EP3275211B1 - Method for operating an electro-acoustic system and electro-acoustic system - Google Patents

Description

The invention relates to a method for operating an electroacoustic system in which an electroacoustic device for at least partially occluding an auditory canal is arranged at least partially on an ear. The invention also relates to an electroacoustic system which is operated according to such a method.

Such a method and such an electroacoustic system are known from US Pat US 2014/0321657 A1 known. An incoming acoustic signal can then be modified, taking into account the acoustic properties of the auditory canal in an area between the device at least partially occluding the auditory canal and the eardrum.

A transparent hearing aid is out of the document WO 2014/070825 A1 known. The hearing system has a signal processing device. Filters are used to correct and modify the transmission characteristics in order to achieve acoustic transparency.

The document US 2006/0002574 A1 describes a canal hearing device that is implemented with a functionality that offers acoustic transparency as well as an energy-saving function so that a user can wear the device during the sleep phase or during inactivity without significant loss of the normal unsupported reaction in the ear canal. The transparent mode has an in-situ acoustic transmission function that compensates for the insertion loss caused by the presence of a hearing aid in the ear canal.

It is known to use electroacoustic systems and / or an electroacoustic device that at least partially or completely occlude an ear and / or an auditory canal, fill in, lock and / or lock for example in the field of entertainment electronics and / or hearing aids. The disadvantage here is that the occlusion of the auditory canal causes a change in the perception of ambient noise. This changed perception of, in particular natural, ambient noises can have an attenuation, a spectral modification, a change in the color tone, a change in the sound spectrum and / or a change in spatial perception. It is particularly disadvantageous that ambient noises are not perceived and / or as unnatural when the auditory canal is at least partially occluded by means of the electroacoustic device. This can endanger the person using the electroacoustic device, in particular in traffic. In addition, wearing and / or using the electroacoustic device can be perceived as uncomfortable.

It is the object of the invention to further develop a method and an electroacoustic system of the type mentioned at the beginning in such a way that a disruptive and / or undesired change in the perception of ambient noise when using an electroacoustic device that at least partially occludes the ear canal reduces or prevents it and / or is at least partially offset.

und nachfolgend das geänderte eingehende Signal mittels des zweiten Korrekturfilters (B) zum Ausfiltern von Übertragungseffekten im Bereich von der Vorrichtung (10) bis zum Trommelfell aufgrund der mindestens teilweisen Okklusion des Gehörganges mittels der Vorrichtung (10) modifiziert wird.The object on which the invention is based is achieved by means of a method and an electroacoustic system of the type mentioned at the beginning, with a signal processing device being used to process a signal arriving at the device, and in which at least one correction unit of the signal processing device is used to modify the signal arriving at the device is used, and by means of the at least one correction unit, an outgoing signal from the device is generated to achieve acoustic transparency, in which a received signal is generated based on the outgoing signal on the eardrum, which corresponds to a free-ear received signal on the eardrum with a free ear canal is adapted without the device, wherein the at least one correction unit has a first correction filter (A) and a second correction filter (B), and the first correction filter (A) of the at least one correction unit has the second correction turfilter (B) is connected upstream of the at least one correction unit, wherein the incoming signal is first modified by means of the first correction filter (A) to achieve the acoustic transparency, a total pressure (P _tot ) for determining the first correction filter (A) of the at least one correction unit. an external acoustic signal within the auditory canal, which is at least partially occluded with the device, taking into account the first correction filter (A _{) is equated with an expected target pressure (P T, E} ), the first correction filter (A) taking into account a device assigned by means of one and an inner sound receiver facing the eardrum of the ear, measured throughput pressure (P _HT ) is determined with the following equation: $$\mathrm{A.}=\frac{{\mathrm{P.}}_{T,\mathrm{E.}}-{\mathrm{P.}}_{\mathit{HT}}}{{\mathrm{P.}}_{\mathit{dead}}-{\mathrm{P.}}_{\mathit{HT}}}$$

and subsequently the changed incoming signal is modified by means of the second correction filter (B) to filter out transmission effects in the area from the device (10) to the eardrum due to the at least partial occlusion of the auditory canal by means of the device (10).

The advantage here is that ambient noises can be perceived in sufficient quality despite an at least partially occluded ear canal. In particular, the method and / or the electroacoustic system make it possible to monitor, control and / or manipulate the received signals, preferably a frequency response, on the eardrum. This allows the electroacoustic system to be operated in an acoustic transparency mode. The perception of ambient noise by a person using the electroacoustic system is preferably not, at most slightly and / or to a non-disruptive extent, or is not disturbed or changed due to the acoustic transparency. The person using the electroacoustic system preferably experiences a sound perception, in particular approximately as if with a free auditory canal. Thus, the method and / or the electroacoustic system enables a more pleasant, in particular natural, perception of ambient noises in the case of a partially and / or completely occluded ear canal. Here, the electroacoustic system can enable a large number of additional functions, for example in connection with entertainment electronics, with hearing protection, with a hearing aid and / or with a communication device, in particular a mobile phone and / or a smartphone. In particular, a hearing aid can additionally be provided, preferably if required. The received signal generated on the eardrum can be amplified and / or attenuated in comparison to the signal arriving at the device.

In the context of the present application, the acoustic transparency is preferably designed as a perceptual acoustic transparency. In particular, perceptual and / or acoustic transparency means that there is no audible difference to a free-ear signal or a free-ear reception signal. In this way, perceptual and / or acoustic transparency can be achieved without an absolute physical match between the received signal generated on the eardrum and a free-ear received signal in the case of a free auditory canal without having to reach the device. It is preferably sufficient if a person using the device has the perception that the received signal generated with the device corresponds in perceptual terms to the free-ear received signal in the case of a free auditory canal without the device.

The correction unit has a first correction filter and a second correction filter. The first correction filter of the signal processing device is used to achieve the acoustic transparency. The second correction filter of the signal processing device is used to modify the Device outgoing, in particular acoustic, signal used. By means of the second correction filter, the acoustic properties of a section of the auditory canal from the device to an eardrum of the ear are taken into account. According to a further embodiment, the first correction filter and / or the second correction filter can be designed as, in particular digital, electrical circuits. The correction unit, the first correction filter and / or the second correction filter can have at least one analog-to-digital converter and / or at least one digital-to-analog converter.

The first correction filter of the correction unit is connected upstream of the second correction filter of the correction unit. The incoming signal is first modified by means of the first correction filter to achieve acoustic transparency. The changed incoming and / or incoming signal is then modified by means of the second correction filter to filter out transmission effects in the area from the device to the eardrum due to the at least partial occlusion of the auditory canal by means of the device. By means of the outgoing, in particular acoustic, signal from the device, a received signal is generated which corresponds to the free-ear received signal with a free auditory canal without the device. A disruptive influence of the device at least partially occluding the auditory canal on the perception of ambient noises can thus be reduced and / or compensated for. To achieve acoustic transparency due to the outgoing signal in the area of the auditory canal section from the device to the eardrum, a received signal is generated which is adapted to and / or corresponds to a free-ear received signal in this area of the auditory canal section with a free auditory canal without the device .

According to a further development, the incoming, in particular acoustic, signal is fed to the signal processing device as an incoming electrical signal by means of an external sound receiver assigned to the device and directed away from the eardrum and outward. At least one additional external acoustic and / or electrical signal is preferably fed to the signal processing device, in particular by means of an additional external sound receiver and / or a direct line connection to an additional external signal source. In particular, the outer sound receiver and / or the additional outer sound receiver are each designed as a microphone. The additional external acoustic and / or electrical signal can also be modified by means of the correction unit.

In particular, a negative feedback loop can be implemented by means of the electroacoustic system. The external sound receiver and the additional external sound receiver are preferably used to implement the negative feedback loop.

According to a further embodiment, a calibration is carried out before the electroacoustic system is used. In particular, a first correction filter and / or a second correction filter is determined as part of the calibration. The calibration preferably takes place after each insertion of the device for at least partially occluding the auditory canal. The calibration is particularly preferably carried out by means of an external sound source and / or a calibration control. Alternatively, a start calibration for determining the first correction filter and the second correction filter, in particular by means of an external sound source, can first be carried out. After the initial calibration has taken place and the device for at least partially occluding the auditory canal has been reinserted, only a single correction filter, in particular the first correction filter or the second correction filter, is recalibrated as part of a partial calibration. Headphones, which are placed on an auricle with an inserted electroacoustic device, can serve as an external sound source for calibration. The use of a signal that hits the ear from the outside is particularly advantageous for detecting the spatial resolution of an incoming signal. The calibration control can be in the device, an earpiece, a computer and / or a smartphone. In particular, the calibration control has a processor. The calibration controller can be connected to the electroacoustic device by means of a cable, a wireless connection, a near field communication and / or Bluetooth.

An individual calibration is preferably carried out for the respective person using the device and / or after each insertion of the device into the auditory canal. In particular, a calibration and / or setting of the first and / or second correction filter is carried out during ongoing operation. This enables readjustment to be carried out. A readjustment is preferably carried out if at least one predetermined triggering parameter is given. For example, readjustment can take place at specified times or at specified time intervals. Alternatively or additionally, a readjustment can be initialized if at least one predetermined and monitored trigger parameter is reached, undershot or exceeded.

In particular, the correction unit, the first correction filter and / or the second correction filter is recalibrated and / or adjusted during operation. A continuous and / or discontinuous calibration, in particular in connection with a start and / or initial calibration, can thus take place.

A first correction filter of the correction unit is preferably determined on the basis of a first model and / or a second correction filter of the correction unit on the basis of a second model. The first model and / or the second model is preferably based on the Thévenin equivalent and / or the Norton equivalent. These models are tried and tested and enable a sufficiently precise estimate of the relevant parameters.

According to a further development, the total pressure P _{tot of} an external acoustic signal within the auditory canal, which is at least partially occluded with the device, is made up of two parts for determining a first correction filter A of the correction unit. A first part of the total pressure P _{tot is preferably a passage pressure P HT} measured by means of an internal sound receiver assigned to the device and facing an eardrum of the ear. The inner sound receiver can be designed as a microphone. In particular, the passage _{pressure P HT is} a sound pressure of an external acoustic signal after passage through the auditory canal at least partially occluded with the device. A second part of the total pressure P _{tot is preferably a pressure P EP} emitted by means of a sound generator assigned to the device and facing the eardrum. The sound generator can be designed as a loudspeaker and / or receiver. At least one further and / or additional sound generator can be provided. The at least one additional sound generator can be arranged at an end facing the eardrum or an end of the device facing away from the eardrum.

In the context of the present invention, a pressure is preferably to be understood as a pressure frequency. In particular, a pressure frequency response at a sound receiver and / or an eardrum results from a pressure frequency of a signal source, a noise source and / or a sound generator.

To determine a first correction filter A of the correction unit, a total pressure P _{tot of} an external acoustic signal within the auditory canal, which is at least partially occluded with the device, is equated _{with an expected target pressure P T, E, taking into account the first correction filter (A).} The first correction filter A is determined with the following equation, _{taking into account a through pressure P HT} measured by means of an internal sound receiver assigned to the device and facing an eardrum of the ear: $$\mathrm{A.}=\frac{{\mathrm{P.}}_{T,\mathrm{E.}}-{\mathrm{P.}}_{\mathit{HT}}}{{\mathrm{P.}}_{\mathit{dead}}-{\mathrm{P.}}_{\mathit{HT}}}$$

In particular, after an initial determination of a first correction filter A of the correction unit, in particular as part of a calibration, a fine adjustment of the first correction filter A is carried out. At least one predetermined calibration signal and / or a predetermined noise is preferably used. The calibration signal can be in the form of white noise. _{In particular, during the fine adjustment, a pressure P E} measured by means of an inner sound receiver assigned to the device and facing an eardrum of the ear is compared with a target pressure P _{T, E} at the position of the inner sound receiver. In this case, the first correction filter A can be _{iteratively adapted in the event of a deviation of the measured pressure P E} from the target pressure P _{T, E} until a predetermined convergence criterion is reached.

_{Preferably, to determine a first correction filter A of the correction unit, a pressure P E} measured by means of an inner sound receiver assigned to the device and facing an ear drum is equated with an expected target pressure P _{T, E} at the inner sound receiver, the expected target pressure P _{T, E} at the inner sound receiver is estimated as a pressure at the location of the inner sound receiver with a free ear canal without the device.

_{The target pressure P T, E} to be expected at the inner sound receiver with a free auditory canal can be estimated by means of an electroacoustic model, in particular with a Thevenin pressure source model and / or a source impedance model. The target pressure P _{T, E} to be expected at the inner sound receiver is preferably estimated by means of a source pressure Ps, an auditory canal impedance Z _L and a radiation impedance Z _RAD , in particular using the following equation: $${\mathrm{P.}}_{T,\mathrm{E.}}={\mathrm{P.}}_{\mathrm{S.}}\frac{Z_{\mathrm{L.}}}{Z_{\mathrm{L.}}+Z_{\mathit{WHEEL}}}$$

According to a further development: to determine a second correction filter B of the correction unit by means of an internal sound receiver assigned to the device and facing an eardrum of the ear, an estimation of the acoustic received signal is carried out on the eardrum. A pressure on the eardrum P _D is preferably estimated by means of a pressure P _E measured on the inner sound receiver using an electroacoustic model of the auditory canal.

A pressure at the eardrum P _D is preferably determined by means of a pressure P _E measured at the inner sound receiver and by means of the correction filter B using the following equation: $${\mathrm{P.}}_{\mathrm{D.}}={\mathrm{P.}}_{\mathrm{E.}}\mathrm{B.}$$

Thus, the second correction filter B can be determined with knowledge of the pressure at the eardrum P _{D and the pressure P E} measured at the inner sound receiver.

The electroacoustic system with the electroacoustic device for at least partially occluding an auditory canal has a signal processing device for processing a signal arriving at the device. In this case, the signal processing device has at least one correction unit for modifying the signal arriving at the device. Furthermore, the correction unit is used to provide and / or generate an outgoing signal from the device, which serves to achieve acoustic transparency, in which a received signal can be generated on the basis of the outgoing signal on the eardrum that corresponds to a free-ear received signal on the eardrum adapted to a free ear canal without the device is. The correction unit has a first correction filter and a second correction filter. The first correction filter (A) of the correction unit is connected upstream of the second correction filter (B) of the correction unit, the incoming signal first being modified by means of the first correction filter (A) to achieve acoustic transparency. To determine the first correction filter (A) of the correction unit, a total pressure (P _tot ) of an external acoustic signal within the auditory canal, which is at least partially occluded with the device, is equated _{with an expected target pressure (P T, E), taking into account the first correction filter (A)} , the first correction filter (A) being determined with the following equation, _{taking into account a throughput pressure (P HT} ) measured by means of an internal sound receiver assigned to the device and facing an eardrum of the ear: $$\mathrm{A.}=\frac{{\mathrm{P.}}_{T,\mathrm{E.}}-{\mathrm{P.}}_{\mathit{HT}}}{{\mathrm{P.}}_{\mathit{dead}}-{\mathrm{P.}}_{\mathit{HT}}}$$

The changed incoming signal is then modified by means of the second correction filter (B) to filter out transmission effects in the area from the device (10) to the eardrum due to the at least partial occlusion of the auditory canal by means of the device (10).

The use of a method according to the invention and / or an electroacoustic system according to the invention in connection with hearing protection, in-ear headphones and / or a hearing aid is particularly advantageous. The method according to the invention and / or the electroacoustic system can be used in connection with entertainment electronics and / or with a communication device, in particular a mobile phone and / or a smartphone. In particular, the method and / or the electroacoustic system is integrated in an existing system and / or an existing device, such as, for example, in a hearing aid, an in-ear headphone, an in-the-ear hearing aid , a hearing aid, a behind-the-ear device and / or a communication device. An external and / or additional, in particular acoustic, signal can be mixed with an ambient signal of an ambient noise. In particular, the mixing takes place after the first correction filter has been applied to the incoming signal and / or the ambient signal.

The signal processing device can be integrated in an in-the-ear device, a behind-the-ear device, a computer and / or a communication device, in particular in a mobile phone and / or smartphone. The inner sound receiver, the outer sound receiver and / or the sound generator are preferably connected by means of a line to an in-the-ear device, a behind-the-ear device, a computer and / or a communication device, in particular in a mobile phone and / or smartphone , connected.

The acoustic transparency can enable a perception of ambient noises that is at least largely familiar to a person and / or spatial hearing in the case of a partially occluded ear canal.

According to a further embodiment, the electroacoustic system, the correction unit, the first correction filter and / or the second correction filter are designed to attenuate and / or suppress sound radiation to the outside, in particular away from the person using the device and / or the eardrum.

The electroacoustic device can have a ventilation device. The ventilation device can be designed as a ventilation channel in order to enable pressure equalization in the case of a device inserted into an auditory canal. In this way, the wearing comfort can be further improved. The device and / or an earpiece can comprise an air-permeable material. An inner sound receiver, an outer sound receiver and / or a sound generator can be arranged at least partially or completely within the ventilation device.

Fig. 1

eine schematische Darstellung einer elektroakustischen Vorrichtung für ein erfindungsgemäßes elektroakustisches System,

Fig. 2

eine schematische Darstellung eines elektroakustisches Modells der elektroakustischen Vorrichtung gemäß Fig. 1,

Fig. 3

eine schematische Darstellung einer logischen Schaltung einer Signalverarbeitung mit der elektroakustischen Vorrichtung gemäß Fig. 1 während einer Kalibrierung, und

Fig. 4

eine schematische Darstellung einer logischen Schaltung einer Signalverarbeitungseinrichtung der elektroakustischen Vorrichtung gemäß Fig. 1.

The invention is explained in more detail below with reference to the figures. Show it:

Fig. 1

a schematic representation of an electroacoustic device for an electroacoustic system according to the invention,

Fig. 2

a schematic representation of an electroacoustic model of the electroacoustic device according to FIG Fig. 1 ,

Fig. 3

a schematic representation of a logic circuit of signal processing with the electroacoustic device according to FIG Fig. 1 during calibration, and

Fig. 4

a schematic representation of a logic circuit of a signal processing device of the electroacoustic device according to FIG Fig. 1 .

Figure 1 shows a schematic representation of an electroacoustic device 10 for an electroacoustic system 11 according to the invention. The device 10 has an ear piece 12. In this embodiment, the shape of the ear piece 12 is adapted to an individual auditory canal of a person not shown here. Alternatively, at least one outer coating of the earpiece 12 can be designed to be elastic, as a result of which at least a partial adaptation of the surface of the earpiece 12 to the shape of an auditory canal is made possible. The earpiece 12 can be arranged in an inner auricle shell and / or an auditory canal entrance. The ear canal is at least partially, that is to say partially or completely, occluded by means of the earpiece 12.

The device 10 has an external sound receiver 13. In this exemplary embodiment, the external sound receiver 13 is designed as an external microphone. When the earpiece 12 is inserted in an ear and / or an auditory canal, the outer sound receiver 13 is directed away from an eardrum not shown here. The outer sound receiver 13 is directed outwards to receive an incoming signal, namely acoustic ambient noise. Here, the outer sound receiver 13 is arranged, for example, in the surface of the earpiece 12. The location of the outer sound receiver 13 enables the incoming signal to be all spatial contains monaural information. By means of the external sound receiver 13, incoming acoustic signals are converted into electrical signals.

Furthermore, the device 10 has an internal sound receiver 14. In this exemplary embodiment, the internal sound receiver 14 is designed as an internal microphone. When the earpiece 12 is inserted in an ear and / or an auditory canal, the inner sound receiver 14 faces an eardrum, not shown in detail here. The inner sound receiver 14 is directed inwards to detect a sound field in an auditory canal section from the device 10 or the earpiece 12 to the eardrum. Here, the inner sound receiver 14 is arranged, for example, in the surface of the earpiece 12. By means of the inner sound receiver 14, incoming acoustic signals are converted into electrical signals.

The device 10 has a sound generator 15. The sound generator 15 is arranged in the area of the inner sound receiver 14. Furthermore, the sound generator 15 faces an eardrum (not shown in detail here) when the earpiece 12 is inserted in an ear and / or an auditory canal. Here the sound generator 15 is arranged, for example, on the surface of the earpiece 12. The sound generator 15 is directed inwards to emit the outgoing signal into the auditory canal section between the device 10 or the earpiece 12 and the eardrum. The sound generator 15 is designed to convert an electrical signal into an acoustic signal.

The device 10 has a signal processing device 16. The outer sound receiver 13, the inner sound receiver 14 and the sound transducer 15 are each connected to the signal processing device 16 by means of a line. The signal processing device 16 is integrated into the earpiece 12 in this exemplary embodiment. Alternatively, the signal processing device 16 can also be arranged outside the earpiece 12, for example in a housing for arrangement behind an ear or in an auricle. Here, the signal processing device 16 is designed, for example, as a digital signal processing device 16. The signal processing device 16 has analog-to-digital converters and digital-to-analog converters which are connected to electroacoustic sound transducers, in particular to the outer sound receiver 13, the inner sound receiver 14 and the sound transducer 15. or corrections are carried out with respect to an incoming signal at the external sound receiver 13 and an outgoing signal from the sound generator 15.

The signal processing device 16 has a correction unit 17. By means of the correction unit 17, an on the device 10 or the external sound receiver 13 incoming signal is corrected and / or modified in order to generate a signal outgoing from the device 10 or from the sound generator 15. The correction unit 17 has a first correction filter A and a second correction filter B.

In this exemplary embodiment, the signal processing device 16 is connected to an additional external signal source 18 by means of a line. By means of the additional signal source 18, an additional external, in particular acoustic, signal can be fed to the signal processing device 16. The additional signal source can be designed as entertainment electronics, a music source and / or a communication device.

The device 10 or the earpiece 12 has a ventilation device 19. In this exemplary embodiment, the ventilation device 19 is designed as a ventilation channel. The ventilation device 19 enables a pressure equalization with a device 10 inserted into an auditory canal. An air volume of an auditory canal section between the earpiece 12 and the eardrum is connected to the environment outside the auditory canal or the ear by means of the ventilation device 19.

With an auditory canal at least partially occluded by means of the device 10 or the earpiece 12, the inner sound receiver 14 enables an estimation of a received signal and / or an acoustic signal on the eardrum, in particular a frequency response on the eardrum due to any noise source. This estimation can be made by assuming the mechanical-acoustic properties of the device 10 in such a way that the frequency response at the position of the inner sound receiver 14 and the eardrum are the same. In this exemplary embodiment, the pressure on the eardrum is estimated by means of the pressure measured at the position of the inner sound receiver 14 using an electroacoustic model of the auditory canal P.

Figure 2 FIG. 11 shows a schematic representation of an electroacoustic model 20 of the electroacoustic device 10 according to FIG Fig. 1 . The device 10 or the earpiece 12 according to FIG Fig. 1 is modeled as a Norton and / or Thevenin equivalent electroacoustic velocity and / or pressure model, which is compared with the ear canal impedance as shown in FIG Figure 2 connected is.

The source parameters are applied to an electroacoustic circuit model that has a voltage source for pressure or a current source for speed, an internal source impedance, the ear canal as the two-port and the eardrum as the terminating impedance of the circuit. The source terms P _S for the pressure, Qs for the speed and Z _S for the impedance are by means of measurements the impulse responses induced by the sources when connected to various loads of known theoretical impedances. These are therefore assumed to be known and are part of the electroacoustic auditory canal model P, which is dependent on the individual design of the device 10. The abbreviation P _L in the Figure 2 stands for the load pressure and the abbreviation Z _L for the load impedance.

The load impedance Z _{L is determined by means of the pressure P E} measured at the position of the inner sound receiver 14 and using the electroacoustic circuit model according to FIG Fig. 2 determined using the following formula: $$Z_{\mathrm{L.}}=\frac{Z_{\mathrm{S.}}{\mathrm{P.}}_{\mathrm{E.}}}{{\mathrm{P.}}_{\mathrm{S.}}-{\mathrm{P.}}_{\mathrm{E.}}}$$

und/oder unter Verwendung der Quellenimpedanz Z_S gemäß $$U_E=\frac{P_S-P_E}{Z_S}$$

bestimmt.If the source impedance Z _S , the load impedance of the auditory canal Z _L , in particular in a region from the device 10 or the earpiece 12 to the eardrum, and the pressure P _E present inside the auditory canal and / or a pressure frequency response are known the particle speed U _E at the position of the inner sound receiver 14 using the load impedance Z _L according to FIG $$U_{\mathrm{E.}}=\frac{{\mathrm{P.}}_{\mathrm{E.}}}{Z_{\mathrm{L.}}}$$

and / or using the source impedance Z _S according to $$U_{\mathrm{E.}}=\frac{{\mathrm{P.}}_{\mathrm{S.}}-{\mathrm{P.}}_{\mathrm{E.}}}{Z_{\mathrm{S.}}}$$

certainly.

The relationship of a pressure at the eardrum P _D to the pressure P _E at the position of the inner sound receiver 14 is given according to the energy density-based estimation method, as it is described, for example, in the following document:
M. Hiipakka, M. Karjalainen and V. Pulkki, "Estimating pressure at eardrum with pressure-velocity measurements from ear canal entrance", Application of Signal Processing to Audio and Acoustics, 2009. WASPAA '09. IEEE Workshop on., 2009 .

The measured pressure P _E at the position of the inner sound receiver 1 and the estimated particle velocity U _E are used to obtain the following estimate: $${\mathrm{P.}}_{\mathrm{D.}}=\sqrt{{\left|{\mathrm{P.}}_{\mathrm{E.}}\right|}^2+{\left|U_{\mathrm{E.}}\mathit{\rho c}\right|}^2}$$

Here p is the air density and c is the speed of sound.

The ratio of P _E to P _D is transferred to the linear filter B, resulting in the following equation: $${\mathrm{P.}}_{\mathrm{D.}}={\mathrm{P.}}_{\mathrm{E.}}\mathrm{B.}$$

By means of the filter B, the acoustic properties of the auditory canal, in particular in an area between the device 10 which at least partially occludes the auditory canal and the end of the earpiece 12 facing the eardrum, are taken into account in the modification or correction by means of the signal processing device 16 or the correction unit 17 .

Figure 3 shows a schematic representation of a logic circuit 21 of a signal processing with the electroacoustic device 10 according to Fig. 1 during a calibration.

The electroacoustic system 11, the device 10 or the earpiece 12 can be calibrated in situ, that is to say with an at least partially occluded ear canal. The aim of the calibration is to obtain a predetermined pressure and / or a predetermined frequency response on the eardrum using a calibration routine. For this purpose, filter A is determined. By means of the filter A, an outgoing signal from the device 10 or the sound generator 15 can be generated by modifying the incoming signal, which signal generates a target pressure and / or a target frequency response at the position of the inner sound receiver 14.

Thus, the pressure P _E at the position of the inner sound receiver 14 corresponds to the target pressure P _{T, E} at the position of the inner sound receiver 14: $${\mathrm{P.}}_{\mathrm{E.}}={\mathrm{P.}}_{T,\mathrm{E.}}$$

The pressure P _E or the target pressure P _{T, E} at the position of the inner sound receiver 14 results on the basis of an ambient noise signal from a noise source 22. The noise source 22 is outside the ear and causes usual ambient noise.

As according to the Figure 3 the acoustic signal emanating from the noise source 22 is divided into two partial signals 23, 24 within the auditory canal and in the case of an auditory canal that is at least partially occluded by means of the device 10 or the earpiece 12.

The first partial signal 23 is a through signal. A pressure frequency response and / or a passage pressure P _HT , which is measured at the position of the inner sound receiver 14, is assigned to the first partial signal 23. The second sub-signal 24 is a device output signal. The second partial signal 24 is generated and emitted by the earpiece 12 in the direction of the eardrum by means of the sound generator 15. The second partial signal 24 results from the signal arriving at the external sound receiver 13, which is modified by means of filtering by means of the first filter A and the second filter B and is then output by means of the sound generator 15. An outgoing pressure frequency and / or an outgoing pressure P _{EP is} assigned to the second partial signal 24.

_{For calibration, the through pressure P HT} and the outgoing pressure P _{EP are} measured by means of the sound receivers 13, 14 using the noise source 22, which is designed as headphones in this exemplary embodiment, when the filters A and B are not used. However, since the outgoing pressure P _EP cannot be measured independently of the passage _{pressure P HT} , a total frequency response and / or a total pressure P _{tot is} introduced: $${\mathrm{P.}}_{\mathit{dead}}={\mathrm{P.}}_{\mathit{EP}}+{\mathrm{P.}}_{\mathit{HT}}$$

The total pressure P _tot is set equal _{to the target pressure P T, E} , taking into account the correction filter A: $${\mathrm{P.}}_{T,\mathrm{E.}}={\mathrm{P.}}_{\mathit{HT}}+{\mathrm{P.}}_{\mathit{EP}}\mathrm{A.}={\mathrm{P.}}_{\mathit{HT}}+\left({\mathrm{P.}}_{\mathit{dead}}-{\mathrm{P.}}_{\mathit{HT}}\right)\mathrm{A.}$$

Thus, after the first determination described above, a first correction filter A is calculated using the measured frequency responses and / or pressures P _{T, E} , P _HT and P _tot as follows: $$\mathrm{A.}=\frac{{\mathrm{P.}}_{T,\mathrm{E.}}-{\mathrm{P.}}_{\mathit{HT}}}{{\mathrm{P.}}_{\mathit{dead}}-{\mathrm{P.}}_{\mathit{HT}}}$$

This first correction filter A is determined in the course of an initial calibration.

A fine adjustment of the correction filter A can then be carried out. About the actual frequency response and / or the pressure P _E at the inner sound receiver 14 to adapt to the target pressure P _{T, E} , a predetermined calibration signal is used. In this exemplary embodiment, the calibration signal is designed as white noise. The calibration signal is emitted by the noise source 22. The frequency response and / or the pressure P _{E is} measured by means of the internal sound receiver 14. On the basis of a deviation of the measured pressure P _E from the target pressure P _{T, E} , the correction filter A is adapted accordingly. _{If the measured pressure P E} deviates from the target pressure P _{T, E, the} first correction filter A is iteratively adapted until a predetermined convergence criterion is reached.

To determine the correction filter A or to achieve the acoustic transparency, the target pressure P _{T, E} at the position of the inner sound receiver 14 must be known. Furthermore, the generated frequency response and / or the pressure P _D on the eardrum must be the same for a free auditory canal and an at least partially occluded auditory canal with an active and calibrated device 10. Accordingly, the pressure P _D on the eardrum is set equal to the target pressure P _{T, D on the eardrum:} $${\mathrm{P.}}_{\mathrm{D.}}={\mathrm{P.}}_{T,\mathrm{D.}}$$

A target model T is introduced in order to provide the frequency response and / or the pressure on the eardrum as an individual estimate for each person using the device 10.

In this case, however, the frequency response and / or the target pressure P _{T, D} on the eardrum is not determined or estimated. Instead, the target frequency response and / or the target pressure P _{T, E is} estimated at the position of the inner sound receiver 14 with a free auditory canal.

An electroacoustic circuit model is used for this, which has a Thevenin pressure _{source model P S} and a source impedance model Z _S. The source _{pressure P S} is estimated by means of the frequency response measured at the external sound receiver 13 and / or the pressure measured there when an incoming signal is generated by the noise source 22. The radiation of the source pressure P _S into the auditory canal in the case of a free auditory canal is estimated by means of the radiation impedance Z _RAD and the auditory canal _{impedance Z L.}

The individual auditory canal impedance Z _L , which is dependent on the respective person, is determined by means of the measurements and calculations mentioned above. However, no individual measurements and / or determinations for the radiation impedance Z _{RAD are} possible. Therefore, an estimated value is used that is is based on a theoretical model and measurements with test subjects, as described, for example, in the following document:
M. Hiipakka, T. Kinnari, and V. Pulkki; "Estimating head-related transfer functions of human subjects from pressure-velocity measurements," The Journal of the Acoustical Society of America, 2012 .

This results in the target frequency response and / or the target pressure P _{T, E} at the position of the inner sound receiver 14 with a free ear canal as follows: $${\mathrm{P.}}_{T,\mathrm{E.}}={\mathrm{P.}}_{\mathrm{S.}}\frac{Z_{\mathrm{L.}}}{Z_{\mathrm{L.}}+Z_{\mathit{WHEEL}}}$$

In this exemplary embodiment, the calibration described above for determining the first correction filter A and the second correction filter B is carried out after each insertion of the device 10 or the earpiece 12 into the ear or the auditory canal. In this way, changes due to a different position of the device 10 or of the earpiece 12 in the auditory canal or on the ear are taken into account. In this way, acoustic transparency with a particularly high quality can be achieved. After the calibration or during normal operation of the device 10 or the earpiece 12, the correction filters A and B remain unchanged according to this exemplary embodiment. Alternatively, adaptive tracking and / or recalibration of the correction filter A and / or B can take place, in particular during normal operation.

After the calibration, the first correction filter A is used to modify the incoming signal, as a result of which the outgoing signal or the outgoing pressure P _{EP is} modified. By means of the second correction filter B, information about the transmission path from the position of the inner sound receiver to the eardrum is taken into account when modifying the incoming signal at device 10 or when generating the outgoing signal.

Figure 4 shows a schematic representation of a logic circuit 25 with a signal processing device 16 of the electroacoustic device 10 according to FIG Fig. 1 .

During normal operation, an ambient noise is picked up as an incoming acoustic signal by the external sound receiver 13, converted into an incoming electrical signal and sent to the signal processing device 16. The signal processing device 16 corrects and modifies the signal by means of the two correction filters A and B in order to match the frequency response and / or the pressure on the eardrum to the frequency response and / or the pressure on the eardrum in one case adapt to the free ear canal. In this exemplary embodiment, due to the two correction filters A and B, the same frequency response and / or the same pressure is generated on the eardrum as with a free auditory canal.

Such acoustic transparency is made possible because the incoming signal at the external sound receiver 13 contains all directional information. In contrast, the transmission path from the inner auricle to the eardrum for both the free and the at least partially occluded ear canal is independent of the incoming signal direction or sound direction.

According to Fig. 1 and Fig. 4 becomes an to the ambient noise, for example from the noise source 22 according to FIG Fig. 3 , additional signal is supplied to an additional signal source 18 of the device 10. For example, the additional signal source 18 is designed as entertainment electronics and / or as an additional sound receiver for the device 10. Depending on the purpose and / or the type of signal source 18, the additional signal is used to transmit information and / or to supplement the signal arriving at device 10. The frequency response and / or the pressure on the eardrum due to the additional signal or the additional signal source 18 is modified in this exemplary embodiment by means of the previously determined correction filters A and / or B. As a result of a correction by means of the correction filter B, the additional signal is modified in such a way that undesired transmission effects of the auditory canal in an area between an end of the device 10 or the earpiece 12 facing the eardrum and the eardrum are weakened and / or avoided.

List of reference symbols:

10

electroacoustic device

11

electroacoustic system

12th

Earpiece

13th

external sound receiver

14th

inner sound receiver

15th

Sound generator

16

Signal processing device

17th

Correction unit

18th

additional signal source

19th

Ventilation device

20th

electroacoustic model

21

logic circuit

22nd

Source of noise

23

first partial signal

24

second partial signal

A.

first correction filter

B.

second correction filter

P.

Ear canal model

T

Target model

PS

Source print

QS

Source speed

ZS

Source impedance

ZL

Load or ear canal impedance

PL

Load pressure

PE

Pressure on the inner sound receiver

UE

Particle speed at the inner sound receiver

PD

Pressure on the eardrum

ρ

Airtightness

c

Speed of sound

PT, D

Target pressure on the eardrum

PT, E

Target pressure on the inner sound receiver

Ptot

Total pressure

PHT

Passage pressure at the inner silencer

PEP

outgoing pressure

ZRAD

Radiation impedance

Claims (13)

1. Method for operating an electroacoustic system (11), in which an electroacoustic device (10) is arranged to at least partially occlude an ear canal, at least partially on one ear, in which a signal processing device (16) is used to process an incoming signal to the electroacoustic device (10), and in which at least one correction unit (17) of the signal processing device (16) is used to modify the signal incoming to the device (10), and by means of the at least one correction unit (17) an outgoing signal from the device (10) is generated to achieve acoustic transparency, by which, on the basis of the outgoing signal, a received signal is generated on the eardrum which is adapted to correspond to a free-ear received signal at the eardrum in the case of a free ear canal without the device (10), wherein the at least one correction unit (17) possesses a first correction filter (A) and a second correction filter (B), and the first correction filter (A) of the at least one correction unit (17) is arranged upstream of the second correction filter (B) of the at least one correction unit (17), wherein the incoming signal is firstly modified by the first correction filter (A) to achieve acoustic transparency, wherein for the determination of the first correction filter (A) of the at least one correction unit (17) a total pressure (P_tot) of an outer acoustic signal within the ear canal at least partially occluded by the device (10) is equated by taking into account the first correction filter (A) with an expected target pressure (P_T,E), wherein the first correction filter (A), by taking into account a passageway pressure (P_HT) measured by means of the inner receiver (14) associated with the device (10) and facing the eardrum of the ear, is determined with the following equation: $$A=\frac{P_{T,E}-P_{\mathit{HT}}}{P_{\mathit{tot}}-P_{\mathit{HT}}}$$

   

   and then the modified incoming signal is modified by means of the second correction filter (B) to filter out transmission effects in the area from the device (10) to the ear drum on the basis of the at least partial occlusion of the ear canal by the device (10).
2. Method according to claim 1, characterised in that the incoming, especially acoustic signal is supplied as an incoming electrical signal from the signal processing device (16) by means of the outwardly facing outer receiver (13) associated with the device (10) and away from the eardrum, preferably at least one additional external acoustic and/or electrical signal is supplied from the signal processing device (16), in particular by means of an additional outer receiver and/or from a direct wire connection with an additional external signal source (18), particularly preferably the additional external acoustic and/or electrical signal is modified by means of the correction unit (17).
3. Method according to one of the preceding claims, characterised in that a calibration is carried out before using the electroacoustic system (11), in particular in the course of the calibration the first correction filter (A) and/or the second correction filter (B) is determined, the calibration is preferably carried out after each insertion of the device (10) for at least partially occluding the ear canal, and particularly preferably the calibration is carried out by means of an external sound source (22) and/or a calibration control unit.
4. Method according to one of the preceding claims, characterised in that the first correction filter (A) of the correction unit (17) is determined on the basis of a first model and/or the second correction filter (B) of the correction unit (17) is determined on the basis of a second model, preferably the first model and/or the second model is based on the Thevenin equivalent and/or on the Norton equivalent.
5. Method according to one of the preceding claims, characterised in that the total pressure (P_tot) of an external acoustic signal within the ear canal that is at least partially occluded by the device (10) is composed of two parts to determine the first correction filter (A) of the correction unit (17), preferably a first part of the total pressure (P_tot) is a passage pressure (P_HT) measured by means of an internal sound receiver (14) that is associated with the device (10) and is facing an eardrum of the ear, and/or a second part of the total pressure (P_tot) is an outgoing pressure (P_EP) provided by a sound generator (15) that is associated with the device (10) and is facing the eardrum.
6. Method according to one of the preceding claims, characterised in that after a first determination of the first correction filter (A) of the correction unit (17), in particular in the course of a calibration, a fine adjustment of the first correction filter (A) is carried out, preferably at least one predefined calibration signal and/or a predefined noise is used, in particular a pressure (P_E) measured by means of an internal sound receiver (14) that is associated with the device (10) and is facing an eardrum of the ear, is compared with a target pressure (P_T,E) during the fine adjustment, wherein the first correction filter (A), in the case of a deviation of the measured pressure (P_E) from the target pressure (P_T,E), is iteratively adapted until a predefined convergence criterion is achieved.
7. Method according to one of the preceding claims, characterised in that to determine the first correction filter (A) of the correction unit (17), a pressure (P_E) measured by means of an internal sound receiver (14) that is associated with the device (10) and is facing an eardrum of the ear, is compared with an expected target pressure (P_T,E) on the internal sound receiver (14), wherein the expected target pressure (P_T,E) on the internal sound receiver (14) is estimated as the pressure at the location of an internal sound receiver (14) for a free ear canal without the device (10).
8. Method according to claim 7, characterised in that the expected target pressure (P_T,E) on the internal sound receiver (14) is estimated by means of an electroacoustic model, in particular with a Thevenin-pressure source model and/or a source-impedance model, preferably the expected target pressure (P_T,E) on the internal sound receiver (14) is estimated by means of a source pressure (Ps), an ear canal impedance (Z_L) and a radiation impedance (Z_RAD), in particular with the following equation: $$P_{T,E}=P_S\frac{Z_L}{Z_L+Z_{\mathit{RAD}}}$$

   
9. Method according to one of the preceding claims, characterised in that an estimation of the acoustic received signal at the eardrum is carried out to determine the second correction filter (B) of the correction unit (17) by means of an internal sound receiver(14) that is associated with the device (10) and is facing an eardrum of the ear, preferably the pressure at the eardrum (P_D) is estimated by means of the pressure (P_E) that is measured at the internal sound receiver(14) by using an electroacoustic model of the ear canal.
10. Method according to one of the preceding claims, characterised in that a pressure on the eardrum (P_D) is determined by means of a pressure (P_E) measured at the internal sound receiver (14) and by means of the second correction filter (B) with the following equation: $${\mathrm{P}}_{\mathrm{D}}={\mathrm{P}}_{\mathrm{E}}\mathrm{B}$$

    
11. Electroacoustic system with an electroacoustic device (10) to at least partially occlude an ear canal, with a signal processing device (16) for processing an incoming signal from the device (10), the signal processing device (16) possesses at least one correction unit (17) configured to modify the incoming signal at the device (10) and to prepare an outgoing signal from the device (10), which serves to achieve an acoustic transparency, by which, based on the outgoing signal, a received signal can be generated on the eardrum which is adapted to correspond to a free-ear received signal at the eardrum in the case of a free ear canal without the device (10), the at least one correction unit (17) has a first correction filter (A) and a second correction filter (B), the first correction filter (A) of the at least one correction unit (17) being arranged upstream of the second correction filter (B) of the at least one correction unit (17), wherein the incoming signal is firstly modified by means of the first correction filter (A) so as to achieve acoustic transparency, wherein to determine the first correction filter (A) of the at least one correction unit (17) a total pressure (P_TOT) of an external acoustic signal within the ear canal at least partially occluded by the device (10) is equated by taking into account the first correction filter (A) with an expected target pressure (P_T,E), wherein the first correction filter (A), by taking into account a passageway pressure (P_HT) measured by means of inner receiver (14) associated with the device (10) and facing the eardrum of the ear, is determined with the following equation: $$A=\frac{P_{T,E}-P_{\mathit{HT}}}{P_{\mathit{tot}}-P_{\mathit{HT}}}$$

    

    and then the modified incoming signal is modified by means of the second correction filter (B) to filter out transmission effects in the area from the device (10) to the ear drum on the basis of the at least partial occlusion of the ear canal by the device (10).
12. Use of a method according to one of claims 1 to 10, wherein the method is integrated in a hearing protector, an in-ear headphone and/or in a hearing aid.
13. Use of an electroacoustic system (11) according to claim 11, wherein the electroacoustic system (11) is integrated in a hearing protector, an in-ear headphone and/or in a hearing aid.

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