WO2012146922A1

WO2012146922A1 - Earphone apparatus

Info

Publication number: WO2012146922A1
Application number: PCT/GB2012/050909
Authority: WO
Inventors: Paul Darlington; Mark Donaldson
Original assignee: Soundchip Sa
Priority date: 2011-04-27
Filing date: 2012-04-25
Publication date: 2012-11-01
Also published as: GB201318877D0; GB2503853A; GB201107007D0; GB2503853B

Abstract

Earphone apparatus (10) comprising: a transducer (40)(50)(90)(100) used in processing an audio signal, generating an acoustic output to a user, or tracking movement of a head- mounted part of the earphone apparatus (10); wherein the transducer (40)(50)(90)(100) is further configured to provide to a signal processor (70) an input signal for altering operation of the earphone apparatus (10) or a device connected to the earphone apparatus, the input signal being generated in response to a predetermined user interaction with the earphone apparatus (10) detectable by the transducer (40)(50)(90)(100).

Description

TITLE: EARPHONE APPARATUS

DESCRIPTION

The present invention relates to earphone apparatus (e.g. apparatus comprising at least one earphone), and particularly but not exclusively to earphone apparatus configured to provide noise reduction or tracking of a user's head position. Earphones (e.g. circumaural or supra-aural earphones of the type connected together by a headband to form headphones or in-ear/in-the-canal earphones configured to be placed at the entrance to or in the auditory canal of a user's ear) are well known in the art. Active earphone apparatus often feature in addition to a simple power on/off switch control inputs used to switch between different operating modes (such as enabling or disabling active noise reduction) or to adjust an operating parameter (such as an equaliser setting or volume control).

Increasingly, earphone apparatus for portable devices are also equipped with means to control other devices to which they are connected (such as "MP3 Players"), providing play/pause control, fast-forward control, track selection and the like.

These controls are actuated by the wearer through manual operation of a physical switch on the body of the earphones or through electronic equivalents of a mechanical switch (capacitive or inductive touch or proximity detectors, etc).

The provision of such switches and control electronics associated with them also is supporting the development and deployment of "gestural" control strategies, in which the wearer signals her/his intention through a moving gesture of the hand or finger on or near the switches. The gesture is recognised by electronics in the earphones and the appropriate control command is issued. It is seen that support of these switching and control functions requires the head- or earphone is provided with a plurality of mechanical (or other) switches or sensors with which to detect the wearer's manual inputs and a layer of subsequent electronics to interpret these inputs and provide interface to other electronic systems or devices.

Figure 1 shows an example of a prior art supra-aural wireless headphone 1 for stereo Bluetooth (A2DP) application comprising a vestigial "headband" 2, which is worn behind the head/neck and which passes over the pinnae to support the weight of the earpieces 3, 4. One of the earpieces 3 includes a housing provided with an array of five mechanical switches 5-9. These switches are arranged to provide power on/off control for the device as well as volume up/down (switches 7 and 8) and track seek forward / backward (switches 5 and 6). Switch 9 provides a context-dependent acknowledge input.

The present applicant has identified the need for an improved technique for providing mode or parameter control implementable using potentially fewer components than the prior art.

In accordance with the present invention, there is provided earphone apparatus comprising: a transducer (e.g. means operable as a sensor) used in processing an audio signal, generating an acoustic output to a user, or tracking movement of a head-mounted part of the earphone apparatus; wherein the transducer is further configured to provide to a signal processor an input signal for altering operation of the earphone apparatus or a device connected to the earphone apparatus, the input signal being generated in response to a predetermined user interaction with the earphone apparatus detectable by the transducer.

In this way, earphone apparatus is provided in which the operation of dedicated mechanical control switches (or their equivalents) may be replaced by outputs of one or more sensors already present in the device. The apparatus of the present invention retains the electronics required to support the "physical" interface to the user's manual inputs but, in removing the requirement for physical switches (or their equivalent), may confer advantages in terms of cost and space savings. In one embodiment, a plurality of different input signals may be derived by reference to a duration of or length of time between each user interaction with the earphone apparatus.

In one embodiment, the earphone apparatus may comprise at least one earphone (e.g. at least one circumaural or supra-aural earphone of the type used in headphones or at least one in-ear or in-the-canal device)). In one embodiment, the earphone apparatus comprises a pair (e.g. stereo pair) of earphones. In one embodiment, the earphone apparatus may comprise a headset including a microphone for a user to speak into (e.g. for use with a mobile telephone).

In one embodiment the input signal is a command signal (e.g. for changing a mode of operation of the earphone apparatus or a device connected to the earphone apparatus, or for adjusting an operating parameter of the earphone apparatus or a device connected to the earphone apparatus). The input signal may be transmitted to the signal processor over a wired or wireless connection. The signal processor may form a part of the earphone apparatus and may be located inside or outside of the at least one earphone.

In one embodiment the connected device is an audio source supplying an audio signal to the earphone apparatus.

In a first embodiment the transducer is an electro-acoustic transducer. For example, the transducer may be a microphone or an electro-acoustic driver for generating an acoustic output to a user. In the case of a microphone, the microphone may be a sensing microphone for use in noise reduction, monitoring, linearizing or any other active function. In one embodiment, the sensing microphone may be configured to sense external sound (e.g. ambient acoustic noise). In the case of apparatus comprising at least one earphone configured to be inserted at least in part into an auditory canal of a user's ear (e.g. an in-the- canal earphone), the sensing microphone may be configured to sense sound present in the auditory canal of the user's ear (e.g. for use in reducing occlusion effects). The sensing microphone may be configured to provide a feed- forward or feedback signal respectively to the or a further signal processor (e.g. dedicated Active Noise Reduction (ANR) processor) to reduce either external noise or occlusion noise. In one embodiment the microphone is a MicroElectrical-Mechanical (MEMs) microphone (or "silicon microphone").

In a second embodiment the transducer is an accelerometer used to track movement of a head-mounted part of the earphone apparatus (e.g. used to derive head position or other spatial information).

In a first embodiment, the predetermined user interaction with the earphone apparatus detected by the transducer may be movement of a part of the earphone apparatus (e.g. part on or adjacent the user's ear) relative to the user (e.g. relative to the user's head). In one embodiment movement of the part of the earphone apparatus (e.g. outer part) relative to the user is achieved by virtue of a compliant element (e.g. located between the outer part and the user's head) of the earphone apparatus (e.g. a compliant ear pad in the case of earphone apparatus comprising at least one circumaural or supra-aural earphone or a compliant tip or grommet in the case of earphone apparatus comprising at least one in-ear or in-the-canal earphone). In another embodiment movement of the part of the earphone apparatus relative to the user is achieved by virtue of elastic deformation of the user's outer ear.

In the case that the transducer is an electro-acoustic transducer, the predetermined user interaction with the earphone apparatus may generate an acoustic signal.

In a first embodiment, the acoustic signal is generated by movement of a part of the earphone apparatus relative to the user causing a change in pressure sensed by the electro- acoustic transducer. For example, in the case that the transducer is a sensing microphone configured to sense sound present in the auditory canal of the user's ear or an electro- acoustic driver acoustically coupled to the auditory canal of the user's ear, the predetermined user interaction with the earphone apparatus may be movement of the earphone apparatus relative to the user causing a change in volume of air in communication with the sensing microphone or electro-acoustic driver (and hence a change in pressure in the auditory canal of the user's ear). In a second embodiment, the acoustic signal is generated by a user interaction generating an acoustic wave (e.g. without any change in the volume of air in communication with a sensing microphone or electro-acoustic driver acoustically coupled to the auditory canal of the user's ear). For example, the acoustic signal may be generated by a user causing transient vibration of a part of the earphone apparatus. In one embodiment the earphone apparatus may be provided with outer surface features or internal features configured to enhance generation of the acoustic signal (e.g. to provide a detectable signature signal).

In the case that the transducer is an accelerometer, the predetermined user interaction with the earphone apparatus may be any movement capable of being sensed by the accelerometer (e.g. a user's touch causing movement of a part of the earphone apparatus). In one embodiment, the signal processor is configured to monitor for combinations of input signals (e.g. an input signal corresponding to a predetermined user interaction with the earphone apparatus involving movement of a part of the earphone apparatus relative to the user and an input signal corresponding to a predetermined user interaction with the earphone apparatus involving generation of an acoustic signal). The signal processor may be configured to act on the received input signals only if the combination of input signals is received within a predetermined time period (e.g. substantially simultaneously). In this way, the risk of unintentional input signals being generated during use of the earphone apparatus may be reduced.

The signal processor may be configured to process signals received from the transducer (e.g. prior to identifying an input signal in order to condition the signal). In one embodiment, the signal processor may be configured to filter signals received from the transducer (e.g. to remove signal components arising from reproduced sounds, ambient noise or head movement from those associated with the predetermined user interaction with the earphone apparatus). In one embodiment the signal processor may be configured to perform feature extraction or pattern recognition (e.g. to distinguish signal components arising from reproduced sounds, ambient noise or head movement from those associated with the predetermined user interaction with the earphone apparatus). In one embodiment, the signal processor may be configured to subtract from a received signal estimates of signal components arising from normal operation of the earphone apparatus. In one embodiment, the signal processor may be configured to subtract from a received signal estimates of signal components arising from movement of the user's head. In another embodiment, the signal processor may be configured to subtract from a received signal estimates of signal components arising from external noise (e.g. ambient noise including the user's own voice).

The earphone apparatus of the present invention may be used in any application in which personal listening is required.

In one embodiment, the earphone apparatus forms part of a hearing-aid.

In another embodiment, the earphone apparatus forms part of a headset including a microphone for a user to speak into (e.g. for use with a mobile telephone).

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 is a schematic view of a prior art pair of wireless headphones;

Figure 2 is a schematic illustration of generic earphone apparatus;

Figure 3 is a schematic representation of earphone apparatus in accordance with a first embodiment of the present invention; and

Figure 4 is a schematic representation of earphone apparatus in accordance with a second embodiment of the present invention.

Figure 2 shows generic earphone apparatus 10 comprising a substantially rigid body 20 which forms a mechanical and inertial framework for the components within. Body 20 is able to move with respect to the wearer's ear by virtue of a compliant element 30 which may comprise elements of an ear pad (in the case of a headphone) or grommet (in the case of an in-ear or in-the-canal earphone) which forms a partial acoustic seal to the ear. The compliance may also be due in part to elastic deformation of the wearer's outer ear.

Earphone apparatus 10 further comprises a "receiver" 40 (i.e. a miniature loudspeaker which generates sounds to be conducted to the ear). Additionally, an active device - particularly one incorporating active noise reduction using a "feedback" control topology - may include a microphone 50 sensitive to pressures inboard of the receiver and acoustically connected to the wearer's external auditory meatus. Both receiver 40 and the microphone 50 are in a substantially sealed volume of air 60, the volume of which is modulated by any deformation of the compliant element 30.

The system includes electronic components 70, which control and drive all functions and communicate with external devices, including the source of the audio media which are reproduced by the earphone apparatus through a (potentially bidirectional) interface 80 which may be implemented using wired or wireless means.

The system may include one or more microphones 90 arranged to be sensitive to external pressures. These microphones may be present to allow the wearer to monitor external sound or to allow the device to perform active cancellation of such sound by active noise reduction using a "feed-forward" control topology.

The system may include one or more accelerometers 100 arranged to derive head position information. This information may be used in (e.g.) gaming applications, in which sound can be arranged to appear to emanate from a physical source (such as a screen) which remains in a fixed location even when the wearer moves their head. Alternatively, the positional information may be used to allow the wearer to move their head within a virtual acoustic field and localise virtual sources therein.

The device depicted in Figure 2 is seen to include no sensors, switches or transducers provided for the purpose of providing an interface for manual control inputs from the wearer. It is, however, the purpose of the present invention to derive such connectivity by exploiting the signals produced from transducers 50, 90 & 100 (and - potentially - from the receiver 40 operating in concert with the control electronics 70).

In touching the body of the personal audio platform, contact between the wearer's hand and the body of the device will move said body. Such movement can be directly transduced (e.g. by the accelerometer(s) in Figure 2). Alternatively, movement will cause deformation of the compliant mounting, which will cause modulation of the partially sealed volume between the device and the ear, which will cause a pressure change in said volume. This pressure change can be transduced by appropriately positioned microphone(s) (such as microphone 50 in Figure 2). Finally, manual contact with the audio platform will generate direct sound which may be detected by microphones sensitive to such pressures (such as microphones 90 in Figure 2).

The signal components from any of the transducers resulting from manual inputs (as described above) will be present even in the case where the device is equipped with switches (or equivalent) designed to detect such manual interventions. Accordingly, the present invention exploits information already present within the system and does not provoke any changes to the core functionality of the device.

Figure 3 shows earphone apparatus 10' in which an acoustic signal generated in partially sealed volume of air 60' by the change of this volume are used (i.e. an acoustical embodiment). The output from the inboard microphone 50' is "split" within the electronics 70'. The microphone signal goes to the audio component of the electronics 70a, where it continues to be used for its principal purpose (e.g. for active feedback control of noise, monitoring or linearizing the response of receiver 40', etc). Additionally, the microphone signal is applied to a signal conditioning chain 70b-70d, before being used as a control input to the controller sub-system 70e.

The signal conditioning chain typically will include a low-pass filter 70b to isolate the substantially low frequency pressure pulse that is produced when the head- or earphone body 20' is displaced by manual input. The filtered signal is detected by the block 70c before being operated upon by the pulse shaper 70d. The resulting signals are interpreted by logic in the controller sub-system 70e, which generates local control commands or commands for remote systems to be transmitted over the interface 80'. The details of this logic are without the scope of the present invention (an analogous logic layer exists in those prior art devices in which the signals arise from mechanical switches or their equivalent).

The signal conditioning chain 70b-70d must be designed so as to differentiate between signals associated with pressure changes evoked by manual commands and pressure changes associated with audio program material reproduced by the head- or earphone. This conveniently may be achieved by exploiting significant differences in amplitude and frequency between the two signal types; pressure pulses arising from manual deformations of the compliant suspension 30' will tend to be larger in amplitude and lower in frequency than program audio components (which is why 70b is shown as a low-pass filter). In more sophisticated embodiments, program audio components arising from the action of the receiver 40' can be actively cancelled from the output of microphone 50' as part of the signal conditioning chain.

Figure 4 shows earphone apparatus 10" in which movement of the personal audio system inertial frame 20" caused by touch is transduced (i.e. a mechanical embodiment). The output from the accelerometer 100" is "split" within the electronics 70". One accelerometer signal component continues to be used for its principal purpose of tracking head position. Additionally, the accelerometer signal is applied to a signal conditioning chain 70b'-70d', before being used as a control input to the controller sub-system 70e'.

The signal conditioning chain typically will include a high-pass filter 70b' to isolate the substantially high frequency acceleration that is produced when the head- or earphone body 20" is displaced by manual input (here "high frequency" is defined relative to the much lower frequency elements that represent head motion). The filtered signal is detected by the block 70c' before being operated upon by the pulse shaper 70d'. The resulting signals are interpreted by logic in the controller sub-system 70e', which generates local control commands or commands for remote systems to be transmitted over the interface 80". In order to track head position in three dimensions, three mutually orthogonal signals will usually be present. These individual "channels" conveniently may be exploited in differentiating between various allowed manual control inputs; taps in orthogonal dimensions can be interpreted (by the control logic) to signal different commands.

Systems can achieve higher levels of robust detection of manual inputs from the wearer by exploiting both acoustical and mechanical means simultaneously (where the mechanical axis concerned is that which coincides with the axis of maximal compression/extension of the compliance 30" and, thereby, maximal change in the volume 60".

The present invention allows a personal audio platform (such as a headphone or earphone) to be sensitive to manual command/control inputs from the wearer. However, this sensitivity is provided not by the inclusion of switches or other sensors provided just to service the manual control interface. Rather, sensors already present in the apparatus are exploited to derive sensitivity to manual inputs. Such sensors are available within contemporary active personal audio systems - especially those incorporating active noise reducing technologies - which is the scope of the present invention. Additionally, the provision of enhanced functionality for personal audio platforms in the future will entail the incorporation of a richer set of transducers, many of which may be able to serve dual function in facilitating the manual control interface according to the invention disclosed in this specification.

Claims

Claims:

1. Earphone apparatus comprising:

a transducer used in processing an audio signal, generating an acoustic output to a user, or tracking movement of a head-mounted part of the earphone apparatus;

wherein the transducer is further configured to provide to a signal processor an input signal for altering operation of the earphone apparatus or a device connected to the earphone apparatus, the input signal being generated in response to a predetermined user interaction with the earphone apparatus detectable by the transducer.

2. Earphone apparatus according to claim 1, wherein the predetermined user interaction with the earphone apparatus detected by the transducer is movement of a part of the earphone apparatus relative to the user.

3. Earphone apparatus according to claim 2, wherein movement of the part of the earphone apparatus relative to the user is achieved by virtue of a compliant element of the earphone apparatus.

4. Earphone apparatus according to any of claims 1-3, wherein the transducer is an electro-acoustic transducer and the predetermined user interaction with the earphone apparatus generates an acoustic signal.

5. Earphone apparatus according to claim 4, wherein the predetermined user interaction with the earphone apparatus may be movement of a part of the earphone apparatus relative to the user causing a change in pressure sensed by the electro-acoustic transducer.

6. Earphone apparatus according to claim 5, wherein the transducer is a sensing microphone configured to sense sound present in the auditory canal of the user's ear or an electro-acoustic driver acoustically coupled to the auditory canal of the user's ear, and the predetermined user interaction with the earphone apparatus is movement of the earphone apparatus relative to the user causing a change in volume of air in communication with the sensing microphone or electro-acoustic driver.

7. Earphone apparatus according to claim 4 or claim 5, wherein the acoustic signal is generated by a user interaction generating an acoustic wave.

8. Earphone apparatus according to claim 7, wherein the acoustic signal is generated by a user causing transient vibration of a part of the earphone apparatus.

9. Earphone apparatus according to claim 8, wherein the earphone apparatus is provided with outer surface features or internal features configured to enhance generation of the acoustic signal.

10. Earphone apparatus according to any of claims 1-3, wherein the transducer is an accelerometer used to track movement of a head-mounted part of the earphone apparatus.

11. Earphone apparatus according to any of the preceding claims wherein the signal processor is configured to monitor for combinations of input signals.

12. Earphone apparatus according to claim 11, wherein the signal processor is configured to act on the received input signals only if the combination of input signals is received within a predetermined time period.

13. Earphone apparatus according to any of the preceding claims, wherein the signal processor is configured to filter signals received from the transducer.

14. Earphone apparatus according to any of the preceding claims, wherein the signal processor is configured to perform feature extraction or pattern recognition.

15. Earphone apparatus according to any of the preceding claims, wherein the signal processor is configured to subtract from a received signal estimates of signal components arising from normal operation of the earphone apparatus.

16. Earphone apparatus according to claim 15, wherein the signal processor is configured to subtract from a received signal estimates of signal components arising from movement of the user's head.

17. Earphone apparatus according to claim 15, wherein the signal processor is configured to subtract from a received signal estimates of signal components arising from external noise.

18. Apparatus according to any of the preceding claims, wherein the earphone apparatus forms part of a hearing-aid.

19. Apparatus according to any of claims 1-17, wherein the earphone apparatus forms part of a headset including a microphone for a user to speak into.