustic energy.

### Claim 15 (depends on 14)

The hearing protection device of claim 14, wherein the length of the second conduit is selected to allow transmission of frequencies from about 50 Hz to about 4,000 Hz.

### Claim 16 (depends on 14)

The hearing protection device of claim 14, wherein the length of the second conduit is selected to allow transmission of frequencies from about 100 Hz to about 800 Hz.

### Claim 17 (depends on 1)

The hearing protection device of claim 1, wherein the mesh element and the liquid form a liquid membrane.

### Claim 18 (depends on 1)

The hearing protection device of claim 1, wherein the liquid forms a meniscus in each of a plurality of pores of the mesh element for a plurality of menisci.

### Claim 19 (depends on 1)

The hearing protection device of claim 1, wherein the mesh element comprises a cascade of mesh elements disposed in a plurality of parallel planes, each plane of the plurality of planes being substantially normal to the longitudinal axis, the cascade of mesh elements dividing the cavity into more than two compartments.

### Claim 20 (depends on 19)

The hearing protection device of claim 19, wherein liquid is disposed in at least one intermediate compartment between a first mesh element and a second mesh element of the cascade of mesh elements such that the liquid forms a meniscus in each of a plurality of pores of the first mesh element and each of a plurality of pores of the second mesh element.

### Claim 21

A method for protecting hearing of a listener in an environment, the method comprising:
inserting at least a portion of a device in a human ear canal, the device having an outer shape defining a first opening for receiving incident acoustic energy from the environment and a second opening positioned opposite to the first opening for transmitting filtered acoustic energy into the ear canal, the device having a longitudinal axis extending from the first opening to the second opening;
receiving incident acoustic energy from the environment via the first opening in the device, a first conduit extending inward from the first opening;
selectively amplifying and/or dampening the acoustic energy via a cavity in fluid communication with the first conduit based on a resonance frequency of the cavity, the cavity further comprising a mesh element disposed in a plane substantially normal to the longitudinal axis, the mesh element dividing the cavity into a proximal compartment for receiving the acoustic energy from the first conduit and a distal compartment;
selectively attenuating, based on a sound pressure level of acoustic energy in the cavity, acoustic energy from the cavity via liquid disposed in the distal compartment and a second conduit in fluid communication with the distal compartment and extending outward to the second opening, the liquid displaceable relative to the device in a direction substantially aligned with the longitudinal axis, the second conduit being tapered towards the second opening and receiving a portion of the displaced liquid in response to a sound pressure level of the acoustic energy, an extent of displacement of the liquid into the second conduit based on the sound pressure level of the acoustic energy, wherein no significant amount of the liquid is present in the proximal compartment, and wherein the second conduit selectively attenuates the acoustic energy based on the extend of displacement of the liquid into the second conduit; and
transmitting the filtered acoustic energy via the second opening of the second conduit positioned opposite to the first opening along the longitudinal axis.

### Claim 22

An apparatus for filtering acoustic energy in an environment, the apparatus comprising:
a first conduit substantially aligned with a longitudinal axis, the first conduit defining a first opening for receiving incident acoustic energy from the environment;
a cavity in fluid communication with the first conduit, the cavity for selectively amplifying and/or dampening the acoustic energy based on a resonance frequency of the cavity, the cavity comprising a moving element disposed in a distal compartment of the cavity and not being present in a proximal compartment of the cavity, the moving element displaceable relative to the apparatus in a direction substantially aligned with the longitudinal axis; and
a second conduit substantially aligned with the longitudinal axis and in fluid communication with the cavity, the second conduit being tapered towards a second opening and for receiving a portion of the displaced moving element in response to a sound pressure level of the acoustic energy, an extent of displacement of the moving element into the second conduit based on the sound pressure level of the acoustic energy, the second conduit further for selectively attenuating acoustic energy from the cavity based on the extent of displacement of the moving element into the second conduit, the second opening positioned opposite to the first opening along the longitudinal axis for transmitting filtered acoustic energy.

### Claim 23

A method for filtering acoustic energy in an environment, the method comprising:
receiving incident acoustic energy from the environment via the first opening of a first conduit substantially aligned with a longitudinal axis;
selectively amplifying and/or dampening the acoustic energy via a cavity in fluid communication with the first conduit based on a resonance frequency of the cavity, the cavity comprising a moving element disposed in a distal compartment of the cavity and not being present in a proximal compartment of the cavity, the moving element displaceable in a direction substantially aligned with the longitudinal axis;
selectively attenuating acoustic energy from the cavity via a second conduit substantially aligned with the longitudinal axis and in fluid communication with the cavity, the second conduit being tapered towards a second opening and for receiving a portion of the displaced moving element in response to a sound pressure level of the acoustic energy, an extent of displacement of the moving element into the second conduit based on the sound pressure level of the acoustic energy, wherein the second conduit selectively attenuates the acoustic energy based on the extend of displacement of the liquid into the second conduit; and
transmitting filtered acoustic energy via a second opening defined by the second conduit and positioned opposite to the first opening along the longitudinal axis.