JPH11308685A - Active noise-reduction headset - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved active noise-reduction headset. SOLUTION: A module which is suitable for the use of an active noise reduction headset includes an enclosure and having a wall to separate the inside of the enclosure from the outside of the enclosure. A driver 18 having a diaphragm 21 is mounted to part of the wall. The driver 18 emits a sound wave to cancel noise therearound. A port that is resonated connects the inside and the outside. A resonance damper attenuates the resonance of the port.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to active noise reduction.

[0002]

BACKGROUND OF THE INVENTION As a technical background, U.S. Pat.
Nos. 4,581, 4,922,542 and 5,3
No. 05,387 is incorporated.

[0003]

An important object of the present invention is to provide an improved active noise reduction headset.

[0004]

In accordance with the present invention, a module suitable for use in an active noise reduction headset includes an enclosure having a wall. A driver is attached to a part of the wall. Ports interconnect the interior and exterior of the enclosure.
A damper is coupled to the port.

In another aspect of the invention, an active noise reduction headset includes an earcup surrounding first and second cavities separated by a split. The headset also includes a more comfortable sealing pad.
A driver with a diaphragm is mounted in the split and emits sound waves into the first cavity, which attenuates ambient noise. The port interconnects the exterior of the second cavity and the enclosure.

[0006] Other features, objects, and advantages will be apparent from the following detailed description, which refers to the accompanying drawings.

[0007]

DETAILED DESCRIPTION OF THE INVENTION Referring now to the drawings, and more particularly to FIG. 1, there is shown an active noise reduction headset according to the present invention. Headband 5
6 are attached to the two earcup structures 58. Each of the earcup structures 58 includes an earcup portion 5
0 and a comfort pad 54. The headband can be one of many types, including a headband in which the length of the headband or the position of the earcup structure on the headband is adjustable. The connection between the headband 56 and the earcup structure allows for one or more axial adjustments to the headband. In use, the headband 56 holds the earcup structure 58 over the user's ear and either surrounds the ear (circumaural) or covers the ear (supraural).

Referring to FIGS. 2-4, schematic cross-sectional views of an earcup structure 58 are shown. In FIG. 2, an earcup shell 50 surrounds a front cavity 52. As the comfort pads 54 adhere to the side of the user's head, they seal the user's ears from most of the ambient noise. The front cavity 52 includes the active noise reduction module 1.
Surround 0. The active noise reduction module 10 includes a driver 18 with a sound radiation diaphragm 21.
A port 16 and an acoustic resistance opening 17 pass through the earcup shell 50 in parallel. These are described in more detail below. 3 and 4, a passage 19 connects the port and the resistive opening 17 to the surrounding environment. The dimensions of the passage 19 are such that this passage does not act as a port nor as a waveguide for the sound waves emitted by the diaphragm 21. The acoustics are the same as if both port 16 and resistive aperture 17 were connected directly to the surrounding environment as in FIG. A damping material 53 (eg, an open cell foam) may be disposed within the front cavity 52 to reduce resonance in the front cavity and assist in passive damping. Embodiments such as in FIGS. 3 and 4 allow for a flexible arrangement of the active noise reduction module, minimizing modifications to the earcups, and providing the active noise reduction module with a variety of different earcups. There is an advantage that 10 can be implemented.

In operation, microphone 22 measures sound pressure. A circuit (not shown) is connected to the microphone 22
Is compared with the sound pressure of sound waves emitted by the diaphragm 21 to detect ambient noise and transmit a signal to the driver 18, which is similar to ambient noise but out of phase with ambient noise The ambient noise is greatly attenuated by radiating the acoustic pattern to the diaphragm 21.

Referring to FIGS. 5A-5B, an active noise reduction module 10 is illustrated. An enclosure 12 surrounds the rear cavity 14 (FIGS. 6A-6D). Port 16 and acoustic resistance aperture 17
Penetrates the wall of the enclosure 12. A driver 18 is mounted on the surface of the enclosure 12. A microphone 22 is attached to an outer surface of the enclosure 12. In the present embodiment, the microphone 22 is attached to a position near the end of the diaphragm 21, and the pickup surface faces radially inward. That is, it is attached so that a straight line perpendicular to the pickup surface is substantially perpendicular to the axis 24 of the driver 18.

In one embodiment of the invention, the enclosure 12 is generally cylindrical and the driver 18 is approximately 42 mm in diameter and is mounted in one of the planes of the cylinder. The rear cavity 14 surrounded by the enclosure 12 typically has a volume of about 10 to 20 cubic centimeters, and the front cavity 52 typically has a volume of about 100 to 200 cubic centimeters. The acoustic mass of the port 16 and the compliance of the rear cavity 14 are typically tuned to a frequency of about 300 Hz. Acoustic resistance opening 16 provides an acoustic resistance of about 1x16 ⁷ ohm. The resistance opening 17 may be an opening 17a having an acoustic resistance coating 17b, or may be an opening filled with an acoustic resistance material.

Referring now to FIGS. 6A-6D, an active noise reduction module 10 is shown.
In these figures, certain elements have been omitted or changed in order to better explain the invention. B to FIG. 6 of FIG.
Some effects of the features of the embodiment of FIG. 6A are described below using D. In FIG. 6B, the port 16 and the resistance opening 17 are omitted. In FIG. 6C, the resistance opening 17 is omitted. In FIG. 6D, the resistance opening 17 is omitted and the acoustic resistance material 16a is
6 is inserted. (Alternatively, the opening of port 16 may be coated with an acoustically resistive material).

In the embodiment of FIG. 6D, the acoustic resistance of the acoustic material 16 a connects the rear cavity 14 in communication with the surrounding environment in series with the mass of air in the port 16. In the embodiment of FIG. 6A, the acoustic resistance of the resistive aperture 18 connects the rear cavity 14 to the surrounding environment in parallel with the mass of air in the port 16.

Referring now to FIG. 7, there is shown a graph of a computer simulation in which the response of the driver 18 was performed as a function of frequency, and the effects of various elements of the embodiment of FIG. Represents Curve 24
Represents the response of the driver 18 in the embodiment of FIG. 6B. Curve 26 represents the response of driver 18 in the embodiment shown in FIG. 6C. Compared to curve 24, curve 26 not only shows a better response at lower frequencies, but in this case at a port resonance frequency of 300 Hz,
Has low output. Curve 28 represents the response of driver 18 in the embodiment shown in FIG. Compared to curve 26, curve 28 shows a smoother frequency response and an improved response at lower frequencies. Curve 30
Represents the response of the embodiment of FIG. Curves 24, 26
Compared to and 28, curve 30 shows a smooth frequency response and an improved response at low frequencies.

[0015] The earcup according to the present invention is advantageous over conventional earcups because of its port and resistive path configuration, which allows for active damping and significantly reduces the size of the rear cavity. This feature
In addition, for a given earcup size, the front cavity becomes larger and improves passive damping. The smooth frequency response makes it easier to use simplified electronics and combine it with more efficient driver operation, which is particularly advantageous in battery-powered active noise reduction headsets.
Enables a significant reduction in power consumption.

Other embodiments are within the scope of the following claims.

[Brief description of the drawings]

FIG. 1 is a plan view of a noise reduction headset.

FIG. 2 is a schematic sectional view of an ear cup embodying the present invention.

FIG. 3 is a schematic sectional view of an ear cup embodying the present invention.

FIG. 4 is a schematic sectional view of an ear cup embodying the present invention.

FIG. 5 is a perspective view of a module according to the present invention.

FIG. 6 is a sectional view showing another embodiment of the module according to the present invention.

FIG. 7 is a graph showing the relationship between driver response and frequency for the modules of FIGS. 6A-6D.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Active noise reduction module 12 Enclosure 14 Rear cavity 14 16 Port 17 Acoustic resistance opening 18 Driver 19 Passage 21 Sound emission diaphragm 22 Microphone 50 Ear cup part (ear cup shell) 52 Front cavity 53 Damping material 54 Comfort pad 56 Headband 58 Earcup structure

Claims (16)

[Claims] 1. A module suitable for use in an active noise reduction headset, comprising: an enclosure having a separating wall;
An enclosure characterized by compliance from the exterior of the enclosure; a driver having a diaphragm; a port connecting the interior and the exterior forming a resonant circuit resonating at a resonant frequency in cooperation with the compliance. A module comprising: a port having a mass to be changed; and a resonance damper coupled to the resonance circuit. 2. The module according to claim 1, wherein the resonance damper includes an acoustic resistance opening connecting the inside and the outside. 3. The module of claim 2, wherein said port and said acoustically resistive opening connect said interior and said exterior in parallel. 4. The module according to claim 2, wherein said port and said acoustically resistive aperture connect said interior and said exterior in series. 5. The module according to claim 2, further comprising a microphone having a pickup surface, wherein the microphone is mounted near an outer edge of the diaphragm. 6. The module according to claim 5, wherein a pickup surface of the microphone is oriented perpendicular to an axis of the driver. 7. The module according to claim 1, further comprising a microphone having a pickup surface, wherein the microphone is mounted near an outer edge of the diaphragm. 8. The module according to claim 7, wherein the pickup surface of the microphone faces radially inward. 9. The module of claim 1, wherein said interior has a volume of less than about 20 cc. 10. An active noise reduction headset, comprising: an earcup surrounding a first cavity and a compliant second cavity, wherein the first and second cavities are separated by a divider. A separate earcup; a comfort pad configured and arranged to seal the earcup from the side of the user's head; a driver having a diaphragm mounted therein; and a second cavity and the earcup. A port for connecting an external region, wherein said second port coupled to said resonator;
An active noise reduction headset, comprising: a port having a mass that cooperates with the compliance of the cavity of the above to form a resonant circuit; 11. The active noise reduction headset according to claim 10, wherein the resonance damper connects the second cavity and an external region of the earcup, and includes an acoustic resistance opening. set. 12. The active noise reduction headset according to claim 11, wherein the port and the acoustic resistance path connect the second cavity and the region in parallel. 13. The active noise reduction headset of claim 11, wherein the port and the acoustic resistance path connect the second cavity and the regional environment in series. 14. The active noise reduction headset according to claim 10, further comprising a microphone in the first cavity. 15. The active noise reduction headset of claim 14, wherein said microphone is mounted near an outer edge of said diaphragm. 16. The active noise reduction headset of claim 12, wherein the split comprises a module wall, the module surrounding the second cavity, the port and the acoustic resistance. An active noise reduction headset, wherein the module is removably integrated into the earcup such that an opening connects the second cavity and the region through an opening in the earcup.