AU2007202880B2

AU2007202880B2 - Bluetooth transmission facility for hearing devices, and corresponding transmission method

Info

Publication number: AU2007202880B2
Application number: AU2007202880A
Authority: AU
Inventors: Thomas Lotter; Jurgen Reithinger
Original assignee: Sivantos GmbH
Current assignee: Sivantos GmbH
Priority date: 2006-06-26
Filing date: 2007-06-21
Publication date: 2009-07-23
Anticipated expiration: 2027-06-21
Also published as: EP1874088A3; JP2008011527A; AU2007202880A1; DE102006029196B4; EP1874088A2; DK1874088T3; CN101098168B; JP4749390B2; DE102006029196A1; CN101098168A; EP1874088B1

Description

S&F Ref: 812754 AUSTRALIA PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name and Address Siemens Audiologische Technik GmbH, of Gebbertstrasse of Applicant : 125, 91058, Erlangen, Germany Actual Inventor(s): Thomas Lotter, J~rgen Reithinger Address for Service: Spruson & Ferguson St Martins Tower Level 35 31 Market Street Sydney NSW 2000 (CCN 3710000177) Invention Title: Bluetooth transmission facility for hearing devices, and corresponding transmission method The following statement is a full description of this invention, including the best method of performing it known to me/us: 5845c(837969_ I ) - 1 BLUETOOTH TRANSMISSION FACILITY FOR HEARING DEVICES, AND CORRESPONDING TRANSMISSION METHOD 5 The present invention relates to a transmission facility for transmitting audio data to a hearing device, with a transmission device for sending audio data in a Bluetooth signal, a coder which is integrated into the transmission device, for compressing the audio data before its transmission and a relay station for converting the Bluetooth signal from the 10 transmission device into a signal for inductive transmission to the hearing device. Furthermore, the present invention relates to a corresponding method for transmitting audio data to a hearing device. There is an ever increasing need for the wireless broadband transmission of audio data for is speech or music, from televisions or hi-fi devices, to hearing devices. In particular, transmission should also be possible to a hearing device system with two hearing devices, for the binaural supply. For the purpose of cordless audio transmission to hearing devices, use is made mainly of 20 FM or infrared devices. These are devices which are worn in place of a hearing device, which are offered as plug-on modules for hearing devices or which are integrated into a hearing device with the need for significant additional space. For audio transmission, several electromagnetic transmission paths can basically be 25 considered. Thus it is possible, for example, to make use of high-frequency far-field transmission systems and inductive near-field transmission systems. By using a digital, inductive transmission system, it is possible to cover short distances (less than I to 2 m) to a hearing device with a saving of space and power. However, for audio transmissions from televisions or hi-fi systems, sensible operation requires a far-field transmission system for 30 larger distances (range approx. 10 m). From the post-published patent application DE 10 2005 005 603.2, a data transmission facility for wireless transmissions to a hearing device is known, which contains a high frequency receiving device for receiving a high-frequency, modulated signal from an 3s external transmission unit. A mixing device is used to mix the high-frequency modulated signal with a reference signal of a similarly high frequency, so that a modulated output -2 signal can be generated, the carrier frequency of which is at least one order of magnitude lower, and which is suitable for inductive transmission. Finally, the output signal is transmitted inductively to the hearing device by a transmission device. This conversion method results in a minimal delay time over the entire radio link, because it omits 5 completely any demodulation and decoding plus re-modulation and re-encoding. However, a disadvantage of this transmission is that the entire radio link must be individually established, because the data transmission rate in the high-frequency transmission section and the data transmission rate in the section using inductive transmission must be individually adjusted. 10 Thus, a need exists to provide a transmission facility and a corresponding transmission method which involves lower development costs. Disclosed herein is a transmission facility for the transmission of audio data to a hearing 15 device, comprising: a coder for compressing the audio data, said coder working at a lower sampling rate than the standard A2DP coder, such that said compressed audio data is suitable for inductive transmission; a transmission device for transmitting the compressed audio data in a Bluetooth 20 signal, said transmission device transmitting according to the Bluetooth A2DP protocol, wherein said coder is integrated into the transmission device; and a relay station for receiving the Bluetooth signal from the transmission device and inductively transmitting said compressed audio data to the hearing device without re 25 coding the audio data. Correspondingly, in accordance with the present disclosure, a method a method for transmitting audio data to a hearing device, comprising the steps of: encoding the audio data, said encoding being performed using a lower sampling 30 rate than for a standard A2DP coder, such that said encoded audio data is suitable for inductive transmission; transmitting the encoded audio data in a Bluetooth signal to a relay station, said transmission being effected in accordance with the Bluetooth A2DP protocol; receiving said encoded audio data from said Bluetooth signal at a relay station; and 35 inductively transmitting said encoded audio data from said Bluetooth signal without re-coding the audio data. 2080485-1 -3 It is thus advantageously possible to make use of standardized components such as Bluetooth transmitters and Bluetooth receivers, together with the appropriate Bluetooth transmission protocol. The standardized components of the BT transmission system are tailored for audio applications (e.g. error protection). 5 The transmission of data in accordance with an embodiment of the present disclosure can if necessary be bidirectional. It is thus also possible for data from the hearing device to be communicated to an external device over the partially standardized transmission link. 10 The relay station will preferably be integrated into a remote control for the hearing device or hearing devices, as applicable, or possibly even into a television remote control, for example. The user would thereby not need an additional device for the wireless data transmission. 15 It is expedient if the audio bandwidth after the compression by the coder is less than 15 kHz. In particular, the audio bandwidth will lie between 8 and 12 kHz. By this means, the audio stream will be compressed as far back as the transmission side in such a way that no unprocessable data arrives at the hearing device. 20 It is further advantageous if the data transmission rate for the Bluetooth signal is under 150 kbit/s. This means that no special compression must be effected for an inductive transmission in the baseband. The present invention will now be explained in more detail by reference to the attached 25 drawings, which show: FIG 1 a transmission system with a relay station for decoding and re-encoding, FIG 2 a transmission system in accordance with an embodiment of the invention, with 30 a relay station and no re-encoding. The exemplary embodiment outlined in more detail below represents a preferred form of embodiment of the present invention. However, so that the invention can be better understood, a transmission system in accordance with the prior art as known internally, 3s which is shown schematically in FIG 1, will first be explained. 2080485_1 - 3a As shown for the system in FIG 1, a stereo audio signal 1 is to be transmitted from a television or from a hi-fi system to a hearing device or a hearing device system for binaural feed, as applicable. The audio signals I are sampled and encoded in a Bluetooth transmitter 3. During this encoding, the data is compressed and combined in blocks. The Bluetooth s transmitter 3 supports several standard coders, of which one coder 4 can optionally be used 2080485.1 -4 for the transmission. In Bluetooth A2DP the audio signal I is typically sampled at 44.1 or 48 kHz, so that an audio bandwidth of 20 to 24 kHz results for the transmitted signal. The data transmission rate r-bt is typically 230 to 350 kbit/s. The standard Bluetooth transmission link 5 permits wireless communication over a range of up to approx. 10 m. 5 A standard Bluetooth receiver with a compatible Bluetooth decoder 7 is arranged in a remote control 6, in order to decode the encoded audio data on the Bluetooth transmission link 5. For the subsequent inductive transmission to the hearing device system 2, the data transmission rate must be reduced to the value r hg. For this reason, a hearing device coder 10 8 is provided, in the remote control 6, which reduces the data transmission rate appropriately and supplies an audio bandwidth of 8 to 10 kHz. Encoded in this way, the data is sent over the inductive transmission link 9 to the hearing device system 2. Each hearing device in the hearing device system 2 has an appropriate hearing device decoder 10, 11. 15 Thus, the greater distance from a television or a hi-fi system to the hearing device can be bridged with minimal effort and at minimal costs by using a standard transmission method to a hearing device remote control. The Bluetooth method is used as the standard transmission method, this representing the most widespread standard for cordless stereo 20 audio transmissions within a house. The "last yard" from the remote control to the hearing device is then bridged inductively. In concrete terms, the audio signal is digitized in the Bluetooth transmission station 3 and, using the standardized audio transmission protocol A2DP, is transmitted to the relay 25 station, namely the remote control 6. This standard protocol stipulates support for a license-free codec, namely SBC. As well as this, other defined codecs can also be used, e.g. MP3, although these are not suitable for TV operation (because of the high algorithmic delay). In addition, the standard offers the possibility of defining/using a manufacturer dependent codec. 30 As already mentioned above, comparatively high data volumes are transmitted according to the standard on the Bluetooth link 5. For SBC, the data transmission rate is rbt = 230 to 350 kbit/s. However, the transmission to the hearing devices should be effected with the smallest possible components and saving as much current as possible. For this reason, an 3s inductive transmission link 9 is selected here, for which however the data transmission rate must be reduced in order to increase the efficiency and to permit a corresponding power -5 saving. The data reduction is effected by the recoding of the Bluetooth A2DP data stream to a hearing device data stream in the relay station or the remote control 6, as applicable. The solution depicted in FIG 1 for the wireless radio transmission link does, however, have s some disadvantages. On the one hand, the Bluetooth data transmission in accordance with the standard with its high bandwidth is inefficient for operation with a hearing device. The reason for this lies in the fact that, because of different quality requirements, hearing devices are normally operated with a lower audio bandwidth (approximately 8 to 10 kHz) than audio applications for those with normal hearing (greater than 20 kHz). In addition to 10 this, the recoding in the relay station leads to a reduced audio quality, and produces an increased current consumption, as a result of which the endurance of the relay station is reduced. A further disadvantage consists in the fact that the delay time for speech and music, from the television to the hearing device, is increased, because of the duplicated encoding delay (long audio blocks on the Bluetooth link) and the processing delays of the 15 remote control. This must be considered critical in that synchronicity ought to be ensured between the audio transmission, from the television to the hearing device, and the images, and that the overlaying of direct sound from the television by the transmitted audio signal produces an unwanted coloration or echoing of the music or speech signal. In accordance with the present disclosure therefore, the system which is illustrated in 20 principle in FIG 2 is used. In a transmission station 13, the TV or hi-fi signal 1 is transposed with the aid of a hearing device coder 14 into a desired hearing device format. This is distinguished by an audio bandwidth of 8 to 10 kHz. Apart from this, the signal is so encoded by the hearing device coder 14 as to produce a data rate r-hg which is suitable for the following inductive transmission link. This is realized by an appropriate block 25 length for the data blocks. The hearing device coder 14 by which the stereo signal is, after digitization, compressed with a hearing device sampling rate, acts as an alternative to the SBC coder, conforming to the standard, in the Bluetooth A2DP application. The SBC can also be supported in the 30 transmitter, but is not used for the hearing device application. The remaining part of the physical transmission according to the Bluetooth A2DP protocol can be applied without change for the Bluetooth transmission link 15. In the remote control 16, the Bluetooth data stream is received in the hearing device format 35 by a standard Bluetooth receiver, and can be passed on to an inductive transmitter in the remote control 16 without recoding or conversion of the digital sampling rate. The 'nbc 1rk -6 Bluetooth receiver and the inductive transmitter are therefore symbolized in FIG 2 as a bypass 17. The remaining data transmission link, namely the inductive transmission link 9 together with the hearing device system 2 with the hearing device coders 10 and 11, corresponds to that of FIG 1. Thus, for the entire transmission shown in FIG 2 the payload s data rate and the clock rate on the Bluetooth link 15 correspond to that on the inductive transmission link 9, i.e. rbt = rhg. Because the Bluetooth standard is used, the major part of the transmission link to the hearing device frame can be simply and cost-effectively realized, with little development 10 work. The "last yard" to the hearing device is effected in a particularly energy-saving way by means of the inductive link 9. The relocation of the hearing device coder and the sampling at the hearing device clock rate in the Bluetooth transmission station 13 brings the following advantages: 15 a) The efficiency can be raised in the transmission station and in the remote control. Namely, the Bluetooth transmission in accordance with the A2DP protocol can be carried out at a significantly lower data transmission rate than in the standard application using SBC. This will lower the current consumption in the transmission and relay station. Apart from which, the demanding recoding in the remote control no 20 longer takes place, which leads to further current savings. Hence a longer battery between-charge time or less frequent battery change, as applicable, can be achieved. b) Because both Bluetooth codec (coding/decoding) and also hearing device codec represent transformations with losses, the audio quality of the overall signal is raised, 25 because in the system in accordance with the embodiment of the invention shown in FIG 2 it is only necessary to encode/decode once. c) An important quality attribute of the overall system is the delay of the audio signal due to the transmission. On the one hand, in the TV application direct sound from the 30 television is overlaid at the hearing device wearer's ear with the signal transmitted by radio, which leads to annoying coloration or echoing. On the other hand, it is necessary to ensure the synchronicity of the image with the sound. With the method in accordance with an embodiment of the invention, the delay time is minimized by the elimination of an encoding delay and a processing delay in the remote control.

Claims

1. A transmission facility for the transmission of audio data to a hearing device, comprising: a coder for compressing the audio data, said coder working at a lower sampling 5 rate than the standard A2DP coder, such that said compressed audio data is suitable for inductive transmission; a transmission device for transmitting the compressed audio data in a Bluetooth signal, said transmission device transmitting according to the Bluetooth A2DP protocol, wherein said coder is integrated into the transmission device; 10 and a relay station for receiving the Bluetooth signal from the transmission device and inductively transmitting said compressed audio data to the hearing device without re-coding the audio data. 15

2. The transmission facility as claimed in claim 1, wherein data can be transmitted bidirectionally.

3. The transmission facility as claimed in either one of claims I and 2, wherein the relay station is integrated into a remote control. 20

4. The transmission facility as claimed in any one of the preceding claims, wherein the audio bandwidth after compression by the coder is less than 15 kHz.

5. The transmission facility as claimed in claim 4, wherein the audio bandwidth 2s lies between 8 and 12 kHz. 21103361 IRN: 812754 -8

6. The transmission facility as claimed in any one of the preceding claims, wherein the data transmission rate in the Bluetooth signal is below 150 kbit/s.

7. A method for transmitting audio data to a hearing device, comprising the steps 5 of: encoding the audio data, said encoding being performed using a lower sampling rate than for a standard A2DP coder, such that said encoded audio data is suitable for inductive transmission; transmitting the encoded audio data in a Bluetooth signal to a relay station, said 10 transmission being effected in accordance with the Bluetooth A2DP protocol; receiving said encoded audio data from said Bluetooth signal at a relay station; and inductively transmitting said encoded audio data from said Bluetooth signal without re-coding the audio data. 15

8. The method as claimed in claim 7, wherein the data can be transmitted bidirectionally.

9. The method as claimed in either one of claims 7 and 8, wherein the audio 20 bandwidth after encoding is less than 15 kHz.

10. The method as claimed in any one of claims 7 to 9, wherein the data transmission rate in the Bluetooth signal is below 150 kbit/s. 2110336_1 IRN: 812754 -9 9. The method as claimed in either one of claims 7 and 8, wherein the audio bandwidth after encoding is less than 15 kHz. 10. The method as claimed in any one of claims 7 to 9, wherein the data 5 transmission rate in the Bluetooth signal is below 150 kbit/s.

11. A transmission facility for the transmission of audio data to a hearing device, said transmission facility being substantially as described herein with reference to the accompanying drawings. 10

12. A method for transmitting audio data to a hearing device, said method being substantially as described herein with reference to the accompanying drawings. DATED this twenty-eighth Day of May, 2009 15 Siemens Audiologische Technik GmbH Patent Attorneys for the Applicant SPRUSON & FERGUSON 2110336_1 IRN: 812754