JP2008271549A - Hearing device with interference reduced receiver operation and corresponding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heating device which enables even a hearing aid that has wireless transmission to other devices, to operate while saving receiver currents in the hearing aid. <P>SOLUTION: The hearing device comprises a transmission device 15 for wireless data transmission in main frequency bands, a speaker 14 and an operating device 12 for operating the speaker 14 according to an operating signal, wherein a frequency spectrum of the operating signal has a substantial notched area in the main frequency bands. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a transmission unit for wireless data transmission in a main frequency band, a speaker, and a listening device having an operating device for operating a speaker by an operating signal. The invention further relates to a corresponding method for operating the listening device. Here, the concept of listening device means in particular a hearing aid, a headset, headphones and other devices that can be worn on the head.

  Hearing aids are wearable listening devices used for the treatment of hearing impaired people. In order to meet a large number of individual requirements, hearing aids come in a variety of structural types, such as ear-hung hearing aids (HdO) and ear canal hearing aids (IdO), and for example, Concha hearing aids or canal hearing aids. (CIC) is available. An exemplary hearing aid is worn in the outer ear or in the ear canal. Furthermore, bone conduction hearing aids, implantable or vibrotactile hearing aids are also used on the market. In so doing, the impaired auditory stimulation is performed mechanically or electrically.

  Hearing aids in principle have an input transducer, an amplifier and an output transducer as essential components. The input transducer is typically at least one of a sound receiver such as a microphone and an electromagnetic receiver such as an induction coil. The output transducer is most often realized as an electroacoustic transducer, for example a small speaker, or as an electromechanical transducer, for example a bone conduction receiver. The amplifier is usually integrated in the signal processing unit. This principle structure is shown in FIG. 1 for an example of a hook-on hearing aid. In the hearing aid housing 1 for wearing after the ear, one or more microphones 2 are incorporated for taking sounds from the surroundings. Similarly, the signal processing unit 3 incorporated in the hearing aid housing 1 processes the microphone signal and amplifies it. The output signal of the signal processing unit 3 is transmitted to a speaker or receiver 4, and the speaker or receiver outputs an acoustic signal. In some cases, the sound is transmitted to the eardrum of the hearing aid wearer via an acoustic tube that is fixed in the ear canal by otoplasty. The power supply of the hearing aid and in particular the signal processing unit 3 is likewise effected by a battery 5 incorporated in the hearing aid housing 1.

  For example, pulse density modulation (PDM) or pulse width modulation (PWM) is often used to operate a hearing aid speaker or handset. Digital operation has the advantage that the digital-to-analog converter stage can be eliminated in the digital hearing aid. Digital actuating circuits also have a significantly higher efficiency than analog actuating circuits. In contrast, analog operating circuits are less disturbing, i.e. analog operating circuits have few harmonic components in the frequency spectrum limited to acoustic signals. Highly prominent harmonics in digital operation are wireless transmission of data between hearing aids and between hearing aids and external accessories (remote controls, wireless programming devices, wireless relay devices, etc.) It becomes an obstacle.

  One possible solution to this problem may be in the following compromise. That is, in the hearing aid having wireless transmission, the handset is operated in an analog manner, and in the hearing aid having no wireless function, digital operation is performed to save current. However, hearing aids with wireless transmission along with them cannot benefit from digital actuation that saves current.

  It is therefore an object of the present invention to enable a digital operation that saves the current of the speaker of the listening device, especially for a listening device that functions digitally. A further object is to provide a corresponding method for operating the listening device.

  According to the present invention, this problem is solved in a listening device comprising a transmission device for wireless data transmission in the main frequency band, a speaker, and an operating device for operating the speaker by an operating signal. The spectrum is solved by having a substantial notch region in the main frequency band region.

  Furthermore, the present invention provides a method for operating a listening device by wireless data transmission in the main frequency band and activation by a speaker activation signal of the listening device, wherein the frequency spectrum of the activation signal is in the main frequency band. The region has a substantial notch region.

  By separating the signals for data transmission and speaker operation in the frequency domain, there is little mutual interference, so that the listening device configured for wireless data transmission also digitally connects the internal handset or speaker. Can be operated.

  Advantageously, the actuating signal of the actuating device is pulse density modulated or pulse width modulated. Thereby, the inductive speaker acting as a low-pass filter can be operated without the high signal processing cost of the digital signal processing circuit.

  Data transmission by the transmission device can be performed in a plurality of frequency bands in a wide band, and the frequency spectrum of the operation signal can have a substantial notch region in each region of the frequency band. In addition, the principle according to the invention can also be used for high throughput broadband transmission.

  Furthermore, the transmission apparatus may include a band pass filter that basically passes only frequency components in the main frequency band, or in the main frequency band and several times as many regions thereof. Thereby, the disturbance stability of radio transmission is further enhanced.

  The listening device according to the invention can be formed as an auditory canal type hearing aid in a special embodiment, even if current consumption and freely available places are extremely limited. . That is, the handset that is typically a magneto-acoustic transducer is very close to the receive coil due to the small amount of space provided. Furthermore, in ear canal type hearing aids, the position and orientation is unique for each device. In any case, the handset induces a more or less large disturbance signal in the receiving coil. At the same time, the signal-to-noise ratio is usually clearly reduced. Although a bad signal-to-noise ratio can be improved by increasing the transmit power, it can only be achieved by a very large energy demand. Therefore, the solution according to the invention of spectrally separating the activation signal for the handset from the transmission signal for wireless data transmission is increasingly advantageous.

  Corresponding to another embodiment, according to the present invention, there is provided a hearing system comprising two hearing aids each having the configuration of the above-described hearing device, wherein the transmission devices of both hearing aids enable two-way wireless transmission. The data transmission in one direction is performed in a different frequency band from the data transmission in the other direction. Thereby, a true bidirectional connection with simultaneous directional transmission can be freely used.

  The present invention will be described in detail with reference to the drawings. The examples described below illustrate advantageous embodiments of the invention.

  In FIG. 2, a schematic of a hearing aid system with two hearing aids 10 and 11 is shown. Both hearing aids 10 and 11 are formed in the same manner. However, only the hearing aid 10 shows essential components for the present invention for the sake of clarity. The central unit of the auditory canal-type hearing aid 10 is a signal processing or control unit 12. It is powered by the battery 13. The output signal of the control unit 12 is used to activate a handset 14, which is typically formed as a magnetoacoustic transducer. Furthermore, the control unit 12 also activates the transmission unit 15, which is used here for bidirectional transmission to the second hearing aid 11. The transmission unit 15 is symbolically indicated by a coil, but can also include other transmission components.

  It can be seen from FIG. 2 that the electronics components in the ear canal hearing aid 10 are placed in close proximity to each other in space. In particular, the handset 14 and the transmission unit 15 are also located very close together, resulting in unintentional mutual influence and interference.

  FIG. 3 shows a typical PDM activation signal which causes the activation unit 12 to activate the handset 14 in time. Information to be transmitted to the handset lurks in the pulse density. FIG. 4 shows an enlarged view of one end of this signal. The density of the impulse varies in the desired manner.

  The handset 14 has a unique inductive characteristic. Therefore, the temporal PDM voltage signal depicted in FIG. 3 results in a current profile drawn in broken lines in the figure at the handset.

  The frequency spectrum of the PDM voltage signal of FIG. 3 is shown in FIG. The spectrum consists essentially of arcuate curves, which are periodically aligned and whose amplitude decreases according to the function sin x / x based on the rectangular shape of the PDM pulse. In a specific region of the spectrum, i.e. between two curves, a notch E, i.e. a so-called "removed region" occurs in the spectrum. In this removed area, no or little interference signal is generated. Only the effective signal N or the effective signal component N ′ is present there. The occurrence of the notch (cut) E can be explained as follows. That is, the pulse duration Tp of the PDM signal is fixedly selected and appears in a fixed time raster of n × Tp. The statistical distribution of positive and negative pulses is the same for natural audio signals. Thereby, the frequency 1 / (2 Tp) and its integer multiple appear at phases 0 ° and 180 ° with substantially the same amplitude. This leads to a targeted loss of the signal in the region around the frequency n × 1 / (2Tp). This disappearance results in the above-described notches or notches E. An arch-shaped interference signal component S is generated between the notches.

  The basic concept of the present invention is to adapt the operating frequency of digital handset operation to a wireless transmission system. Specifically, therefore, an attempt is made to remove the disturbing handset noise component from the frequency band used for the wireless data transmission system. This means that in this case, the operating frequency of the PDM modulator is chosen so that the notch E is in the region of the transmission frequency for radio transmission or several times that frequency, so that the interference spectrum is advantageously adjusted. Achievable by formation (noise shaping). Thereby, the radio transmission is only slightly disturbed and the advantages of digital handset operation are retained.

  Removing the disturbing component from the frequency domain used for wireless data transmission can be supplemented by another known “noise shaping” method. For example, the noise component can be shifted from the low frequency region of the audio signal to higher frequencies in a known manner. By this and other known methods, the width and shape of the previous notches or notches can be optimized.

  The signal processing of the radio transmission component is performed by a band-pass filter that passes unimpeded only the frequencies within the bandwidth used for radio, thereby further improving the jamming stability for radio transmission handset operation. . The filter function F of such a band pass filter is shown in FIG. 6 together with the PDM frequency spectrum of the exemplary signal. Improving the disturbance stability is particularly effective when the characteristics of the bandpass (filter side edge slope, filter goodness) and “noise shaping” characteristics are compatible with each other.

  In the example of FIG. 5, notches occur at fixed frequency intervals. In the simplest case, only one of them is used for wireless data transmission. For applications requiring a large bandwidth, the wireless transmission can be divided into a plurality of partial frequency domains. In that case a partial frequency domain should be present in the other notch of the PDM activation signal for the handset. With regard to the disturbance stability, the bandpass characteristic and the “noise shaping” characteristic should also be matched to each other. This is achieved, for example, by a unique comb filter whose passband is adjusted to a notch.

  After filtering, a flat and low basic noise level is obtained, from which small effective signals can still be detected well. As a result, the reachable range for wireless transmission increases. Instead, higher throughput is achieved for the same reach.

  It has already been suggested above that bandwidth intensive transmission of audio signals or programming data is possible for applications where multiple frequency domains are utilized. In some cases, it is possible to use multiple frequency bands for simultaneous bi-directional transmission by distributing directions to different frequency regions.

It is a principle block diagram of the hearing aid by a prior art. It is a block diagram of the hearing aid system by this invention. FIG. 6 is a diagram of a PDM time signal of a handset voltage. FIG. 4 is a partially enlarged view of the PDM time signal of FIG. 3. FIG. 4 is a diagram of the PDM frequency spectrum of the signal of FIG. FIG. 6 is a diagram illustrating the PDM frequency spectrum of FIG. 5 along with a pass curve of an ideally adapted frequency filter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Hearing aid housing 2 Microphone 3 Signal processing unit 4 Handset 5 Battery 10, 11 Hearing aid 12 Control unit 13 Battery 14 Handset 15 Transmission unit E Notch
N Effective signal N 'Effective signal component S Interfering signal component

Claims (10)

In a listening device (10) comprising a transmission device (15) for wireless data transmission in the main frequency band, a speaker (14) and an actuating device (12) for actuating the speaker (14) by an actuating signal,
A listening device, wherein the frequency spectrum of the actuation signal has a substantial notch region in the main frequency band.   2. A hearing device according to claim 1, wherein the actuation signal of the actuation device (12) is pulse density modulated.   The data transmission by the transmission device (15) is performed in a plurality of frequency bands in a wide band, and the frequency spectrum of the operating signal has a substantial notch region in each region of the frequency band. The listening device described.   4. The transmission device according to claim 1, further comprising a band-pass filter that basically passes only frequency components in the main frequency band or in the main frequency band and several times as many regions thereof. The listening apparatus as described in any one.   The listening device according to claim 1, wherein the listening device is formed as an ear canal insertion type hearing aid.   6. A hearing system comprising two hearing aids (10, 11) each having the configuration of a hearing device according to any one of claims 3 to 5, wherein the transmission device (15) of both hearing aids (10, 11) is a two-way radio. A listening system characterized in that data transmission is possible and data transmission in one direction is performed in a different frequency band from data transmission in the other direction. In a method for operating a listening device (10, 11) by wireless data transmission in the main frequency band and activation by an activation signal of a speaker (14) of the listening device,
A method for operating a listening device, wherein the frequency spectrum of the actuation signal has a substantial notch region (E) in the region of the main frequency band.   The method of claim 7, wherein the actuation signal is pulse density modulated.   9. The method according to claim 7, wherein data transmission is performed in a plurality of frequency bands over a wide band, and the frequency spectrum of the operating signal has a substantial notch region (E) in each region of the frequency band. .   10. A signal for data transmission is filtered by a band pass which basically passes only frequency components in the main frequency band or in the main frequency band and several times as many regions thereof. The method as described in any one of these.

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