FEEDBACK ELIMINATION IN A HEARING AID

Abstract

A hearing aid includes an input unit, an output unit, a signal processing unit connected to the input unit and output unit, where the input unit, the signal processing unit and the output unit form part of a forward path of the hearing aid, where the signal processing unit is configured to apply a forward gain to the at least one electric input signal or a signal originating therefrom. The hearing aid further includes a feedback reduction unit configured to reduce risk of howl due to acoustic, electrical, and/or mechanical feedback of an external feedback path from the output unit to the input unit. The feedback reduction unit is configured to modulate the forward gain in time to provide that the forward gain exhibits an increased or unchanged forward gain in one or more first time periods and a reduced forward gain in one or more second time periods.

Claims

1. Hearing aid (HA) configured to be worn by a hearing aid user at or in an ear of the hearing aid user or to be fully or partially implanted in the head at an ear of a hearing aid user, the hearing aid comprising an input unit configured to receive an input sound signal from an environment of a hearing aid user and to provide at least one electric input signal (IN) representing said input sound signal, an output unit configured to provide at least one set of stimuli perceivable as sound to the hearing aid user based on a processed version of said at least one electric input signal (IN), a signal processing unit (SPU) connected to the said input unit and output unit, where the input unit, the signal processing unit (SPU) and the output unit are forming part of a forward path of the hearing aid, where the signal processing unit (SPU) being configured to apply a forward gain to the at least one electric input signal or a signal originating therefrom, where the hearing aid (HA) further comprising a feedback reduction unit (FBRU) configured to reducing a risk of howl due to acoustic, electrical, and/or mechanical feedback of an external feedback path (FBP) from the output unit to the input unit of said hearing aid (HA), where the feedback reduction unit (FBRU) is configured to modulate said forward gain in time to provide that the forward gain exhibits an increased or unchanged forward gain A.sub.H in one or more first time periods T.sub.H and a reduced forward gain A.sub.L in one or more second time periods T.sub.L, and where the hearing aid (HA) further comprises a filler signal unit (FU) configured to generate a filler signal (FS), and to provide said filler signal (FS) to the resulting signal (OUT) of the feedback reduction unit (FBRU) in said one or more second time periods T.sub.L, corresponding to said reduced forward gain A.sub.L.

2. Hearing aid (HA) according to claim 1, wherein one or more of said increased or unchanged forward gain A.sub.H, reduced forward gain A.sub.L, one or more first time periods T.sub.H, and one or more second time periods T.sub.L is/are based according to a predetermined or adaptively determined criterion.

3. Hearing aid (HA) according to claim 2, wherein said forward path and an external feedback path (FBP) of the hearing aid defining a loop path exhibiting a roundtrip loop delay, and wherein said criterion comprises that said one or more first time periods T.sub.H and/or said one or more second time periods T.sub.L time period are based in dependence of said, possibly averaged, roundtrip loop delay of said forward path and external feedback path (FBP).

4. Hearing aid (HA) according to claim 1, wherein the filler signal unit (FU) is configured to provide a filler signal (FS) of equal numerical size or smaller size than the difference in forward gain between successively modulated increased or unchanged forward gain A.sub.H and reduced forward gain A.sub.L.

5. Hearing aid (HA) according to claim 1, wherein generating a filler signal comprises providing an additional electric input signal representing sound to said resulting signal (OUT) of the feedback reduction unit (FBRU).

6. Hearing aid (HA) according to claim 1, wherein the filler signal (FS) is based on a noise signal.

7. Hearing aid (HA) according to claim 1, wherein the filler signal (FS) is based on the input sound signal from the environment of a hearing aid user.

8. Hearing aid (HA) according to claim 1, wherein the filler signal unit (FU) being configured to estimate the size, duration and/or periodicity of the filler signal (FS), based on the resulting signal (OUT) from the feedback reduction unit (FBRU).

9. Hearing aid (HA) according to claim 1, wherein the filler signal unit (FU) being configured to estimate the size, duration and/or periodicity of the filler signal (FS) based on advanced signal processing and/or a neural network.

10. Hearing aid (HA) according to claim 1, wherein the hearing aid further comprises a feedback cancellation unit.

11. Hearing aid (HA) according to claim 1, wherein the hearing aid further comprises an analysis filter bank and a synthesis filter banks, and where the filler signal unit (FU) is configured to generate a band split filler signal (FS-F), and to provide said filler signal (FS-F) to the resulting band split signal (RES-F) of the feedback reduction unit (FBRU).

12. A hearing system comprising left and right hearing aids according to claim 1, where the left and right hearing aids are configured to be worn in or at left and right ears, respectively, of said hearing aid user, and/or to be fully or partially implanted in the head at left and right ears, respectively, of the hearing aid user, and being configured to establish a wired or wireless connection between them allowing data, e.g. audio data, to be exchanged between them, optionally via an auxiliary device.

13. Method of processing an electric signal representing sound, the method comprising: receiving an input sound signal from an environment of a hearing aid user and providing at least one electric input signal (IN) representing said input sound signal, by an input unit, providing at least one set of stimuli perceivable as sound to the hearing aid user based on a processed version of said at least one electric input signal, by an output unit, applying a forward gain to the at least one electric input signal or a signal originating therefrom, by a signal processing unit (SPU) connected to the said input unit and output unit, where the input unit, the signal processing unit (SPU) and the output unit forming part of a forward path of the hearing aid, applying a forward gain to the at least one electric input signal or a signal originating therefrom and providing a processed version of said at least one electric input signal, by the signal processing unit (SPU), where the hearing aid (HA) further comprising a feedback reduction unit (FBRU) for reducing a risk of howl due to acoustic, electrical, or mechanical feedback of an external feedback path (FBP) from the output unit to the input unit of said hearing aid, modulating said forward gain in time, to provide that the forward gain exhibits an increased or unchanged forward gain AH in one or more first time periods TH and a reduced forward gain AL in one or more second time periods TL, by the feedback reduction unit (FBRU), and generating a filler signal (FS), and providing said filler signal (FS) to the resulting signal (OUT) of the feedback reduction unit in said one or more second time periods TL, corresponding to said reduced forward gain AL, by a filler signal unit (FU) of the hearing aid (HA).

14. A computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of claim 13.

15. A data processing system comprising a processor and program code means for causing the processor to perform at least some of the steps of the method of claim 13.

16. Hearing aid (HA) according to claim 2, wherein the filler signal unit (FU) is configured to provide a filler signal (FS) of equal numerical size or smaller size than the difference in forward gain between successively modulated increased or unchanged forward gain A.sub.H and reduced forward gain A.sub.L.

17. Hearing aid (HA) according to claim 3, wherein the filler signal unit (FU) is configured to provide a filler signal (FS) of equal numerical size or smaller size than the difference in forward gain between successively modulated increased or unchanged forward gain A.sub.H and reduced forward gain A.sub.L.

18. Hearing aid (HA) according to claim 2, wherein generating a filler signal comprises providing an additional electric input signal representing sound to said resulting signal (OUT) of the feedback reduction unit (FBRU).

19. Hearing aid (HA) according to claim 3, wherein generating a filler signal comprises providing an additional electric input signal representing sound to said resulting signal (OUT) of the feedback reduction unit (FBRU).

20. Hearing aid (HA) according to claim 4, wherein generating a filler signal comprises providing an additional electric input signal representing sound to said resulting signal (OUT) of the feedback reduction unit (FBRU).

Description

BRIEF DESCRIPTION OF DRAWINGS

[0185] The aspects of the disclosure may be best understood from the following detailed description taken in conjunction with the accompanying figures. The figures are schematic and simplified for clarity, and they just show details to improve the understanding of the claims, while other details are left out. Throughout, the same reference numerals are used for identical or corresponding parts. The individual features of each aspect may each be combined with any or all features of the other aspects. These and other aspects, features and/or technical effect will be apparent from and elucidated with reference to the illustrations described hereinafter in which:

[0186] FIG. 1A shows an exemplary hearing aid comprising a feedback cancellation system according to prior art.

[0187] FIG. 1B shows an exemplary hearing aid comprising a feedback cancellation system according to prior art and, in particular, comprising an adaptive filter.

[0188] FIG. 2 shows an exemplary hearing aid comprising a feedback reduction unit and a filler signal unit.

[0189] FIG. 3 shows an exemplary round-trip loop delay in the hearing aid.

[0190] FIG. 4A shows an exemplary modulated forward gain pattern.

[0191] FIG. 4B shows an exemplary temporal filler signal pattern.

[0192] FIG. 5 shows an exemplary hearing aid comprising a feedback cancellation unit and a feedback reduction unit.

[0193] FIG. 6A shows an exemplary hearing aid comprising analysis and synthesis filter banks for analysing different frequency bands separately.

[0194] FIG. 6B shows an exemplary hearing aid comprising analysis and synthesis filter banks for analysing different frequency bands separately, and additionally including a feedback cancellation unit.

[0195] The figures are schematic and simplified for clarity, and they just show details which are essential to the understanding of the disclosure, while other details are left out. Throughout, the same reference signs are used for identical or corresponding parts.

[0196] Further scope of applicability of the present disclosure will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the disclosure, are given by way of illustration only. Other embodiments may become apparent to those skilled in the art from the following detailed description.

DETAILED DESCRIPTION OF EMBODIMENTS

[0197] The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. Several aspects of the apparatus and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). Depending upon particular application, design constraints or other reasons, these elements may be implemented using electronic hardware, computer program, or any combination thereof.

[0198] FIG. 1A shows an exemplary hearing aid comprising a feedback cancellation system according to prior art.

[0199] The hearing aid (HA) may be configured to be worn by a hearing aid user at or in an ear of the hearing aid user or to be fully or partially implanted in the head at an ear of a hearing aid user. The hearing aid (HA) may be configured to compensate for a hearing loss of the hearing aid user.

[0200] In FIG. 1A, the hearing aid is shown to comprise a forward path for processing at least one electric input signal representing an input sound signal from an environment of the hearing aid user.

[0201] The forward path may comprise an input unit, shown as an input transducer (IT) (e.g. microphones), for picking up sound (‘Acoustic input’) from the environment of the hearing aid (HA) and providing respective at least one electric input signal (IN). The forward path may further comprise a signal processing unit (SPU) for processing the at least one electric input signal (IN) or one or more signals originating therefrom and providing one or more processed signals (OUT) based thereon. The forward path may further comprise an output unit, shown as an output transducer (OT) (e.g. a loudspeaker or a vibrator) for generating stimuli perceivable by the user as sound (‘Acoustic output’) based on the one or more processed signals (OUT).

[0202] The hearing aid (HA) may further comprise a feedback cancellation unit (FBC) for feedback control (e.g. attenuation or removal), wherein said feedback cancellation unit (FBC) may comprise a feedback estimation unit (FBE) configured to estimate a current feedback path (FBP) from the output transducer (OT) to the input transducer (IT) and providing a feedback path estimate signal (fbp) indicative thereof.

[0203] The hearing aid (HA) may further comprise a combination unit (here a summation (subtraction) unit, ‘+’) for combining the electric input signal (IN) or a signal derived therefrom and the feedback path estimate signal (fbp) estimated by said feedback cancellation unit (FBC) (here subtracting the feedback path estimate signal (fbp) from the electric input signal (IN)), to provide a resulting feedback corrected signal (fbc).

[0204] The feedback estimation unit (FBE) may estimate the current feedback path (FBP) based on the one or more processed signals (OUT) from the signal processing unit (SPU) and the resulting feedback corrected signal (fbc) from the combination unit (‘+’).

[0205] FIG. 1B shows an exemplary hearing aid comprising a feedback cancellation system according to prior art and, in particular, comprising an adaptive filter.

[0206] In FIG. 1B, it is shown that the hearing aid (HA) may comprise a feedback reduction unit (FBRU) in the forward path of the hearing aid. The forward path shown in FIG. 1B comprises the same functional units as shown in FIG. 1A, and additionally the feedback reduction unit (FBRU).

[0207] The feedback reduction unit (FBRU) is illustrated to be located between the signal processing unit (SPU) and the output transducer (OT). The feedback reduction unit (FBRU) may alternatively be located elsewhere in the forward path, e.g. between the input transducer (IT) (of the input unit) and the signal processing unit (SPU), or it may form part of the signal processing unit (SPU).

[0208] The input transducer (IT) may provide a digitized electric input signal (IN) representative of the Acoustic input. This signal is fed to the signal processing unit (SPU) providing an enhanced signal (ENHS) (after application of a requested (e.g. frequency and/or level dependent) forward gain to the electric input signal (IN)). The enhanced signal ENHS is fed to the feedback reduction unit (FBRU) providing a resulting signal OUT, which is fed to the output transducer (OT) (of the output unit) for conversion to an Acoustic output.

[0209] The feedback reduction unit (FBRU) may be configured to modulate the requested forward gain in time. Preferably, the requested forward gain applied to the signal processing unit (SPU) is modulated to provide that a resulting forward gain exhibits an increased or unchanged forward gain A.sub.H in one or more first time period T.sub.H and a reduced forward gain A.sub.L in one or more second time period T.sub.L, (cf. e.g. FIG. 4A).

[0210] The hearing aid (HA) of FIG. 1B may additionally comprise a feedback cancellation unit (FBC) comprising a feedback estimation unit (FBE) for providing a feedback path estimate signal (fbp) (of the estimated current feedback path (FBP) from the output transducer to the input transducer) and a combination unit (‘+’), (as also shown in FIG. 1A). The input signal to the adaptive filter (Algorithm and Filter units) of the FBE is preferably the resulting signal (OUT) of the feedback reduction unit (FBRU).

[0211] FIG. 2 shows an exemplary hearing aid comprising a feedback reduction unit and a filler signal unit.

[0212] In FIG. 2, it is shown that the hearing aid (HA) may comprise a feedback reduction unit (FBRU) in the forward path. The feedback reduction unit (FBRU) may be configured to produce a spectral-temporal modulation (STM) on the enhanced signal (ENHS) from the signal processing unit (SPU) according to a specific modulated/alternating increased-reduced forward gain pattern and to provide a resulting signal (RES).

[0213] The hearing aid (HA) may additionally comprise a filler signal unit (FU) configured to generate said a filler signal (FS). The filler signal unit (FU) may be configured to provide said filler signal (FS) to the resulting signal (RES) (from the feedback reduction unit (FBRU)) by a combination unit (‘+’) in a second time period T.sub.L, corresponding to a reduced resulting forward gain A.sub.L. The filler signal unit (FU) may generate a filler signal (FS) that is independent or dependent on the STM pattern.

[0214] FIG. 4A shows an exemplary modulated forward gain pattern.

[0215] FIG. 4A shows an example of a repetitive time (Time) dependent forward gain (Gain) pattern that may be applied to a signal of the forward path by a feedback reduction unit of a hearing aid. The exemplary modulated gain pattern may comprise a rectangular pulse shaped pattern where a second time period T.sub.L may be larger than a first time period T.sub.H.

[0216] The modulated gain shown in FIG. 4A (bold solid line) consists of repeated periods of increased (high) forward gain A.sub.H and reduced (low) forward gain A.sub.L with durations of TH and TL, respectively, relative to a predetermined required forward gain, equated to the gain value 1 (dotted line), as applied by a signal processing unit of a hearing aid.

[0217] The first and second time periods (TH and TL, respectively) may be determined in dependence of the round-trip loop delay (cf. e.g. FIG. 3 showing an exemplary round-trip loop delay in the hearing aid). The repeated periods of increased (high) forward gain A.sub.H and reduced (low) forward gain A.sub.L may be of similar size of vary/adaptively adjusted after each round-trip loop.

[0218] Additionally, or alternatively, the durations of T.sub.H and T.sub.L may be in a similar order of magnitude as (e.g. approximately equal to) the loop delay T.sub.loop (see FIG. 3) in the acoustic feedback system. T.sub.H and T.sub.L may be adjusted to obtain different performance. Both time periods may be close to the loop delay T.sub.loop . As an example, when the loop delay T.sub.loop=10 ms, the duration of T.sub.L may be chosen to be T.sub.L=5 ms, 9 ms, 10 ms, 11 ms, . . . or 30 ms etc, and the duration of T.sub.H may be chosen to be T.sub.H=30 ms, 11 ms, 10 ms, 9 ms, 5 ms etc. The first (T.sub.H) and second time periods (T.sub.L) may alternatively be equal (T.sub.H=T.sub.L). The forward gain pattern is shown as a rectangular pattern in FIG. 4A, but may alternatively take any other appropriate form, e.g. involving a smooth transition from decreased forward gain (A.sub.L) to increased forward gain (A.sub.H) and/or from increased forward gain (A.sub.H) to decreased forward gain (A.sub.L), or e.g. a gradual transition.

[0219] FIG. 4B shows an exemplary temporal filler signal pattern.

[0220] FIG. 4B shows schematically an example of a filler signal generated by the filler signal unit in dependence of the modulated forward gain pattern (STM pattern) as illustrated in FIG. 4A.

[0221] The filler signal may have an opposite behavior as of the modulated forward gain applied by the feedback reduction unit on the enhanced signal from the signal processing unit. In other words, when the filler signal is added to the resulting signal (by a combination unit), it may fill (partly or completely) the gaps produced by the (STM) modulation on the resulting signal of the feedback reduction unit and therefore allow for an output acoustic signal which sounds smoother in the ear of the hearing aid user.

[0222] The increased forward gain (AH) and decreased forward gain (AL) in the modulated forward gain pattern may be of around 1 and around 0, respectively. In this case, the filler signal may be considered to be added in an “open-loop” manner (i.e., the filler signal will not travel around the feedback loop “forever”). Alternatively, in case the increased forward gain (AH) and decreased forward gain (AL) are between 0 and 1, the filler signal may be added not-completely in an “open loop”, but with a proper negative loop gain (<0 dB). Thereby, the filler signal will not build up to create feedback, and additionally it can actually improve the adaptive estimation of the feedback path, as the added filler signal further decorrelates the signals for the adaptive estimation of feedback path.

[0223] The filler signal unit may be configured to provide a filler signal of equal numerical size/value (AFS) as the difference in forward gain between successively modulated increased forward gain A.sub.H and reduced forward gain A.sub.L. Alternatively, or additionally, the filler signal unit may be configured to provide a size/value (ΔFS) of the filler signal that is smaller than the difference in forward gain between successively modulated increased forward gain A.sub.H and reduced forward gain A.sub.L.

[0224] The filler signal unit may be configured to adaptively adjusting (e.g. adaptively determining) the size/value (AFS) of the filler signal in the plurality of second time period T.sub.L corresponding to the reduced gain A.sub.L.

[0225] The durations of the filler signal may correspond to the duration to the durations of the one or more second time periods T.sub.L of reduced forward gain A.sub.L. For example, durations of the filler signal may be equal to the durations of the one or more second time periods T.sub.L of reduced forward gain A.sub.L.

[0226] The durations of the filler signal may be in a similar order of magnitude as (e.g. approximately equal to) the loop delay T.sub.loop (see FIG. 3) in the acoustic feedback system. For example, when the loop delay T.sub.loop=10 ms, the durations of the filler signal may be chosen to be 5 ms, 9 ms, 10 ms, 11 ms, . . . or 30 ms etc.

[0227] The filler signal is shown as a rectangular pattern in FIG. 4B, but may alternatively take any other appropriate form, e.g. involving a smooth transition from decreased filler signal to increased filler signal and/or from increased filler signal to decreased filler signal, or e.g. a gradual transition.

[0228] FIG. 5 shows an exemplary hearing aid comprising a feedback cancellation unit and a feedback reduction unit.

[0229] FIG. 5 shows an exemplary hearing aid (HA) comprising a feedback reduction unit (FBRU) in the forward path of the hearing aid (as also shown in FIG. 2) as well as a feedback cancellation unit comprising a feedback estimation unit (FBE) for estimating the acoustic feedback path (FBP) from the output transducer (OT) to the input transducer (IT). The forward path may further comprise a combination unit (‘+’) (as also shown in FIG. 1B).

[0230] The input transducer (IT) (of the input unit) may further comprise a microphone (MIC) for converting an input sound (Acoustic input) to an analogue electric input signal and an analogue-to-digital (AD) converter to digitize the analogue electric input signal from the microphone (MIC) with a predefined sampling rate, e.g. 20 kHz, and provide a digitized electric input signal (IN) to the forward path.

[0231] The output transducer (OT) (of the output unit) may comprise a digital-to-analogue (DA) converter to convert a digital signal (OUT) (e.g. of the combination unit (‘+’)) to an analogue electric output signal. Further, the output transducer (OT) may comprise a loudspeaker (SP) configured to present the analogue electric output signal to a hearing aid user as an output sound (Acoustic output).

[0232] As also shown in FIG. 2, the hearing aid (HA) may comprise a filler signal unit (FU) configured to generate a filler signal (FS) and provide it to the modulated resulting signal (RES) of the feedback reduction unit (FBRU) by the combination unit (‘+’). The filler signal (FS) may be provided in one or more second time periods T.sub.L, corresponding to one or more reduced forward gains A.sub.L.

[0233] FIG. 6A shows an exemplary hearing aid comprising analysis and synthesis filter banks for analysing different frequency bands separately.

[0234] FIG. 6A shows an exemplary hearing aid (HA) comprising a forward path comprising an input transducer (IT) (of an input unit) providing an electric input signal (IN) in the time domain, and an analysis filter bank (FBA) providing the electric input signal IN in a number of frequency bands (e.g. 4, 8, or 64) as band split electric input signal (IN-F).

[0235] The forward path may further comprise a signal processing unit (SPU) connected to the analysis filter bank (FBA). The signal processing unit may be configured to apply a requested forward gain to the band split electric input signal (IN-F) and to provide an enhanced band split signal (ENHS-F).

[0236] The forward path may further comprise a feedback reduction unit (FBRU) for applying a gain modulation to the enhanced band split signal (ENHS-F) and providing a resulting band split signal (RES-F) with a forward gain exhibiting an increased or unchanged forward gain (A.sub.H) in one or more first time periods (T.sub.H) and a reduced forward gain (A.sub.L) in one or more second time periods (T.sub.L) for each of the number of frequency bands. Thereby, a resulting band split signal (RES-F) is provided with a reduced risk of creating feedback (i.e. reducing a risk of creating howl due to acoustic or mechanical feedback from the output to the input transducer).

[0237] The forward path may additionally include a filler signal unit (FU) configured to generate a band split filler signal (FS-F), and to provide said filler signal (FS-F) to the resulting band split signal (RES-F) (i.e. to each of the number of frequency bands) of the forward path by a combination unit (‘+’). Thereby, an output band split signal (OUT-F) is generated.

[0238] The forward path may further comprise a synthesis filter bank (FBS) for generating a resulting time domain signal (OUT) from the resulting band split signal (RES-F). The synthesis filter bank (FBS) may be connected to an output transducer (OT) (e.g. a loudspeaker or a vibrator of an output unit) for converting the resulting time domain signal (OUT) to an acoustic or vibrational stimulus for presentation to a hearing aid user (U).

[0239] FIG. 6B shows an exemplary hearing aid comprising analysis and synthesis filter banks for analysing different frequency bands separately, and additionally including a feedback cancellation unit.

[0240] In FIG. 6B, an exemplary hearing aid (HA) as shown in FIG. 6A further comprising a conventional feedback cancellation system (FBC) is shown. The feedback cancellation system (FBC) may comprise a feedback estimation unit (FBE) and a combination unit (‘+’), where the combination unit (‘+’) may be located in the forward path of the hearing aid (HA). The forward path may further comprise a feedback reduction unit (FBRU) and the filler signal unit (FU) as described in connection with FIG. 6A.

[0241] The feedback estimation unit (FBE) may provide a feedback path estimate signal (fbp), which may be subtracted from the electric input signal (IN) by the combination unit (‘+’). The resulting feedback corrected signal (fbc) may be fed to the signal processing unit (SPU) and to the feedback estimation unit (FBE).

[0242] The exemplary hearing aid shown in FIG. 6B is similar to the exemplary hearing aid of FIG. 5 (which may operate in the time domain) apart from the fact that, in FIG. 6B, a part of the forward path (comprising the signal processing unit (SPU), the feedback reduction unit (FBRU), and the filler signal unit (FU)) may be operating in the (time-) frequency domain. In FIG. 6B, the feedback cancellation system (including feedback estimation unit (FBE) and combination unit (‘+’)) may be operated in the time domain. It may alternatively be operated fully or partially in the (time-) frequency domain.

[0243] It is intended that the structural features of the devices described above, either in the detailed description and/or in the claims, may be combined with steps of the method, when appropriately substituted by a corresponding process.

[0244] As used, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (i.e. to have the meaning “at least one”), unless expressly stated otherwise. It will be further understood that the terms “includes,” “comprises,” “including,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will also be understood that when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element but an intervening element may also be present, unless expressly stated otherwise. Furthermore, “connected” or “coupled” as used herein may include wirelessly connected or coupled. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items.

[0245] The steps of any disclosed method are not limited to the exact order stated herein, unless expressly stated otherwise.

[0246] It should be appreciated that reference throughout this specification to “one embodiment” or “an embodiment” or “an aspect” or features included as “may” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure. Furthermore, the particular features, structures or characteristics may be combined as suitable in one or more embodiments of the disclosure. The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects.

[0247] The claims are not intended to be limited to the aspects shown herein but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more.