Patent Application
20240323617
This application claims the priority, under 35 U.S.C. § 119, of German Patent Application DE 10 2023 202 422.5, filed Mar. 20, 2023; the prior application is herewith incorporated by reference in its entirety.
The invention relates to a method for directional signal processing for a binaural hearing system having a first hearing instrument and a second hearing instrument. A first directional signal is generated on the basis of first input signals of the first hearing instrument by means of directional signal processing, and a second directional signal is generated on the basis of second input signals by means of directional signal processing, and wherein an output signal of the hearing system is generated by means of a superposition of the first directional signal of the first hearing instrument with the second directional signal of the second hearing instrument.
A hearing instrument generally refers to an electronic device that supports the hearing capacity of a person wearing the hearing instrument (hereafter referred to as the “wearer” or “user”). In particular, the invention relates to hearing instruments which are designed to completely or partially compensate for a hearing loss of a hearing-impaired user. Such an instrument is also known as a hearing aid. In addition, there are hearing instruments that protect or improve the hearing capacity of normal-hearing users, for example to enable improved speech comprehension in complex listening situations, or in the form of communication devices (e.g., headsets or similar, possibly with earbud-shaped headphones).
Hearing instruments in general, and hearing aids in particular, are usually designed to be worn on the head and here in particular, in or on an ear of the user. In the operation of the hearing instrument, one or more (acousto-electric) input transducers capture an ambient sound and convert this ambient sound into a corresponding electrical input signal, the voltage fluctuations of which typically carry information on the vibrations of the air pressure induced in the air by the ambient sound. In a signal processing device (a signal processor), the or each input signal is processed (i.e., modified with regard to its sound information) in order in particular to support the hearing capacity of the user, particularly preferably to compensate for a hearing loss of the user. The signal processing device outputs a correspondingly processed audio signal as an output signal to an output transducer (e.g., a loudspeaker), which converts the output signal into an output sound signal. The output sound signal can consist of airborne sound, which is emitted into the user's auditory canal. For example, the output sound signal can also be emitted into the bones of the user's skull.
In particular, individual sound sources can be emphasized by directional signal processing (directional microphony) of multiple input signals, or noise sources can be decreased or even completely masked. Especially in more complex listening situations with multiple sound sources, only one or a few of which may be considered useful signal sources, the wearer can benefit from a possible improvement in the signal-to-noise ratio (SNR). However, a problem can arise when a noise source is located in the same spatial direction as a useful signal source.
It is accordingly an object of the invention to provide a signal processing method which overcomes the above-mentioned and other disadvantages of the heretofore-known devices and methods of this general type and which provides for a method for directional signal processing for a hearing instrument or a hearing system having a hearing instrument, which allows a targeted emphasis of a useful signal source in the simultaneous presence of noise sources in the same spatial direction.
With the above and other objects in view there is provided, in accordance with the invention, a method for directional signal processing in a binaural hearing system having a first hearing instrument and a second hearing instrument, the method comprising:
In other words, the above and other objects are achieved, in accordance with the invention, by a method for directional signal processing for a binaural hearing system having a first hearing instrument and a second hearing instrument, wherein a plurality of input transducers of the first hearing instrument generates a corresponding plurality of first input signals from a sound signal of the environment, wherein a plurality of second input transducers of the second hearing instrument generates a corresponding plurality of second input signals from the sound signal of the environment, and wherein a direction with respect to a preferred direction of the binaural hearing system and a distance with respect to a reference point of the binaural hearing system are predetermined, and a focal point is thereby predetermined.
According to the method, it is provided that a first directional signal is generated from the first input signals by means of directional signal processing in such a way that a direction of maximum sensitivity, starting from the first hearing instrument, forms a first yaw angle with the said preferred direction, and a second directional signal is generated from the second input signals by means of directional signal processing, in such a way that a direction of maximum sensitivity, starting from the second hearing instrument, forms a second yaw angle with the said preferred direction, wherein the first yaw angle and the second yaw angle are adjusted via the directional signal processing of the first and second input signals respectively, in such a way that a superposition of the first directional signal with the second directional signal has a maximum sensitivity in an overlap region that includes the predetermined focal point, and wherein an output signal of the binaural hearing system is generated on the basis of the said superposition. Advantageous embodiments, which are inventive in themselves, are the subject matter of the dependent claims and the following description.
A hearing instrument, in this case, generally refers to any device which is designed to generate a sound signal from an electrical signal-which can also be provided by an internal signal of the device—and to deliver said sound signal to the hearing system of a wearer of this device, in particular to a headphone (e.g., as an “earplug”), a headset, a pair of data glasses with a loudspeaker, etc. A hearing instrument, however, also includes a hearing device in the narrower sense, that is, a device for treating a hearing impairment of the wearer, in which an input signal generated from an ambient signal by means of a microphone is processed into an output signal and amplified, in particular in a frequency band-dependent manner, and an output sound signal generated from the output signal by means of a loudspeaker or similar device is suitable for compensating for the hearing impairment of the wearer, at least partially, in particular in a user-specific manner.
The term “binaural hearing system” refers to a system comprising two hearing instruments in the above sense, each individual one of which serves to treat one ear of the wearer (i.e., the left or the right ear) and is worn by the wearer on or in the respective ear when operated as intended, so that both ears of the wearer are treated by one hearing instrument each.
An input transducer in this case includes any device which is configured to generate a corresponding electrical signal from an acoustic signal. In particular, the generation of the first or second input signal by the respective input transducer can also include a pre-processing stage, e.g., in the form of a linear pre-amplification and/or an A/D conversion. The input signal generated accordingly is formed in particular by an electrical signal, the current and/or voltage fluctuations of which essentially represent the sound pressure fluctuations of the air.
In each of the two hearing instruments, therefore, from the ambient sound, which preferably comprises at least one useful signal of a corresponding useful signal source, a plurality of first and second input signals is generated by corresponding first and second input transducers, wherein the specific number does not necessarily have to be identical for both hearing instruments. However, the same number of input signals is preferably generated in both hearing instruments.
A distance is now defined with respect to a reference point of the binaural hearing system, as well as a direction with respect to a preferred direction of the binaural hearing system. This defines a focal point, which is thus located in the specified direction at the specified distance with respect to the preferred direction and starting from the reference point. Preferably, this specifies the direction and distance for a sound source, particularly preferably for a useful signal source.
In particular, the said reference point of the binaural hearing system is determined on the basis of a mid-point between the first hearing instrument and the second hearing instrument when the system is worn as intended, and/or the said preferred direction of the binaural hearing system is determined on the basis of a frontal direction of the wearer when wearing the hearing instruments of the hearing system as intended. The term ‘wearing as intended’ includes in particular the arrangement of the hearing instruments in or on the respective ear as intended for operation, matching their anatomy. The reference point and/or the preferred direction can be determined directly as the mid-point or the frontal direction, or as a function of these, for example via a relative (angular) deviation that should not be exceeded.
The concept of directional signal processing comprises in particular a mapping of the signals to be processed by the directional signal processing onto at least one signal resulting from the directional signal processing, which has a non-trivial directional characteristic, i.e., has different sensitivities in at least two different spatial directions as a result of the directional signal processing. In particular, the directional signal processing can be achieved by means of a possibly multi-stage (i.e., cascaded), time-delayed superposition of the signals to be processed, wherein optionally, by means of a primary time-delayed superposition one or more intermediate signals are first generated, which in turn (optionally time-delayed again) can be superimposed in order to generate the resulting signal.
The first input signals are then processed by means of such directional signal processing into the first directional signal as a resulting signal, in such a way that the direction of maximum sensitivity (in particular the maximum of the directional characteristic) of the first directional signal is pivoted relative to the predetermined preferred direction of the binaural hearing system by a first yaw angle. This can be implemented in particular via the parameters of the directional processing (e.g., time constants and/or weights of the superposition). The same applies to the generation of the second directional signal from the second input signals with respect to the second yaw angle.
Via parameters of the respective directional signal processing, the first and the second yaw angle of the first and second directional signal should be adjusted in such a way that the two directional signals, idealized as beam-shaped and represented by their yaw angles (or corresponding rays emanating from the respective hearing instrument, which are at the corresponding yaw angle to the preferred direction), crossing as closely as possible at the focal point or at least in a delimitable region in its immediate vicinity (such a region can be defined, for example, by limits for relative angular deviations of the yaw angle and/or for relative deviations of the maximum sensitivity).
A superposition of the first directional signal thus generated with the correspondingly generated second directional signal now has an overlap region in which the two maximum sensitivities of the directional signals are amplified (for example in comparison to a sensitivity of this superposition averaged over the entire space). Depending on the specification of the preferred direction and the distance (above all in comparison to the distance between the hearing instruments), this overlap region can cover not only a specific spatial direction (the preferred direction), but can also cover a minimum and/or maximum radial extent with respect to the reference point in this spatial direction (or an angular region that can be delimited as described above), depending on its specific design. This means in particular that the maximum sensitivity of the signal resulting from the said superposition is located in the relevant spatial direction at a specific distance, and with increasing (and in particular also decreasing) distance in the spatial direction (at a constant angular width, or spread) the sensitivity decreases, wherein the spatial direction and the distance are preferably selected in such a way that they correspond to the focal point.
In this way, the superposition can generate a signal, which can emphasize sound sources in a specifically predetermined and in particular not only angular, but also radially delimitable spatial region, and in doing so de-emphasize sound sources located in the same spatial direction, but further away (i.e., outside the radial boundary).
The signal resulting from the said superposition of the first directional signal with the second directional signal is then used for the generation of an output signal, which is preferably output by an output transducer of the hearing system to the hearing system of the wearer. An output transducer can include any device which is designed and configured to convert an electrical signal into a corresponding sound signal, wherein voltage and/or current fluctuations in the electrical signal are converted into corresponding amplitude fluctuations of the sound signal, thus in particular a loudspeaker, a so-called balanced metal case receiver, but also a bone-conducting headset.
In particular, for the above-described method the respectively required input and/or directional signals as well as information on the predetermined direction and the predetermined distance between the two hearing instruments can be transmitted. The preferred method involves transmitting only the contra-lateral directional signal from the respective other hearing instrument at the level of the signals (e.g., the second directional signal from the second hearing instrument to the first hearing instrument).
Preferably, the first yaw angle and the second yaw angle are adjusted on the basis of the predetermined distance and the predetermined direction and on the basis of the distance of the first hearing instrument from the second hearing instrument, in particular via parameters of the respective directional signal processing, in such a way that an intersection point of the associated angular lines (or rays) of the two yaw angles emanating from the respective hearing instrument does not exceed a predetermined maximum distance from the predetermined focal point. The yaw angles can be adjusted in particular such that the intersection point ideally exactly coincides with the focal point. However, it may be advantageous, e.g., if a sound source to be emphasized is moving, if the intersection point of the directional signals, idealized as beam-shaped, is not placed exactly at the focal point at all times, but rather allows a predefined, maximum deviation.
It proves advantageous if the first directional signal is generated from the first input signals in such a way that it has a first angular width (i.e., angular aperture, angular spread) around the first yaw angle, within which the sensitivity does not fall below a predetermined minimum value, and/or if the second directional signal is generated from the second input signals in such a way that it has a second angular width about the second yaw angle, within which the sensitivity does not fall below a specified minimum value. This ensures that the overlap region does not fall below a specific radial and angular dimension. This is particularly advantageous for a safe “catching” of the focal point with the overlap region.
Conveniently, the first angular width and/or the second angular width is defined on the basis of the smallest distance of the overlap region from the reference point and/or on the basis of the largest distance of a spatial point of the overlap region from the reference point. This means in particular that a radial extent is specified for the overlap region, which is bounded by the smallest distance of the overlap region to the reference point, the largest distance of a spatial point of the overlap region to the reference point, and the first or second angular width, preferably via parameters of the respective directional signal processing, are adjusted on the basis of this radial extent.
Preferably, the first directional signal is generated on the basis of a time-delayed superposition of the first input signals, and in the process the first yaw angle and optionally the first angular width is adjusted using at least one time constant and/or at least one weighting factor of said time-delayed superposition. Accordingly, the second directional signal is generated on the basis of a time-delayed superposition of the second input signals, and in the process the second yaw angle or the second angular width is adjusted using at least one time constant and/or at least one weighting factor of said time-delayed superposition. As linear signal processing processes, time-delayed superpositions have the advantage of simple implementation and easily understandable control of the respective angular sizes.
It also proves advantageous in this case if as the plurality of first input signals a front first input signal and a rear first input signal are each generated by a corresponding frontal and rear first input transducer, and/or, as the plurality of second input signals, a front second input signal and a rear second input signal are each generated by a corresponding frontal and rear second input transducer. While more than two input signals per hearing instrument can also be used for the method, on the one hand, the use of only two input signals per hearing instrument is already sufficient, and moreover, sufficient for an output signal of usable quality for the emphasis of a sound signal at the focal point. In addition, hearing instruments to be worn on or in the ear are often subject to considerable restrictions in the space available for individual components. When the hearing instrument in question is worn as intended, the respective frontal or rear input transducer is preferably arranged correspondingly further forward or further back in the hearing instrument with regard to the preferred direction (wherein, in addition, a longitudinal displacement, i.e., cranial or caudal, for both input transducers of the same hearing instrument is possible).
In an advantageous embodiment, a head-related transfer function (HRTF) for the first hearing instrument or for the second hearing instrument is used for adjusting the first yaw angle and/or the second yaw angle. An HRTF describes the spatial filtering effect of the shadowing effects of the head and outer ear (pinna and concha) as a function of angle for sound propagating to the auditory canal. Such shadowing effects can influence the direction of maximum sensitivity for the first or second directional signal, and thus distort it with respect to the yaw angle to be adjusted. Taking these effects into account by means of HRTFs thus allows any such distortion to be corrected.
It also proves advantageous if the direction with respect to the preferred direction of the binaural hearing system is specified as a direction of a sound source in the environment with respect to the preferred direction, and if the distance with respect to the reference point of the binaural hearing system is specified as a distance of said sound source to the reference point. Although the method can in principle emphasize the overlap region regardless of whether a useful signal source is arranged at the focal point (or nearby), in the case of a sound source for the specification of the direction and distance, it is particularly advantageous due to the possibility of a selective emphasis of the sound source. The specification can be provided in particular statically, or also dependent on external information (e.g., using data glasses or the like).
However, it is particularly advantageous for the specification if, based on an analysis of at least some of the first input signals and/or the second input signals, the direction of the sound source in the environment with respect to the said preferred direction and/or the distance of the sound source with respect to said reference point is determined to obtain the specification. This allows the emphasis of the sound source to be performed dynamically as a function of its position, and in particular a change in a position of a specific sound source can be taken into account for updating the focal point.
For this purpose, a change in the direction and/or the distance of the sound source is preferably determined based on said analysis of at least some of the first input signals and/or the second input signals, wherein the specification of the focal point is updated accordingly and wherein the first yaw angle and the second yaw angle are re-adjusted accordingly.
In a further advantageous embodiment, a plurality of first analysis directional signals is generated based on the first input signals by means of directional signal processing, in such a way that each of the first analysis directional signals has a minimum sensitivity in a different minimum direction with respect to the preferred direction in each case, and a first source direction of the sound source with respect to the said preferred direction is determined on the basis of the first analysis directional signals, starting from the first hearing instrument, wherein a plurality of second analysis directional signals is generated based on the second input signals by means of directional signal processing, in such a way that each of the second analysis directional signals has a minimum sensitivity in a different minimum direction with respect to the preferred direction in each case, and a second source direction of the sound source with respect to the said preferred direction is determined on the basis of the second analysis directional signals, starting from the second hearing instrument. Furthermore, on the basis of the first source direction, the second source direction and the distance between the first hearing instrument and the second hearing instrument, the distance of the said sound source with respect to the reference point of the binaural hearing system and the direction of the sound source with respect to the preferred direction are determined. The analysis thus described by means of the said analysis directional signals is preferably carried out in each case in an analysis path of the hearing system, in particular of the respective hearing instrument, and generation of an output signal of the hearing system is preferably carried out in a processing path parallel to the analysis path. The analysis directional signals thus “scan” the environment in each case, in order to determine for each hearing instrument, in each case with respect to the preferred direction, the source direction of a particular sound source, preferably a specific speaker.
For this purpose, speech recognition is preferably carried out in each of the first and/or second directional signals based on spectral and/or temporal features, wherein the first or second source direction is determined based on speech components detected in the first and/or second directional signals, and a first speaker is localized as the sound source.
In particular, a specific first input signal of a specific first or second input transducer can be used as the first or second reference signal, wherein speech recognition is carried out in the first or second reference signal, and wherein the first or second source direction is determined on the basis of differences of speech components, in this case detected in the first or second reference signal, with respect to the speech components detected in the first or second reference signals respectively.
The invention further specifies a binaural hearing system having a first hearing instrument and a second hearing instrument, wherein the binaural hearing system is configured to carry out the above-described method. The binaural hearing system according to the invention shares the advantages of the method according to the invention. The advantages specified for the method and for its extensions can be transferred mutatis mutandis to the binaural hearing system. For carrying out the method, the binaural hearing system is equipped in particular with the corresponding input transducers and additionally with means for directional signal processing and means for transmitting respectively required input and/or directional signals as well as angle and/or distance information between the two hearing instruments.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as being embodied in a method for directional signal processing for a binaural hearing system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
Equivalent parts and dimensions are provided with identical reference signs and symbols throughout the figures.
Referring now to the figures of the drawing in detail and first, in particular, to
The directional characteristic 14 has its maximum sensitivity in the direction a and around it, which is shown in
The first hearing instrument HI1 has a frontal first input transducer Mv1 and a rear first input transducer Mh1, which respectively generate a front first input signal Ev1 and a rear first input signal Eh1 from the sound signal 10 of the environment. The second hearing instrument HI2 has a frontal first input transducer Mv2 and a rear second input transducer Mh2, which each generate a front second input signal Ev2 and a rear second input signal Eh2 from the sound signal 10 of the environment. The said input transducers Mv1, Mh1, Mv2, Mh2 in the present case are provided by corresponding omni-directional microphones.
In the first hearing instrument HI1, a first directional signal R1 is then formed by a directional signal processor 22 based on the front and rear first input signal Ev1, Eh1 and based on a specification of a direction a and a distance D to be described below, which define a focal point F. For this purpose, a time-delayed superposition is formed from the said input signals Ev1, Eh1 in the present exemplary embodiment, and in particular a first HRTF (referred to in
The second directional signal R2 is then transmitted from the second hearing instrument HI2 to the first hearing instrument HI1. For this purpose, both hearing instruments HI1 and HI2 are equipped with appropriate communication devices, such as, for example, Bluetooth and/or NFC-enabled antennas.
In the first hearing instrument HI1, a first superposition U1 is then formed from the first directional signal R1 and the second directional signal R2 (here, U1 designates both the process of the first superposition and the signal resulting from the first superposition). From the signal of the first superposition U1, a first output signal A1 is generated in the first hearing instrument, which is reproduced by a first output transducer L1 of the first hearing instrument HI1 as an output sound signal (not shown) and supplied to the hearing system of the wearer 1. The first output transducer L1 can be formed in particular as a loudspeaker. However, the first output transducer L1 can also be formed as a bone-conduction headset or similar. The signal of the first superposition U1 may be subject to further signal processing steps (such as frequency band-dependent amplification and/or compression) for generating the first output signal A1.
In a similar manner, a second superposition (not shown) is formed in the second hearing instrument HI2 from the first directional signal R1 and the second directional signal R2, from which, optionally by additional signal processing (see above), a second output signal for a second output transducer of the second hearing instrument HI2 is generated.
In a manner to be described below, by means of the binaural hearing system 20 according to
As an explanation of this, the conversation situation according to
For this, the frontal direction 8 forms a preferred direction 24 when the hearing system is worn as intended. Likewise, when worn as intended (in particular in the anatomically correct arrangement of the two hearing instruments HI1, HI2 on the respective ears), a reference point 26 of the binaural hearing system 20 is defined by the mid-point 25 between the two hearing instruments HI1, HI2. The reference point 26 is located in the head 6 of the wearer 1, and is used in the following geometric considerations and corresponding calculations.
For the selective enhancement of the interlocutor D, both its distance D from the reference point 26 as well as its direction a (i.e., the direction of its position with respect to the preferred direction 24) are specified in a manner not yet described in detail. This defines the focal point F as the target point for the signal processing. For the first directional signal R1, a direction of maximum sensitivity and the second directional signal R2 (represented in
For the said alignment, a first yaw angle γ1, which indicates the direction of maximum sensitivity of the first directional signal 1, is aligned from the first hearing instrument HI1 to the focal point (see associated arrow), and a second yaw angle γ2, which indicates the direction of maximum sensitivity of the second directional signal 1, is aligned from the second hearing instrument HI2 to the focal point. This can be carried out in each case via parameters of the directional signal processors 22 of the binaural hearing system 20 according to
In
As already described with reference to
This can be achieved in particular by forming a simple sum of the form
For the specification of the distance D and the direction a, based on the frontal and rear first and second input signals Ev1, Eh1, Ev2, Eh2 (and, optionally, taking into account HRTF1 and HRTF2 respectively; not shown), a plurality of analysis directional signals RA1a-z, RA2a-z is formed in the first hearing instrument HI1 and in the second hearing instrument HI2, each having their minimum sensitivity in different angular directions (“minimum directions”). These analysis directional signals RA1a-z, RA2a-z “scan”, in each case via the variation of their minimum directions, the space surrounding the associated hearing instrument HI1, HI2 for sound sources, wherein a sound source present in a minimum direction of a particular analysis directional signal is attenuated by the same.
To identify a sound source, the analysis directional signals RA1a-z, RA2a-z are compared locally with the front first and second input signal Ev1, Ev2 respectively of the relevant hearing instrument HI1, HI2 as a respective reference signal (alternatively, the rear first or second input signal Eh1, Eh2 can also be used in each case as such a local reference signal). On the basis of the differences in the respective signal power, the presence of a sound source in the minimum direction of the relevant analysis directional signal can then be inferred. In particular, for detecting whether a sound source is a useful signal source, it can be assumed in this case that such a useful signal source is given by a speaker, and then speech recognition (not shown in
Although the invention has been illustrated and described in greater detail by means of the preferred exemplary embodiment, the invention is not restricted by the examples disclosed and other variations can be derived therefrom by the person skilled in the art without departing from the scope of protection of the invention.
The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 202 422.5 | Mar 2023 | DE | national |
