Patent Application
20070274550
The microphone 20 captures audio signals which are supplied to the central processing unit 22 in order to generate an input audio signal for the output transducer 24. Usually processing of the audio signals provided by the microphone 20 occurs depending on the auditory scene as analyzed by the central processing unit 22 in order to optimize perception of sound by the user 14. In a binaural system the central processing unit 22 exchanges audio signals and control data with the receiver transmitter unit 18 which has been received by the antenna 16 from the other hearing aid via the link 26 or which are to be transmitted to the other hearing aid via the link 26. The receiver/transmitter unit 18 is controlled by the central processing unit 22. In the central processing unit 22 audio signals received from the other hearing aid, i.e. from the other ear, may be added to the audio signals from the microphone 20, and also processing of the audio signals from the microphone 20 may be performed by taking into account information provided from the other hearing aid, whereby the perception of sound by the user 14 can be significantly improved.
The output transducer 24 serves to simulate the user's hearing and may be an electro-acoustic transducer (i.e. a loudspeaker), an electro-mechanical output transducer mechanically coupled to the ear, or a cochlea implant.
Examples of binaural hearing aid systems comprising a wireless link between the hearing aids are given in U.S. Pat. No. 6,549,633 B1, US 2004/0037442 A1 and US 2006/0018496 A1.
During practical use of the hearing aids 10, 12 the link 26 may be disturbed by the presence of a source 28 of radio frequency signals interfering with the link 26 and having an amplitude changing periodically between a low amplitude regime (“idle time”) and a high amplitude regime (“burst”), i.e. the energy of the interfering RE signals changes periodically. An example of such interfering RE signal source 28 is a mobile phone which is used at one of the ears of the user 14 and hence in close proximity to one of the hearing aids 10, 12. Mobile phones usually emit time-division-multiple-access (TBMA) signals, which often obey the GSM standard.
An example of a GSM signal is shown in
Signals of similar structure and at similar frequency bands are also emitted by devices using the DECT standard, which is commonly used for cordless phones and which is divided into time frames of a length of 10 msec. which are divided into time slots having a duration of about 0.42 msec., or by devices using the Bluetooth standard, which has a burst repetition period of 1.25 msec., with each burst lasting for 0.37 msec.
Without counter-measures, the link 26 between the hearing aids 10 and 12 would be heavily disturbed and usually would break down during transmission of the bursts of an RF interfering device 28 if such device 28 was used at one of the ears of the user 14. In this respect it has to be noted that the bursts primarily would disturb reception of the signals transmitted via the link 26, while transmission of the signals essentially would not be affected. Due to the relatively small distance between the ears in most cases reception of the signals transmitted via the link 26 would be heavily disturbed by the RF interfering device 28 both in the case which the device 28 is used at that hearing aid which is presently receiving and in the case in which the device 28 is used at that hearing aid which is presently transmitting. However, there may be cases in which heavy disturbance of the reception occurs only if the interfering device 28 is used at that hearing aid which is presently receiving.
In order to avoid disturbance of the link 26—and in particular to avoid loss of data—during the presence of a RF interfering device 28 the binaural system is designed such that it is permanently detected whether a source 28 of RF signals interfering with the link 26 and having an amplitude changing periodically between a low amplitude regime and a high amplitude regime is present in the vicinity of one of the hearing aids 10, 12 (as already mentioned above, in some cases it may be sufficient to detect only whether such source 28 is present in the vicinity of that hearing aid which is presently receiving). During times in which no presence of an interfering RF source is detected, the binaural system is operated in a base mode, i.e. a conventional wireless data/audio signal exchange mode. As long as the presence of a source of interfering RF signals is detected, the system switches into an interference mode in which the transmission of signals via the link 26 is synchronized to the periodicity of the amplitude of the interfering RF signals in such a manner that the signals are transmitted via the link 26 only during the low amplitude regime, i.e. the idle times of the interfering RF signals.
In most cases it will be necessary that transmission from any of the two hearing aids 10, 12 occurs in the interference mode irrespective of the question at which of the two hearing aids 10, 12 the interfering device 28 is used. As already mentioned above, in some cases it may be sufficient that only transmission from that hearing aid at which the interfering device 28 is not used occurs in the interference mode while transmission from that hearing aid at which the interfering device 28 is used may occur in the base mode.
Further, in view of the fact that the interfering device 28 usually will be a phone, in the interference mode preferably audio signals captured by that hearing aid to which the interfering device 28 is closer are not only presented to the respective ear via the output transducer 24 of that hearing aid, but are also transmitted via the link 26 to the other hearing aid for being presented also to the other ear of the user.
According to one embodiment, the presence of the interfering device 28 may be detected by monitoring the quality of the link 26 by one or both of the hearing aids 10, 12. According to an alternative embodiment, one or both of the hearing aids 10, 12 may be provided with a dedicated circuit for this purpose.
Synchronization of the transmission of the signals via the link 26 in the interference mode may be achieved by measuring the amplitude of the interfering radio frequency signals in time domain and predicting the idle time periods, i.e. the periods of time during which the low amplitude regime will prevail. Preferably the system is designed such that it can be determined to which of the hearing aids 10, 12 the interfering device 28 is closer. According to one embodiment, this can be realized by monitoring the symmetry of the quality of the link 26 by the two hearing aids 10, 12. According to an alternative embodiment, to this end the audio signals captured by each of the hearing aids 10, 12 via the microphone 20 may be analyzed.
The control of the two hearing aids 10, 12 regarding the interference mode may be realized by a symmetric architecture or by a master/slave architecture; in the latter case one of the hearing aids 10, 12 would be the master while the other one would be the slave.
An example of the data/audio signal transmission in the interference mode is shown in the upper part of
According to an alternative embodiment, transmission of the signals in the interference mode may be controlled such that the signal is transmitted in packets A1, A2, B1, B2, etc. having a length of not more than half of the idle time period, i.e. the period length of the low amplitude regime, with each packet subsequently being transmitted twice. In this case no synchronization of the transmission with the idle time periods is necessary, since by reducing the packet length to half of the idle time period length and by transmitting each packet twice it is ensured that each packet is transmitted once completely within an idle time period without overlap with the bursts. This is also apparent from the lower part of
The invention is applicable not only to binaural hearing aid systems; rather, it is generally applicable to any hearing assistance system comprising a hearing instrument which is connected to a remote device, i.e. a device spaced apart from the hearing instrument, via a wireless link for receiving data/audio signals from that remote device. Consequently, the embodiment of
In
The hearing instrument 110 is worn at the better ear of the user 14, while the microphone unit 30 is worn at the worse ear. The microphone unit 30 comprises a microphone 32, a central processing unit 34, a receiver transmitter unit 36 and an antenna 38. The audio signals generated by the microphone 32 are processed in the central unit 34 and then are supplied to the receiver/transmitter unit 36 for being transmitted via the antenna 38 over the link 26 to the hearing instrument 110 in order to be presented via the output transducer 26 to the better ear of the user 14. In a BiCROS system these audio signals will be combined in the central processing unit 22 of the hearing instrument 110 with audio signals captured by the microphone 20 of the hearing instrument 110.
If the presence of an interfering device 28 at the hearing instrument 110 is detected, transmission of the audio signals from the microphone unit 30 will occur in the interference mode. In most cases this will also apply if an interfering device 28 is detected at the microphone unit 30. Detection of the presence of an interfering device 28 at the hearing instrument 110 or the microphone unit 30 may be performed by the hearing instrument 110 and/or the microphone unit 30. If detection of the interfering device 28 is not performed in the microphone unit 30, corresponding information has to be transmitted to the microphone unit 30 from the hearing instrument 110; such information may include the confirmation that transmission has to occur in the interference mode, information regarding where the interfering device 28 is located (i.e. at the hearing instrument 110 or the microphone unit 30), information regarding the burst length and the idle time length, and information regarding the phase of the interfering signal (this is necessary only if in the interference mode the transmission has to be synchronized to the phase of the idle times).
In
Usually the accessory device 40 will comprise at least an antenna 42, a receiver/transmitter unit 44 and a central processing unit 46. The central processing unit 46 controls the receiver/transmitter unit 44 and provides the data to be transmitted via the antenna 42 over the link 26 to the hearing instrument 210.
According to one embodiment, the accessory device 40 may serve as a remote control of the hearing instrument 210. In this case, it will comprise some kind of operating panel 48. Alternatively or in addition, the accessory device 40 may serve as an audio signal source for the hearing instrument 210. To this end, it may be provided with a microphone 50 and/or an input 52 for an external audio source 54, such as a phone, a television device, a hi-fi-system, etch.
Rather then being directly connected to the accessory device 40 via the input 52, such external audio source also could be represented by a device 56 which is connected to the accessory device 40 via a wireless link 58. Such external device 56 may include an antenna 60, a transmitter 62, a central unit 64, a microphone 66, an audio signal source 68 and/or an input 70 for an audio source 72.
In the embodiment of
In the above embodiments the antenna 16 and receiver/transmitter unit 18 have been shown as a part of the hearing instrument 10, 110, 210. However, according to an alternative embodiment, all elements necessary for the link 26 could be part of a separate receiver/transmitter unit which is mechanically and electrically connected to the hearing instrument 10, 110, 210, e.g. via an audio shoe (this is indicated by a dashed line around 16, 18 in
Moreover, in the above embodiments only periodic interfering FM signals have been discussed in which idle times and bursts are repeated subsequently. However, the present invention is generally applicable to any interfering FM signals which have a transmission power changing according to a predictable scheme between low power regimes and high power regimes. In that case, transmission of the signals from the remote device to the hearing device are synchronized to the detected power scheme of the interfering signals in such a manner that the signals are transmitted only during the low power regimes. To this end, the hearing device will identify the detected power scheme in order to predict the times of the low power regimes, e.g. with the help of a library of known transmission power schemes. According to an alternative embodiment, the transmission of the signals from the remote device to the hearing device is controlled such that the signals are transmitted in packets each having a length of not more than half the length of the shortest one of the low power regimes of the detected power scheme, with each packet subsequently being transmitted twice.
While various embodiments in accordance with the present invention have been shown and described, it is understood that the invention is not limited thereto, and is susceptible to numerous changes and modifications as known to those skilled in the art. Therefore, this invention is not limited to the details shown and described herein, and includes all such changes and modifications as encompassed by the scope of the appended claims.
