EP1976332A2 - Method and device for producing synthetically produced signals through a binaural listening system - Google Patents

Abstract

The method involves providing a binaural listening system with two hearing aids (HG1, HG2), and enabling reproduction of a synthetically produced signal (SIG2) by the aid (HG2) around a defined time interval after reproduction of a synthetically produced signal (SIG1) by the aid (HG1). A time delay is measured, so that a mark of sound expansion is developed by a hearing system carrier, and a temporal distance between reproductions of synthetically produced signals lies at a range of 1 millisecond to 50 milliseconds approximately. An independent claim is also included for a device for reproducing synthetically produced signals through a binaural listening system.

Description

The present invention relates to a method for reproducing synthetically generated signals by a binaural hearing system. Moreover, the invention relates to a device for reproducing synthetically generated signals by a binaural hearing system. In this case, synthetically generated signals in this description are to be understood as all signals generated in the hearing system or in a system connected thereto. The term thus includes, inter alia, signals generated by oscillators but also signals which are read from digital memories and subsequently reproduced in analog form.

In many cases, a hearing aid with two hearing aids (binaural hearing aid, so-called binaural care) is required or useful for the adequate care of a patient with a hearing impairment. Today, almost exclusively digitally programmable hearing systems are used, ie hearing systems whose electroacoustic properties can be adjusted externally via a computer or computer ("adapted") and must. The main advantage of (programmable) programmable hearing instruments is that a variety of electro-acoustic parameters can be adjusted to more precisely compensate for hearing loss. The signal processing can take place in these hearing aids in an analogous manner (digitally programmable analog hearing systems) or in a digital manner (fully digital hearing systems).

Fully digital hearing aids are hearing systems that convert the analog microphone signal into a digital signal. The digital Signal is then processed according to the commands of the programmed software (algorithm) and on-chip integrated circuits. Finally, the digital signals are converted back to analog signals and forwarded to the listener. The incoming signal is measured at certain intervals (signal sampling). The more frequent the signal sampling, the better the reproduction of the input signal. The digitization allows much more complex analysis and filtering with regard to an optimum useful signal / noise ratio than was possible with analog systems.

Wirelessly connected hearing aid systems enable communication between the right and left hearing aids in the case of binaural care. However, the implementation of wirelessly received instructions, such as program switching, and in particular the acoustic output is not synchronized in both hearing aids. A time offset is particularly noticeable in the output of beeps ("Beeps"). If synthetically generated signals are to be output binaurally in such a hearing system, a specific synchronizing behavior of the two devices is therefore necessary in order to avoid disturbing effects for the hearing device system carrier.

From the EP 1 750 482 A2 a method for synchronizing signal tones is known in which counters are equated in both hearing aids of the binaural hearing system by a synchronization signal. With this solution a very extensive synchronization is possible; However, the effort to implement this solution is relatively high.

The present invention is therefore based on the problem of the synchronization of hearing aids Binaural hearing system in the reproduction of synthetically generated signals with the least possible technical effort and therefore to solve as cost-effective.

This object is achieved by a method and a device for the reproduction of synthetically generated signals by a binaural hearing system according to one of the independent patent claims. The invention is based on the psychoacoustic knowledge that small time shifts in the reproduction, as they arise in a not quite perfect synchronization, is perceived by the hearing aid wearer an undesirable shift of the virtual switching source in space in the direction of one of the devices. If, on the other hand, the time shift during playback is in a somewhat higher range, then this shift is perceived by the hearing system wearer as a sound expansion (reverberation, reverberation) that is not perceived as disturbing, but which actually enhances the subjective impression of the sound somewhat.

The basic idea of the present invention is therefore based on a waiver of as complete as possible synchronization of the two hearing aids of the binaural hearing system under conscious acceptance of a time shift, which, however, should be such that the result is not perceived by the hearing aid wearer as disturbing.

• Figur 1 in schematischer Weise den typischen Aufbau eines binauralen Hörsystems zeigt,
• Figur 2 ein Sequenzdiagramm zur schematischen Veranschaulichung des erfindungsgemäßen Verfahrens gemäß einem bevorzugten Ausführungsbeispiel,
• Figur 3 ein weiteres Sequenzdiagramm zur schematischen Veranschaulichung eines weiteren bevorzugten Ausführungsbeispiels des erfindungsgemäßen Verfahrens zeigt und
• Figur 4 ein weiteres Sequenzdiagramm zur schematischen Veranschaulichung eines weiteren bevorzugten Ausführungsbeispiels des erfindungsgemäßen Verfahrens zeigt.

The present invention will now be described with reference to the accompanying figures and with the aid of preferred embodiments, wherein

• FIG. 1 schematically shows the typical structure of a binaural hearing system,
• FIG. 2 a sequence diagram for schematically illustrating the method according to the invention according to a preferred embodiment,
• FIG. 3 a further sequence diagram for schematically illustrating a further preferred embodiment of the method according to the invention shows and
• FIG. 4 a further sequence diagram for schematically illustrating a further preferred embodiment of the method according to the invention shows.

The embodiments described in more detail below represent preferred embodiments of the present invention. The person skilled in the art will be able to easily find further embodiments on the basis of this description, the complete presentation of which would go beyond the scope of this description.

An inventive binaural hearing system consists of a left hearing aid HG1 and a right hearing aid HG2. Between two hearing aids HG1 or HG2 a preferably low-speed data connection STX for the transmission of control or synchronization signals is present. This data connection normally meets low requirements and typically only intermittent and not necessarily continuous signals are exchanged.

In the in FIG. 1 In the example shown, the hearing aid HG1 supplies the left ear LE, whereas the hearing aid HG2 supplies the right ear RE of the hearing system wearer. In FIG. 1 Furthermore, a remote control RC is shown, as it is typically used today with wireless binaural hearing systems. there This remote control can communicate with both hearing aids or even with only one hearing aid (CS1, CS2).

In the situation with which the present invention is concerned, acoustic signals SIG1 and SIG2 are to be output to the hearing system wearer by the hearing aids of the binaural hearing system. Such a situation may e.g. present when the hearing aid user wants to put the hearing aids via the remote control RC in a (different) operating state and this change is now reported back to the hearing aid user. Other automatically generated signals may e.g. be issued during a program switching, or one for reporting status information of the system to the hearing aid users, etc. The signals to be output here are typically generated synthetically. For playback, these digital signals - usually after previous digital-to-analog conversion - output on the speaker of the respective hearing aid.

Typically, the signaling is triggered by one of the two hearing aids connected to a hearing system. The reproduction should be such that it is binaurally perceived as a uniform event. For this purpose, a transmission of the trigger pulse between the two devices is necessary. This transmission typically takes place by electromagnetic or magnetic-inductive means of digital transmission. In principle, all known single and multicarrier methods, such as BPSK, QPSK, QAM, OFDM, etc. as well as time or frequency division multiplexing (TDMA, CDMA, etc.) are suitable for modulation. Typically, channel coding methods are used for error detection and error correction, which requires decoding at the receiver. Furthermore, a packet-wise multiplexed transmission of various data is often provided, which is a necessity of buffers leads. This results in a total that a transmission can not be instantaneous, but with a certain time delay, which can be roughly estimated at least on the sending side but in sum can not always be determined exactly.

Ideally, both devices HG1 or HG2 would be exactly synchronized. Then the signals could be delivered exactly synchronously and thus - as actually desired - be perceived in the middle. A suitable method was in the EP 1 750 482 A2 described. Practically, however, an exact synchronization means an increased amount of hardware and energy, which should be saved. According to the present invention, a perfect synchronization is deliberately dispensed with; instead, after a first signal SIG1 has been reproduced by the first hearing device HG1, the reproduction of a second signal SIG2 by the second hearing device HG2 is additionally delayed by a defined second time interval DT2. Of course, the order of the hearing aids can also be reversed. It is meant by the term "additionally delayed" that in addition to the delays inevitably occurring due to the transmission methods described above, a further deliberate delay is made. This further deliberate delay is referred to below as DT2.

In the in FIG. 2 As shown, the hearing aid HG1, which is assigned to the left ear LE of the hearing system wearer, is operated as a "master", whereas the hearing aid HG2, which is assigned to the right ear RE, reacts as a "slave". In this example, the remote control RC sends a signal CS1 to the hearing aid HG1, whereupon the hearing aid HG1 outputs the signal SIG1 to the left ear LE after a time interval t1. The size of the time interval t1 is essentially by the time required for the signal processing in the hearing aid HG1 conditional. After expiration of a further time interval t2, the hearing aid HG1 sends a signal STX to the hearing aid HG2. The hearing aid HG2 then sends with a time delay t3 a corresponding signal to the device E, which measures the additional time delay DT2 according to its purpose and causes. After expiration of this time interval DT2, the device E transmits a corresponding signal back to the hearing aid HG2, which then outputs the signal SIG2 to the right ear RE after a further time interval t4 has elapsed.

In a modification of this embodiment, one could also send the signal STX from the hearing aid HG1 to the hearing aid HG2 before the hearing aid HG1 outputs the signal SIG1 to the left ear LE. In this case, it would then make sense to dimension the time interval DT2 correspondingly larger, because the triggering signal STX arrives earlier at the hearing aid HG2.

In the by FIG. 2 schematically illustrated embodiment of the process, it makes sense if the device E is housed for the design and generation of the time delay DT2 in the hearing aid HG2.

In another, in FIG. 3 schematically illustrated preferred embodiment of the invention, the device E for measuring the time delay DT2 is housed in the hearing aid HG1. As in the previous case, the remote control sends a signal CS1 to the hearing aid HG1, which, after a time interval t1 has elapsed, sends a signal s11 to the device E which calculates the appropriate magnitude of the time delay DT2. After the expiration of a time interval t2, the device E transmits the result in the form of the signal s12 back to the hearing aid HG1, which then after expiration of a Interval t3 the signal SIG1 outputs to the left ear LE. After expiration of the time interval DT2 measured from the time of reception of the signal s12, the hearing aid HG1 transmits the signal STX to the hearing aid HG2, which then outputs the signal SIG2 to the right ear after the expiration of the time interval t4.

The person skilled in the art will readily recognize from the description of the invention and the exemplary embodiments presented herein that further modifications of the exemplary embodiments described here are possible. Ultimately, it is crucial that the total time delay in the signal output between the two ears of the hearing aid wearer is within a range which leads to the desired psychoacoustic result of a not perceived as disturbing perception.

Psychoacoustic investigations now show that it is possible to dimension the additional second time delay DT2 in such a way that the hearing aid wearer gets the impression of a sound widening. The term "sound expansion" is understood by the psychoacoustic as a sound change, which can also be called reverberation (reverberation). Such sound changes are perceived by the hearing aid wearer as a rule rather than pleasant than annoying.

Such a desirable sound change arises as psychoacoustic experiments show in this context when the second time delay DT2 is in the range of about 1 ms to about 50 ms. Selecting the time delay DT2 in this range generally ensures that the perception of the hearing aid wearer will not result in either an undesirable spatial characteristic of the virtual switching source, or a complete disintegration of the signals to be reproduced into two separate signals. If, however, the delay between the two devices is too large, the impression of a uniform hearing event is lost. An echo is created; the stereo signal thus decays into two individually perceptible mono signals.

In this regard, experiments show that the second time delay DT2 should advantageously range between about 4 ms to about 20 ms. Optimal audio impressions result when the second time delay DT2 is in the range of about 5 ms to about 15 ms.

It should be noted in this information that the auditory impression ultimately depends on the total time delay between the reproduction of the signals SIG1 or SIG2 to the ears LE or RE. As long as the response times and transmission times t1, t2, t3 or t4 are much smaller than the time delay DT2, the influence of these additional times can be neglected. However, if this is no longer the case for the reasons of the selected transmission methods between the hearing aids, then the influence of these transmission and response times on the total time delay must be taken into account accordingly when dimensioning the additional time delay DT2. However, this should not be difficult for a person skilled in the art on the basis of the description presented here. In these cases, the stated time scales are therefore based on the total time delay and not on the time interval DT2 alone. In the normal case, however, the influence of the times t1, t2, t3 and t4 should be so small that they can be neglected compared to the time delay DT2.

• Jens Blauert: Räumliches Hören. S. Hirzel-Verlag, Stuttgart 1972, ISBN 3-7776-0250-7
  1. 1. Nachschrift. Neue Ergebnisse und Trends seit 1972. 1985, ISBN 3-7776-0410-0
  2. 2. Nachschrift. Neue Ergebnisse und Trends seit 1982. 1997, ISBN 3-7776-0738-X
• Jens Blauert: Spatial Hearing. The Psychophysics of Human Sound Localization. The MIT Press, USA-Cambridge MA 1. Auflage, 1983, ISBN 0-262-02190-0 Revised Edition, 1996, ISBN 0-262-02413-6
• Jens Blauert: An Introduction to Binaural Technology. In: Robert H. Gilkey, Timothy R. Anderson (Hrsg.): Binaural and Spatial Hearing in Real and Virtual Environments. Lawrence Erlbaum, USA-Mahwah NJ 1996, S. 593-609, ISBN 0-8058-1654-2 Jens Blauert (Hrsg.): Communication Acoustics. Springer, Berlin/Heidelberg/New York 2005, ISBN 3-540-22162-X

According to a further preferred embodiment of the invention, further improvements of the sound impression in the hearing system wearer can be achieved in that the signal level of the later reproduced signal SIG1 or SIG2 is raised relative to the signal level of the previously reproduced signal SIG2 or SIG1 during reproduction. As a result, any lateralization effects still present may be further reduced individually by the law of the first wavefront (also referred to as the "precedence effect"). A level increase in the context of this procedure, also referred to as "trading", should be in the range between 0 and 12 dB, particularly advantageously and preferably in the range between 0 and 3 dB. For more information on the appropriate design of this leveling and the psychoacoustic fundamentals, the reader takes, for example, the publication J. Blauert, "Spatial hearing", S. Hirzel-Verlag, Stuttgart 1972, ISBN 3-7776-0250-7 , In addition, the following publications of the same author contain basic information that can give the expert valuable information on possible embodiments of the invention:

• Jens Blauert: Spatial listening. S. Hirzel-Verlag, Stuttgart 1972, ISBN 3-7776-0250-7
  1. 1. Postscript. New results and trends since 1972. 1985, ISBN 3-7776-0410-0
  2. Second Postscript. New results and trends since 1982. 1997, ISBN 3-7776-0738-X
• Jens Blauert: Spatial Hearing. The Psychophysics of Human Sound Localization. The MIT Press, USA-Cambridge MA 1st Edition, 1983, ISBN 0-262-02190-0 Revised Edition, 1996, ISBN 0-262-02413-6
• Jens Blauert: An Introduction to Binaural Technology. In: Robert H. Gilkey, Timothy R. Anderson (ed.): Binaural and Spatial Hearing in Real and Virtual Environments. Lawrence Erlbaum, USA-Mahwah NJ 1996, pp. 593-609, ISBN 0-8058-1654-2 Jens Blauert (ed.): Communication Acoustics. Springer, Berlin / Heidelberg / New York 2005, ISBN 3-540-22162-X

Further improvements of the hearing impression are possible according to a further preferred embodiment, when a signal inversion is made in one of the two hearing aids. The basics of this are also described in the publications by Blauert. Further information can be found in the diploma thesis "On Differences in Listening Perception in Wave Field Synthesis and Stereofonia in Comparison to Natural Listening" by Dominik Wegmann, Institute for Hearing and Audiology, University of Applied Sciences Oldenburg / Ostfriesland / Wilhelmshaven, Faculty of Civil Engineering and Geoinformation (B + G) , Ofener Str. 16, D-26121 Oldenburg (http://www.irt.de/IRT/publikationen/Diplomarbeiten/DA Wegmann.pdf). The contents of all publications cited herein are hereby expressly incorporated by reference into the disclosure of the present specification.

In principle, however, it must always be true that the maximum transmission time must not be greater than the upper limit of the preferred range for the effective time delay between the outputs of the signals SIG1 and SIG2. Should the transmission time between the hearing aids be particularly large in special cases for technical reasons, then a delay in the hearing aid HG1 may be provided instead of the delay in the hearing aid HG2. This can be done, for example, in the FIG. 4 shown situation by appropriate dimensioning of the time interval DT1 done, which - depending on the variant - DT1 may be smaller than, equal to or greater than DT2.

The present invention is advantageously realized with a device E for reproducing synthetically generated signals in a binaural hearing system, which is suitable for the purpose Dimensioning and possibly generation of the time delay DT2 ensures. In any case, the time delay DT2 should be measured so that the hearing aid wearer gets the impression of a sound expansion. This is generally achieved by setting the time delay DT2 such that the total time delay between the playback of the signals SIG1 and SIG2 is within the psychoacoustically useful time ranges.

Claims (17)

Method for reproducing synthetically generated signals (SIG1, SIG2) by a binaural hearing system (HS) comprising two hearing aids (HG1, HG2), in which - after a first signal (SIG1) has been reproduced by the first hearing aid (HG1) - a Playback of a second signal (SIG2) by the second hearing aid (HG2) is additionally delayed by a defined second time interval (DT2). The method of claim 1, wherein the additional second time delay (DT2) is dimensioned so that the hearing aid wearer the impression of a sound expansion arises. The method of claim 2, wherein the additional second time delay (DT2) is sized such that the time interval between the reproduction of the synthesized signals (SIG1, SIG2) is in the range of about 1 ms to about 50 ms. The method of claim 2, wherein the additional second time delay (DT2) is sized such that the time interval between the reproduction of the synthesized signals (SIG1, SIG2) is in the range of about 4 ms to about 20 ms. The method of claim 2, wherein the additional second time delay (DT2) is sized such that the time interval between the reproduction of the synthesized signals (SIG1, SIG2) is in the range of about 5 ms to about 15 ms. Method according to one of the preceding claims, in which the signal level of the subsequently reproduced signal (SIG1, SIG2) is raised from the signal level of the previously reproduced signal (SIG2, SIG1) during playback. The method of claim 6, wherein the level increase is in the range of about 0 to 12 dB. The method of claim 6, wherein the level increase is in the range of about 0 to 3 dB. Method according to one of the preceding claims, in which a signal inversion is performed in one of the two hearing aids. Method according to one of the preceding claims, in which the reproduction of the first signal (SIG1) by the first hearing device (HG1) is delayed by a first defined time interval (DT1). Device (E) for influencing the reproduction of synthetically generated signals (SIG1, SIG2) in a binaural hearing system comprising two hearing aids (HG1, HG2), in which - after a first signal (SIG1) has been reproduced by the first hearing device (HG1) - Playback of a second signal (SIG2) by the second hearing aid (HG2) by a defined second time interval (DT2) is additionally delayed. Device (E) according to claim 11, wherein the additional second time delay (DT2) is dimensioned so that the hearing aid wearer the impression of a sound expansion arises. Device (E) according to one of claims 11 or 12, which is designed so that the signal level of the later reproduced signal (SIG1, SIG2) compared to the signal level of previously played back (SIG2, SIG1) during playback. Device (E) according to any one of claims 11, 12 or 13, which is designed so that a signal inversion can be made in one of the two hearing aids. Device (E) according to any one of claims 11 to 14, which is designed so that the reproduction of the first signal (SIG1) by the first hearing aid (HG1) by a first defined time interval (DT1) can be delayed. Device (E) according to one of claims 11 to 15 with a function block (FBM) for measuring the transit time of the signal transmission between the two hearing aids (HG1, HG2). Device (E) according to one of claims 11 to 16 with a function block (FBA) for evaluating the measured transit time of the signal transmission between the two hearing aids (HG1, HG2) for the purpose of defining at least one of the time intervals (DT1, DT2).

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