EP3340646A1

EP3340646A1 - Listening device with noise suppression

Info

Publication number: EP3340646A1
Application number: EP16206279.8A
Authority: EP
Inventors: Jacob Reimert
Original assignee: GN Audio AS
Current assignee: GN Audio AS
Priority date: 2016-12-22
Filing date: 2016-12-22
Publication date: 2018-06-27

Abstract

A wearable listening device (301), such as a headset, comprising: an electro-acoustic transducer (302); a housing (303) accommodating the electro-acoustic transducer (302); and a flexible wearing support (304) attached to the housing (303) and configured to hold the housing in place on or over a wearer's at least one ear during normal use of the wearable listening device. A weight member (301) is suspended by a suspension member (302) which is attached to or integrated with the housing; wherein the suspension member (302) is configured to passively transfer vibrations from the housing (303) to the weight member (301) and to vibrate the weight member (301) to counteract at least some resonance vibrations of the housing (303).

Description

The claimed invention relates to a wearable listening device, such as a headset, comprising: an electro-acoustic transducer such as a speaker; a housing, such as an ear-cup, accommodating the electro-acoustic transducer; and a flexible support, such as a headband, attached to the housing and configured to hold the housing in place on or over a wearer's at least one ear during normal use of the wearable listening device.
A force acting on the wearable listening device, such as a force caused by sound pressure in the environment surrounding the wearable listening device, or such as a force caused by vibration of the speaker when driven by an electric signal, gives the housing oscillating kinetic energy which can be observed as mechanical vibration of the wearable listening device including the housing accommodating the electro-acoustic transducer. Measurements thereof have been reported in the prior art. As also reported, many headsets suffer from the fundamental mechanical resonance created by the weight of the headset's ear-cups and the spring force from its headband combined with the spring force of the ear-pads. This resonance may be triggered by ambient noise applying acoustical force to the ear-cups and/or by vibration of the speaker at or near the specific resonance frequency. The problem can be somewhat reduced by the use of Active Noise Cancellation (ANC), but this cannot completely remove the problem.
Especially, relatively low-frequent and high-power sound pressures, e.g. from heavy machines, may excite mechanical vibration of the housing positioned on or over a wearer's ears causing excessive vibration of the housing at the resonance frequency, which in turn may be observed as an excessive sound pressure at or about the resonance frequency. This is not a desired property of a headset or any other listening device.

RELATED PRIOR ART

WO 2000/035243-A2 (assigned on its face to University of Southampton) describes that in order to reduce noise reaching the user's ears, a headset shell is connected to a vibration actuator which is controlled to reduce the net vibration of the headset shell. The vibration actuator can be a piezo-electric actuator or an electro-mechanical actuator. The vibration actuator may be connected directly to the body of the shell, or it may be positioned between the periphery of the shell and an annular cushion or it may be mounted on a headband. The controller for the vibration actuator may utilise a feedback signal from a vibration sensor positioned on the headset shell and/or a feedback signal from a microphone positioned in the cavity of the headset shell. The vibration sensor comprises an accelerometer and an integrator arranged to integrate the output of the accelerometer.
The controller includes all the amplifiers required for the vibration actuator and a control filter, such as a filter having a gain which is not constant with frequency, that will result in a reduced vibration at the ear-shell within a frequency range.
US 8,295,530 (assigned on its face to Sennheiser Electronic Gmbh) describes headphones comprising a headband having a first and second end attached to respective first and second earpieces. The headband comprises a first and second spring layer and an intermediate dampening layer arranged between the first and second spring layer. Accordingly, the dampening layer, which may be a plastics layer, acts as a dampening element. By means of the dampening element parallel to the spring, the entire system is damped and a rise of the resonance can be avoided. Accordingly, any sound or oscillation, which results from headband resonance, is reduced or suppressed.
The article "Novel Active Noise-Reducing Headset Using Earshell Vibration Control" by Joao Boaz Rafaely and Paolo Gardonio Carrilho, October 2002, describes that conventional active noise-reducing (ANR) headsets use passive attenuation at high frequencies and loudspeaker-based active noise cancelling at low frequencies to achieve broadband noise reduction. There is described an ANR headset in which the external noise transmitted to the user's ear via earshell vibration is reduced by controlling the vibration of the earshell using vibration actuators acting against an inertial mass or the earshell headband. The vibration actuator is attached to the earshell and produces a force (vibration) that opposes the force (vibration) imposed by the external noise, therefore reducing earshell vibration.
However, the prior art solutions involve relatively high cost that cannot always be allowed in production of a headset or another type of listening device, such as those sold on a high-volume consumer electronics market. Also, some known solutions require that electric power be available in the listening device, and they may further be difficult to control and may thus in some cases even increase mechanical vibration of the housing.

SUMMARY

Sound pressures originating from sound sources in the environment surrounding the listening device as well as vibration of the speaker may excite mechanical vibration of the housing positioned on or over a wearer's ears causing excessive vibration of the housing, which in turn may be observed as an excessive sound pressure acting on the wearer's ears.
It is an object of the invention to device low-cost alternatives to the prior art solutions for reducing a sound pressure acting on the wearer's ears by reducing earcup vibrations excited by sound sources in the environment surrounding the listening device. It is a further objective to device solutions that are independent of electric power. It is a further objective to device solutions that are easy to control.
There is provided a wearable listening device, such as a headset, comprising: an electro-acoustic transducer; a housing accommodating the electro-acoustic transducer; a flexible wearing support attached to the housing and configured to hold the housing in place on or over a wearer's at least one ear during normal use of the wearable listening device; and a damper having a weight member passively suspended by a suspension member, which is attached to or integrated with the housing; wherein the suspension member is configured to passively transfer vibrations from the housing to the weight member and to vibrate the weight member such that the damper functions as a tuned mass damper counteracting at least some resonance vibrations of the housing.
Since vibrations are transferred from the housing to the suspension member, which thereby vibrate the weight member to counteract at least some resonance vibrations of the housing, the housing vibrates less at the respective resonance frequency or frequencies and causes a lower vibration-induced sound pressure at the wearer's ear. Vibrations may be reduced in terms of a smaller maximum amplitude and/or in terms of a shorter decay time.
Since the weight member is passively suspended, no electric components, such as sensors, microprocessor-based controllers or electro-mechanical actuators, are needed for the purpose of reducing the resonance vibrations. This keeps costs down and has the advantage that electric power is not needed. Especially for battery-powered listening devices, it is a great advantage that battery power is not drained by such electric components for that purpose.
Vibrations of the housing may be reduced most effectively at and about a resonance frequency of the listening device at which the housing (without the damper) vibrates with a significantly greater amplitude, such as by +3dB or more, than at other frequencies in a direction normal to a sagittal plane with respect to the wearer's head. Such a resonance frequency may also be denoted a fundamental resonance frequency.
A tuned mass damper functions according to a well-known principle. A weight member is movably suspended and mechanically connected via a suspension member to an object subjected to unwanted vibrations. The unwanted vibrations may be characterized by a vibration frequency and a vibration direction. The suspension member is configured to transfer vibrational force in the vibration direction from the object to the weight member. The weight member and the suspension member are together configured such that they have a salient damper resonance at the vibration frequency with respect to vibrations in the vibration direction. Typically, the suspension member is configured with relatively low loss and relatively high compliance, such that a vibration of the weight member is easily excited by vibrations of the object and such that the amplitude of the vibration of the weight member in the vibration direction is substantially larger than the amplitude of the corresponding vibration of the object. Thus, the suspension member counteracts the vibration of the object by transferring vibration energy from the object to the weight member. Over time, at least some of the vibration energy stored in the weight member is transformed into heat energy in the suspension member.
It is appreciated that since the housing is attached to the flexible wearing support and usually is equipped with foam cushions or the like for softly fitting on or around the wearer's ears, the housing may engage in complex vibration patterns. It is typically particularly annoying for the wearer when the vibration pattern has large amplitudes in a direction perpendicular to a sagittal plane with respect to the wearer's head and/or parallel to an axial movement of a membrane of the electro-acoustic transducer comprised by the electroacoustic transducer, i.e. a direction corresponding to the direction x in fig. 1, since such vibrations may cause loud vibration noise at the wearer's ear. Such annoying vibrations may predominantly occur at a resonance frequency of the listening device that is determined by mechanical properties of the housing, the headband and their mutual mechanical coupling. Since complex vibration patterns may be observed, the resonance frequency is sometimes denoted a fundamental resonance frequency, which distinguish the fundamental resonance frequency over a multitude of other, smaller amplitude, vibrations of the housing or its components, which typically occur at higher frequencies.
In the damper, the suspension of the weight member is passive, meaning that during normal use of the listening device, all kinetic energy of the weight member is supplied passively through the damper's suspension. Accordingly, the damper's suspension member is passive. Note that in some cases, which do not normally occur during use of the listening device, the weight member may receive kinetic energy through or from other parts of the listening device. Such cases may occur e.g. when the listening device is subjected to extremely large vibrations or mechanical shocks, or when the listening device is in a shipping configuration wherein one or more transportation fixtures restrain the damper and thus protect it from extremely large vibrations or mechanical shocks.
The suspension member, which is attached to or integrated with the housing, establishes a mechanical coupling between the housing and the weight member through which vibration energy can be transferred. The suspension member may be attached to or integrated with the housing to provide a flexible mechanical coupling or a hinged mechanical coupling.
The weight member may be attached to or integrated with the suspension member. In some embodiments, the weight member, the suspension member and the housing, or at least portions thereof, are integrally moulded in one piece or assembled from multiple moulded pieces. In some embodiments, the suspension member and at least a part of the housing are integrated by moulding. In some embodiments, the weight member comprises a first portion and a second portion, wherein the first portion is integrated by moulding with the suspension member, which is integrated by moulding with at least a part of the housing, and wherein the second portion has a higher weight density than the first portion. In some embodiments, the first portion is made from a plastics material such as ABS. The second portion may e.g. be made from a metal, from a plastics material, or a plastics material with integrated metal pieces.
In some embodiments, the damper is configured such that the weight member is easily excited by vibrations of the housing at a resonance frequency of the wearable listening device in a vibration direction and such that the amplitude of the vibration of the weight member in the vibration direction is substantially larger than the amplitude of the corresponding vibration of the housing.
Since the damper is inherently passive and thus works without electric power, the weight member may vibrate at all times without consuming electric power, also when electronic circuitry of the listening device is switched off.
To make the damper counteract at least a portion of the resonance vibrations of the housing, the damper, and thus the combination of the suspension member and the weight member, may be 'tuned' to have a resonance frequency, which coincides with or is located relatively close to a fundamental resonance frequency of the housing. Note that it may be necessary to remove the weight member and the suspension member in order to determine such a fundamental resonance frequency of the housing and/or the magnitude of that resonance vibration. Various methods for such 'tuning' are known in the art. For instance, tuning may be performed according to the so-called 'tuned mass damper theory', e.g. as described by Den Hartog. The frequency of the damper resonance may be an inherent property of the mechanical configuration of the damper, such that tuning is in principle comprised by the process of designing the damper. Alternatively or additionally, tuning may comprise one or more tuning actions comprising altering mechanical properties of the damper to achieve a frequency of the damper resonance within a predefined frequency range and/or to achieve a predefined relationship between the frequency of the damper resonance and a resonance frequency of the wearable listening device. One or more of such tuning actions may be performed at any time during production of the damper, of the housing and/or of the wearable listening device, and/or at any later time.
Thus, if tuned properly, the maximum vibration amplitude or vibration decay time of the housing will be significantly lowered, compared to an identical listening device without a damper, since a large portion of the vibration energy thereof is transferred to the damper.
At least the suspension member has an equivalent spring coefficient and a damper coefficient. Both coefficients may be designed, dimensioned and/or altered during tuning of the damper, e.g. by designing, dimensioning and/or altering shape and/or material properties of the suspension member. In some embodiments, the suspension member is implemented as a spring and a resistive element.
In some embodiments, the damper causes the vibration of the housing or a portion thereof at a resonance frequency to have a damping ratio of about 1, such as greater than 0.6 and less than 2. The damping ratio is a dimensionless measure describing how oscillations in a system decay after a disturbance. The damping ratio is a measure indicating how quickly oscillations decay from one bounce to the next.
The weight member preferably weighs less than the housing excluding the weight member; the weight member may weigh less than about 15% of the housing excluding the weight member, such as e.g. about 5-10% thereof.
In some embodiments, the electro-acoustic transducer comprises a membrane configured to provide a sound pressure by moving axially along a centre axis, and the weight member is suspended to move along a path with a tangent, which is substantially parallel to the centre axis. Thereby, disturbing sound pressures acting on the wearer's ear are effectively suppressed. The suspension member may be attached flexibly or pivotally to the housing. The damper may move as a pendulum.
In some embodiments, the suspension member is an elongate member, which extends from an inner wall of the housing. The suspension member and/or the weight member may be integrated with the housing or a component thereof. Thereby, since the housing is often produced by moulding, the vibration damping may be implemented at low cost.
In some embodiments, the suspension member extends from the inner wall, at its one end, to the weight member at its other end, which is movable. In other embodiments, the suspension member, which may be a beam, has both of its ends extending from the inner wall at different positions. In some embodiments, the suspension member is a straight member, and in other embodiments, it is a curved member. The weight member may be attached to or integrated at a central or middle portion of the suspension member.
In some embodiments, the electro-acoustic transducer comprises a membrane with a centre axis along which the membrane moves to provide a sound pressure, and the suspension member extends radially from the inner wall of the housing within a quarter of a turn, within a sixth of a turn, or within an eighth of a turn, about the centre axis, from an attachment point at which the flexible wearing support is attached to the housing. Thereby vibration damping is coupled to the housing close to the attachment point at which the flexible wearing support is attached to the housing. The flexible wearing support may be attached by e.g. a swivel, a gimbal, a hinge and/or a flexible member.
In some embodiments, the wearable listening device comprises multiple suspension members extending radially from the inner wall of the housing, and at least one of the suspension members extends radially from the inner wall of the housing at an attachment point located within a quarter of a turn, about the centre axis, from a point radially opposite the attachment point at which the flexible support is attached to the housing. Thereby vibration damping is coupled to the housing, radially opposite the attachment point at which the flexible wearing support is attached to the housing.
In some embodiments, the damper is configured as a hammer with a head and a flexible shaft. The head, or the weight member, may e.g. be configured with a mainly spherical shape, or an elongate shape, such as an elongate shape, which extends mainly along the centre axis mentioned above.
In some embodiments, the weight member has an annular shape. The weight member may have a bore that at least partially accommodates the electro-acoustic transducer and/or other components of the listening device. This may allow for closer and tighter integration of components of the listening device, such as within the housing. The weight member may be arranged with its bore axis being substantially parallel with or coinciding with a centre axis of the electro-acoustic transducer.
In some embodiments, the damper comprises a first suspension member extending radially from the housing to the weight member and a second suspension member extending axially from the housing to the weight member. Thereby, the weight member may be kept in place in the radial direction by the first suspension member and be vibrated in the axial direction by the second suspension member. The first suspension member may be embodied as a spring or act as a spring. The second suspension member may be embodied as a spring and/or a resistive element. The first suspension member may have a larger compliance than the second suspension member for movement of the weight member in the axial direction. The first suspension member may have a substantially lower compliance for movement of the weight member in the radial direction than for movement of the weight member in the axial direction.
In some embodiments, the damper comprises a first suspension member and a second suspension member extending axially from axially opposite ends of the weight member. Thereby the weight member is suspended at opposite ends, thereby making it possible to reduce undesired deflection and undesired vibration of the weight member in a direction transverse to the axial direction. The weight member may e.g. be configured as a sphere or a box or as an annular member, which is suspended at multiple positions, e.g. at two, three or more positions. The first suspension member and the second suspension member may each be selected from the group of: springs, resistive elements and shock absorbers.
In some embodiments, the suspension member comprises a spring and a resistive element. The suspension member may be configured as a shock absorber. The resistive element may be of the dashpot type. A dashpot is a mechanical device, a resistive element, which resists motion via viscous friction. The resulting force is proportional to the velocity, but acts in the opposite direction, thereby slowing the motion and absorbing energy. Comparatively, the spring acts to resist displacement.
In some embodiments, the suspension member is configured as a spider with a body from which peripheral arms extend outwards to distal ends, which are attached to one or more weight members. In general, the suspension member may have elongate arms. The arms may have a varying cross-section to obtain desired spring and/or damper coefficients. In some embodiments, the arms have a concave longitudinal section.
In some embodiments, a resonance frequency of the damper is in the range of 20-120 Hz, and a resonance frequency of the wearable listening device excluding the damper is in the range of 20-80 Hz.
In some embodiments, the wearable listening device comprises an active noise reduction circuit operating by electronic control of the electro-acoustic transducer to reduce noise at frequencies above 100 Hz, such as above 400 Hz.
In some embodiments, the listening device comprises an active noise reduction or active noise cancellation circuit, which drives an electro-acoustic transducer in anti-phase with a noise signal picked up by one or more microphones. The active noise reduction or active noise cancellation may operate by electronic control of the electro-acoustic transducer to reduce noise at frequencies above 100 Hz, such as above 400 Hz.
In some embodiments, the listening device comprises a transducer, such as a microphone, for receiving a wearer's voice and/or a wireless receiver for receiving a sound signal wirelessly, e.g. according to the Bluetooth or DECT standard.
In some embodiments, the listening device comprises a battery or a battery compartment for accepting a battery. The battery may supply electric power to one or more of a wireless receiver, a transducer, an amplifier and an active noise reduction or active noise cancellation circuit.

BRIEF DESCRIPTION OF THE FIGURES

A more detailed description follows below with reference to the drawing, in which:

fig. 1 shows a first headset;
fig. 2 shows an ambient noise to ear transfer function via an earcup;
fig. 3 shows a second headset with a weight suspended to vibrate to counteract a vibration of an earcup;
fig. 4 shows an ambient noise to ear transfer function via an earcup;
figs. 5a and 5b show a first earcup in a side view and in an axial view, respectively;
fig. 6 shows a second earcup in an axial view;
fig. 7 shows a third earcup in an axial view;
figs. 8a and 8b show a fourth earcup in an axial view and in a side view, respectively;
fig. 8c shows an annular weight member integrated with a spider-shaped suspension member;
fig. 9 shows a fifth earcup in a side view; and
fig. 10 shows a sixth earcup in a side view.

DETAILED DESCRIPTION

Fig. 1 shows a first headset. The first headset 101 comprises a left-hand side earcup 105 and a right-hand side earcup 105', which each accommodates an electro-acoustic transducer (not shown) for reproducing an audio signal acoustically towards an ear of a wearer. The earcups comprise respective housings 103 and 103', accommodating the electro-acoustic transducers, and cushions 106 and 106' for softly fitting to and resting against the wearer's ears or head. The earcups are held in place by a flexible wearing support 102 extending between the earcups over the wearer's head during normal use.
A sound pressure from a source in the environment surrounding the headset is designated 'SP'. The sound pressure will propagate through the air and may originate from a source such as a machine. The sound from such a source or sources may be denoted ambient noise. An axial direction is designated 'x' and a radial direction is indicated by 'y' or 'z'.
Fig. 2 shows a transfer function for transfer of ambient noise to the wearer's ear via an earcup. The ambient-noise-to-ear transfer function, illustrated by curve 201, is shown in a double-logarithmic diagram with frequency [Hz] along the abscissa and magnitude [dB] of the transfer function along the ordinate. The earcup works as a low-pass filter and begins to roll off at frequencies above 200-400 Hz. Thus, the earcup with its housing and cushion attenuates ambient noise - mainly at frequencies above 200-400 Hz.
At a relatively low frequency, say a frequency below 100 Hz, many earphones have a fundamental resonance frequency 202. At such a fundamental resonance frequency, which may be located about 50 Hz, ambient noise - or any other type of sound, such as loud music - or vibration of the electro-acoustic transducer - may excite vibrations of the earcup or portions thereof. These vibrations work constructively to build up a sound pressure in the earcup above the ambient sound pressure level at that frequency. This may significantly degrade the comfort of wearing the headset.
Fig. 3 shows a second headset with a weight passively suspended to vibrate in a manner counteracting a vibration of an earcup. The second headset 307 comprises a left hand side earcup 105 and a right hand side earcup 105', which each accommodates an electro-acoustic transducer 302 and 302' for reproducing an audio signal acoustically towards an ear of a wearer. The earcups comprise respective housings 303 and 303', accommodating the electro-acoustic transducers, and cushions 106 and 106' for softly fitting to and resting against the wearer's ears or head.
Weight members 301 and 301' are passively suspended by respective suspension members 302 and 302', which are attached to or integrated with the respective housings 303 and 303'. The suspension members 302 and 302' are configured to passively transfer vibrations from the respective housings 303 and 303' to the respective weight members 301 and 301' and to vibrate the weight members 301 and 301' in a manner counteracting at least some resonance vibrations of the housings 303 and 303'. Each of the weight members and its respective suspension member thus function as a tuned mass damper.
Fig. 4 shows a transfer function for transfer of ambient noise to the wearer's ear via an earcup. The ambient-noise-to-ear transfer function, illustrated by curve 201, is also here shown in a double-logarithmic diagram with frequency [Hz] along the abscissa and magnitude [dB] of the transfer function along the ordinate. As mentioned above, the earcup works as a low-pass filter and begins to roll off at frequencies above 200-400 Hz. Thus, the earcup with its housing and cushion attenuates ambient noise - mainly at frequencies above 200-400 Hz.
It is also here illustrated that at a relatively low frequency, say at 50 Hz, the headset has a fundamental resonance frequency 202. However, when the weight member 301; 301' is passively suspended to vibrate as described herein, the ambient noise to ear transfer function at such a fundamental frequency may be attenuated by the movements of the weight member.
Figs. 5a and 5b show a first earcup in a side view and in an axial view, respectively. The flexible wearing support 102 is attached to the housing 303 at an attachment point 104 and in this embodiment is shown as being pivotally mounted. The weight member 301 is suspended by the suspension member 302, which is integrated with the housing 303 and extends radially, as shown in fig. 5b, from an inner wall of the housing 303. The suspension member 302 has a varying cross-section over its length and has a concave longitudinal section.
For the sake of completeness, it is noted that electronic components and an electro-acoustic transducer are not shown in this illustration.
Fig. 6 shows a second earcup in an axial view. The flexible wearing support is attached to the housing by a first pivot mount 601 enabling rotation about the shown y-axis and by a second pivot mount 602 enabling rotation about the shown z-axis. In this embodiment, three dampers 603, 604 and 605, each comprising a weight member suspended by a suspension member, extend radially from an inner wall of the housing 303. The three dampers 603, 604 and 605 are spaced apart by approximately 120 degrees with respect to a centre axis x. The three dampers are shown to have the same shape; however, they may be different from each other, e.g. tuned to different resonance frequencies. The dampers are shown as extending from a smallest of cylinder portions constituting the housing 303. However, the dampers may be positioned at other locations with respect to the housing 303.
Fig. 7 shows a third earcup in an axial view. In this embodiment, two dampers 701 and 702, each comprising a weight member suspended by a suspension member, extend radially from an inner wall of the housing 303. As shown, the dampers 701 and 702 are spaced apart by approximately 180 degrees with respect to a centre axis x. However, they may be arranged closer to each other e.g. spaced apart by approximately 90 degrees or another angular distance.
Figs. 8a and 8b show a fourth earcup in an axial view and in a side view, respectively. In this embodiment, the weight member is designated by reference numeral 802 and has an annular shape. As shown, the weight member 802 is arranged with its bore axis substantially parallel with or coinciding with a centre axis x of the electro-acoustic transducer 302. The bore of the weight member 802 may at least partially accommodate the electro-acoustic transducer 302 and/or other components of the earcup.
In this embodiment, the annular weight member 802 is passively suspended by a spider-shaped suspension member, however the annular weight member 802 may be suspended in other ways as described herein.
Fig. 8c shows a damper comprising an annular weight member integrated with a spider-shaped suspension member. The spider-shaped suspension member has a body 801, such as a substantially circular body, from which arms 803 extend outwards to distal ends, which are attached to or integrated with the annular weight member 802. In some embodiments, each of the arms 803 may carry a respective weight member. The body 801 is configured for attachment to a housing of a listening device, such as the housing 303 of figs. 8a and 8b.
Fig. 9 shows a fifth earcup in a side view. In this embodiment, the damper comprises first suspension members 901 and 903 and second suspension members 902 and 904 extending axially from axially opposite sides of an annular weight member 905 shown in a cross-section. In some embodiments, the first suspension members 901 and 903 and second suspension members 902 and 904 may be embodied as shock absorbers comprising a spring and a resistive element. In some embodiments, the first suspension members 901 and 903 are configured as springs and the second suspension members 902 and 904 are configured as resistive elements. In some embodiments, three pairs of a first suspension member 901 and a second suspension member 902 are spaced apart by approximately 120 degrees with respect to a centre axis x of the electro-acoustic transducer 302 to suspend the weight member at three locations.
Fig. 10 shows a sixth earcup in a side view. In this embodiment, the damper comprises first suspension members 1002 and 1004 extending radially from the housing 303 to one or more weight members, such an annular weight member 905 shown in a cross-section, and second suspension members 1001 and 1003 extending axially from the housing 303 to the weight member 905. The first suspension members 1002 and 1004 may be embodied as springs and the second suspension members may be embodied as flexible arms extending from an inner wall of the housing 303.

Claims

A wearable listening device (307), such as a headset, comprising:
- an electro-acoustic transducer (302);

- a housing (303) accommodating the electro-acoustic transducer (302); and

- a flexible wearing support (102) attached to the housing (303) and configured to hold the housing in place on or over a wearer's at least one ear during normal use of the wearable listening device;
CHARACTERIZED in comprising:
a damper having a weight member (301) passively suspended by a suspension member (302), which is attached to or integrated with the housing (303);

wherein the suspension member (302) is configured to passively transfer vibrations from the housing (303) to the weight member (301) and to vibrate the weight member (301) such that the damper functions as a tuned mass damper counteracting at least some resonance vibrations of the housing (303).
A wearable listening device according to claim 1, wherein the damper is configured such that a vibration of the weight member (301) is easily excited by vibrations of the housing at a resonance frequency of the wearable listening device in a vibration direction and such that the amplitude of the vibration of the weight member in the vibration direction is substantially larger than the amplitude of the corresponding vibration of the housing (303).
A wearable listening device according to claim 1 or 2,
wherein the electro-acoustic transducer (302) comprises a membrane configured to provide a sound pressure by moving axially along a centre axis (x); and
wherein the weight member (301) is suspended to move along a path with a tangent which is substantially parallel to the centre axis (x).
A wearable listening device according to any of claims 1-3, wherein the suspension member (302) is an elongate member, which extends from an inner wall of the housing.
A wearable listening device according to any of claims 1-4,
wherein the electro-acoustic transducer (302) comprises a membrane with a centre axis (x) along which the membrane moves to provide a sound pressure; and
wherein the suspension member (302) extends radially from the inner wall of the housing within a quarter of a turn, about the centre axis, from an attachment point at which the flexible wearing support (102) is attached to the housing (303).
A wearable listening device according to any of claims 1-5,
comprising multiple suspension members extending radially from the inner wall of the housing; and
wherein at least one of the suspension members (302) extends radially from the inner wall of the housing at an attachment point located within a quarter of a turn, about the centre axis (x), from a point radially opposite the attachment point at which the flexible support (102) is attached to the housing (303).
A wearable listening device according to any of claims 1-3, wherein the damper is configured as a hammer with a head and a flexible shaft.
A wearable listening device according to any of claims 1-6, wherein the weight member (301) has an annular shape.
A wearable listening device according to any of claims 1-8, wherein the damper comprises a first suspension member (1002) extending radially from the housing (303) to the weight member (905) and a second suspension member (1001) extending axially from the housing (303) to the weight member (905).
A wearable listening device according to any of claims 1-9, wherein the damper comprises a first suspension member (901) and a second suspension member (902) extending axially from axially opposite ends of the weight member (905).
A wearable listening device according to any of claims 1-10, wherein the suspension member comprises a spring and a resistive element.
A wearable listening device according to any of claims 1-11, wherein the suspension member is configured as a spider with a body (801) from which peripheral arms (803) extend outwards to distal ends, which are attached to one or more weight members (802).
A wearable listening device according to any of claims 1-12, wherein a resonance frequency of the damper is in the range of 20-120 Hz and wherein a resonance frequency of the wearable listening device excluding the damper is in the range of 20-80 Hz.
A wearable listening device according to any of claims 1-13, comprising an active noise reduction circuit operating by electronic control of an electro-acoustic transducer (302) to reduce noise at frequencies above 100 Hz, such as above 400 Hz.