EP0723381B1 - Device for hearing assistance - Google Patents

Abstract

The device has two microphones (2,3) coupled to a control unit (1). The microphones (2,3) supply the control unit (1) with input signals. The control element (1) transmits at least one output signal to at least one transmission element (8). The control unit (1) is spatially separated from the microphones (2,3). Each microphone (2,3) is held in an ear housing (4,5) which can be arranged near the ear (22). Each housing (4,5) has a transmitter (6) which communicates with a receiver (7) near the control unit (1). A transmitter element (8) is arranged near at least one of the housings (4,5) and has a receiver (9). This communicates with a transmitter (10) near the control unit (1). A comparator (12) analyses the microphone signals and modifies the output power of the control unit (1) to adapt to a spatial sound reproduction.

Description

The invention relates to a device for hearing support, which has two microphones, which are coupled to a control unit and feed the control unit with input signals and in which the control unit transmits at least one output signal to at least one transmission element and in which the control unit is arranged spatially separate from the microphones , and in which the microphones are accommodated in ear housings which can be arranged in the region of a human ear and in which the ear housings are each provided with a transmitter which communicates with a receiver in the region of the control unit, and in which at least one of the ear housings has one of the transmission elements is arranged, which is provided with a receiver which communicates with a transmitter in the area of the control unit and in which an analyzer is arranged in the area of the control unit for evaluating the signals of the microphones.

From FR-A-2 651 634 a device for hearing support is already known, in which a microphone is coupled to a control unit and in which the control unit is arranged spatially separate from the microphone. The microphone is arranged in the area of an ear housing that can be picked up by a human ear. Communication takes place via a receiver and a transmitter and is in the area of the control unit an analyzer for evaluating the signals of the microphone is arranged.

DE-A-2 406 218 describes a device for hearing support in which two microphones are already used. However, both microphones are arranged in a common ear housing. At least one of the microphones has a directional characteristic. The signals from the two microphones are processed in the area of a control unit.

Another device for hearing support is known from WO-A-89 04 583. According to this document, a microphone is arranged in the area of an ear housing, which communicates with a spatially separated control unit via a transmitter and a receiver.

A comparable device is known from DE-OS 35 12 999. A different orientation of the microphones and a subsequent subtraction of the output signals of the microphones from one another should make it possible to eliminate ambient noise that is effective in all listening directions. The transmission element is designed here as a loudspeaker.

From DE-OS 35 08 830 it is known, locally separated from a loudspeaker, which is arranged in an ear housing, which in turn can be picked up by a human ear or can be arranged behind a human ear, in the area of a separate control unit, a microphone, a To arrange amplifiers and a power source. This device makes it possible to construct the component to be arranged in the region of the human ear relatively easily. A wireless transmission of signals to a hearing aid is described in DE-OS 30 32 311. In this case, signals to be transmitted wirelessly are provided, which are provided, for example, by a telecommunications system or a radio. Another construction, in which a spatial separation of loudspeaker and control unit is provided, is described in DE-OS 28 44 979. Here, too, the microphone is arranged in the area of the control unit.

From DE 31 00 135 C2 a device for hearing support is already known which has two microphones which are coupled to a control unit. The microphones feed the control unit with input signals. The control unit transmits at least one output signal to at least one transmission element. The control unit is spatially separated from the microphones and each of the microphones is accommodated in a housing. One of the transmission elements is arranged in the area of an ear housing. A comparator for evaluating the signals of the microphones is provided in the area of the control unit, which modifies the output power of the control unit to adapt to a sound reproduction.

DE 30 27 384 describes a method for reshaping sound signals in which unnatural directional sensations can be converted into more natural hearing sensations by reshaping the directional impressions in the natural hearing sensations.

DE 41 01 933 A 1 describes a control unit for directional microphone signals for generating virtual directional characteristics with an adjustable main reception direction. The output signal is multiplied by Evaluation of the input signals with control parameters formed.

From DE 35 30 205 Al, a microphone system with a variable directional characteristic is already known, which has a series of microphones which are arranged at the same distance from one another. The directional characteristic is realized by a special row-like arrangement of the microphones and by using a weighting network with weighting factors.

DE 29 28 845 A1 describes an audiovocal integration device which has a microphone which is coupled via a special device to a vibrator which can apply vibrations to the skin of a user. The acoustic as well as the sensitive signal transmission is coordinated via a corresponding control.

According to this prior art, either devices for hearing support are known in which all components are arranged in the area of the human ear, or in which only one loudspeaker is provided in the case of spatial separation of components in the area of the ear and the other components, in particular the Amplifiers and the microphones are provided in the area of a control unit arranged spatially separate from the loudspeaker. With these devices, it is not possible in a satisfactory manner to enable a user to have a spatial hearing modeled on the natural hearing sensation and at the same time to suppress interference noises.

The object of the present invention is to provide a device of the type mentioned in the introduction construct that both a good acoustic quality is guaranteed and a user experience perceived as pleasant is realized.

This object is achieved in that the analyzer modifies the output power of the control unit to adapt to a spatial sound reproduction, that the output signals of the microphones are evaluated by the analyzer and that an ear amplifier is arranged in the area of at least one of the transmission elements.

With the aid of the arrangement of the microphones within the earhousings, the sound reception is aligned in different directions in accordance with customary listening habits. In particular, this makes it possible to compensate for noise by targeted directional hearing. It is possible to carry out a central evaluation of the signals from the individual microphones.

With the aid of the comparator, for example, a useful sound / interference sound selection method can be carried out which, if there is hearing impairment, enables the person concerned to predominantly perceive a sound source which is considered to be dominant by moving the head or making a corresponding setting in the area of the control unit. It does not matter whether the acoustic signals are speech, music or typical background noises. In particular, it is possible to simulate a hearing sensation in a mono-aurally treated hearing impairment that largely corresponds to normal spatial hearing. This results from the fact that the hearing impaired by a movement of his head and by the corresponding signal evaluation can locate a sound source.

The arrangement of the microphones in ear housings, which can be inserted into the ear and the shifting of all other elements into the area of the spatially separated control unit, creates an optically barely perceptible hearing aid that, with high sound quality, does not limit the appearance of the sound Device equipped people.

A particularly high level of user convenience is provided in that a transmission path is provided for data transmission from the transmitters to the receivers. This can be wireless.

To ensure a high level of transmission security, it is also possible for the transmitters to be connected to the receivers via a line.

To support directional hearing, it is proposed that the comparator be provided with an envelope correlator.

Directional hearing can also be improved further by providing the comparator with a time correlator.

An ergonomically particularly expedient arrangement of the control unit takes place in that the control unit is arranged in the region of a bracelet that can be worn on a wrist.

To enable manual parameter specifications, it is proposed that the control unit for manual inputs have an operating unit.

Another variation for directional listening is provided in that a directional microphone is arranged in the area of the control unit.

To supply power to the ear amplifier and other components, an ear battery is arranged in the area of at least one of the ear housings.

To avoid inappropriate volume levels, it is proposed that a level limiter be provided in the area of the control unit for at least one transmission channel.

A sufficient intensity of the signals emitted by the control unit can take place in that a main amplifier is provided in the area of the control unit.

Adequate sound energy in the area of the earhousing is provided in that an ear amplifier is arranged in the area of at least one of the transmission elements.

Fig. 1

ein Blockschaltbild mit einer Anordnung mit zwei Mikrofonen sowie örtlich getrennt angeordneter Steuereinheit, bei der die übertragung leitungsgebunden erfolgt,

Fig. 2

eine vergrößerte Darstellung der Steuereinheit gemäß Fig. 1,

Fig. 3

eine Prinzipdarstellung zur Veranschaulichung eines räumlichen Hörvorganges,

Fig. 4

eine im Bereich eines Armbandes angeordnete Steuereinheit,

Fig. 5

eine Prinzipdarstellung zur Veranschaulichung einer Hüllkurvenkorrelation und

Fig. 6

eine Prinzipdarstellung zur Veranschaulichung einer Zeitkorrelation.

Exemplary embodiments of the invention are shown schematically in the drawing. Show it:

Fig. 1

2 shows a block diagram with an arrangement with two microphones and a control unit which is arranged at a separate location and in which the transmission takes place in a line-bound manner,

Fig. 2

2 shows an enlarged illustration of the control unit according to FIG. 1,

Fig. 3

a schematic diagram to illustrate a spatial hearing process,

Fig. 4

a control unit arranged in the area of a bracelet,

Fig. 5

a schematic diagram to illustrate an envelope correlation and

Fig. 6

a schematic diagram to illustrate a time correlation.

According to the embodiment in FIG. 1, the device for hearing support consists of a control unit (1), two microphones (2, 3) and earhouses (4, 5) in which the microphones (2, 3) are installed and which have a shape which makes it possible to arrange the ear housings (4, 5) in the area of an ear cup or an auditory canal of a human ear. Each of the microphones (2, 3) is assigned a transmitter (6) in the area of the ear housings (4, 5), which communicates with a respective receiver (7) in the area of the control unit (1). According to the embodiment in FIG. 1, a transmission element (8) is additionally arranged in the area of each of the earhouses (4, 5), which is connected to a receiver (9) likewise arranged in the area of the earhousing (4, 5). The receivers (9) receive their signals from transmitters (10) which are arranged in the area of the control unit (1). For the immediate supply of the transmission elements (8), ear amplifiers (11) are arranged in the area of the ear housing (4, 5).

The control unit (1) is provided with a comparator (12), which enables the signals from the microphones (2, 3) to be evaluated relative to one another in order to simulate spatial hearing and to suppress noise. If the transmission elements (8) are designed as loudspeakers, level limiters (13) are provided in the control unit (1) in order to limit the sound energy emitted in the region of the loudspeakers. The control unit (1) has a main battery (14) for the energy supply. The ear housings (4, 5) can be provided with ear batteries (15) for supplying energy to the components. The transmission elements (8) can also be designed as electrodes which act electrically on the auditory nerves.

The detailed structure of the control unit (1) is shown in FIG. 2. The overall function is monitored by a controller (16). In addition to the already mentioned level limiters (13), the comparator (12), the main battery (14) and the receivers (7) and the transmitters (10), a service unit (17) and a display (18) are further modules Directional microphone (19) and a frequency filter (20) are provided. Level adjustment takes place via a main amplifier (34). When selecting a sound pattern, predefined tables can be accessed via the controller (16), by means of which the frequency filter (20) and the level limiter (13) can be set.

A schematic diagram to illustrate spatial hearing is shown in FIG. 3. An individual (21) has his ears (22) aligned in a listening direction (23). In the case of side sound radiation (24), a sound pulse strikes the ears (22) at different times. Sound pressure profiles (25) thus have a time in the area of the ears (22) offset course and different levels. In the case of frontal sound radiation (26), however, the sound pressure profiles (25) in the area of the ears (22) are essentially congruent in time.

According to the embodiment in FIG. 4, it is particularly contemplated to arrange the control unit (1) in the area of a bracelet (27), which in turn can be fastened in the area of a human wrist (28). If space is restricted, it is also possible to mount some of the components of the control unit (1) in the area of links of the bracelet (27).

In order to clarify the functioning of the comparator (12), a circuit variant for an envelope correlation is shown in FIG. 5 and a circuit variant for a time correlation is shown in FIG. 6. 5, the microphones (2, 3) are each connected to a frequency separator (29). The frequency separator (29) has separate outputs (30) assigned to individual frequency ranges. For example, it is possible to assign a separator output to the frequency range from 0 to 0.5 kHz, the next separator output (30) to the frequency range from 0.5 to 1 kHz and the further frequency ranges to additional separator outputs (30). Envelope correlators (31) are used to analyze sound pressure level differences between the microphones (2, 3). If such a sound pressure level difference occurs in one of the frequency ranges, only the weaker signal component is added to the overall signal. This takes advantage of the fact that laterally incident sound waves reach the ear facing away from the sound source or the associated microphone (2, 3) with a level difference and a time difference. In principle it is It is useful to use both the level difference according to the variant in FIG. 5 and the time difference according to the variant in FIG. 6.

6, a time correlator (32) is used and a coupling takes place according to a bypass via attenuators (33).

Both the envelope correlation and the time correlation can be implemented in analog or digital circuitry. In particular, it is contemplated that a combination of the two methods can improve sound detection. To ensure sufficient recognition of loudness differences between the left and right ear, it is advisable to activate the correlation method only when there is frontal sound radiation (26).

With the help of the control unit (1) carried in the area of the wrist (28), it is possible to change the settings made without changing the position of the microphones (2, 3). This means that the ear housings (4, 5) arranged inside the ears (22) need not be accessed. The directional microphone (19) can be positioned by a corresponding movement of a forearm of the individual (21).

External audio inputs and audio outputs can also be implemented. With the help of these additional devices, it is possible to generate, send, receive and listen to warning signals or telephone signals.

The operating unit (17) in the area of the control unit (1) makes it possible to carry out a predefinable amplification of signals from one of the microphones (2, 3). This allows the user to avoid turning his head in the direction of the desired sound source. It is also possible to use the control unit (17) to adjust the volume, select a microphone or specify a sound group program.

In the case of a wired coupling between the earhouses (4, 5) and the control unit (1), the transmitters (6, 10) are implemented, for example, as output amplifiers and the receivers (7, 9) as input amplifiers. With a wireless connection, standardized and therefore inexpensive radio elements can be used. In the case of a radio connection, for example, certain transmission frequencies can be reserved to suppress interference, and it is also possible to provide alternative transmission channels or to provide alternative modulation frequencies. Wireless transmission can also take place via IR or HF signals.

The device can be used for various applications. When using the device as a hearing aid already described, it is possible to record the sound via the microphones (2, 3) in the area of the ear housing (4, 5). Alternatively, it is possible to record sound using a microphone arranged in the area of the bracelet (27). Further sound recordings can be made externally, for example via a telephone, a radio, a surveillance microphone, consumer electronics devices, personal computers or alarm detectors.

When used as a hearing aid, the signal processing takes place in the area of the central unit, which can have the comparator (12), the level limiter (13), the frequency filter (20) and a corresponding amplifier (34). The comparison of the time and level difference between the spectral components of the left and right microphone signals optionally leads to noise suppression. The signal components with time and level difference are not amplified. A user of the device is thus able to primarily perceive the sound source to which he is turning the front of his head.

If the microphones (2, 3) are arranged inside the auricles, the signals coming from behind are attenuated by the auricle. If the comparator (12) recognizes that signals with time and level differences are almost exclusively present, no noise suppression is carried out. This happens, for example, when a conversation partner sits and talks on the left or right side of the user and a conversation partner sitting opposite is silent. Noise suppression is not carried out when recording sound via the microphone arranged in the area of the bracelet (27) or when recording sound from external audio units.

In the case of a wired connection between the central unit and the components within the ear housing (4, 5), no amplifier and no power supply are required in the area of the ear housing (4, 5). If necessary, however, a preamplifier can be useful for transmission. When used as a hearing aid, sound is reproduced via at least one of the loudspeakers in the area of the ear housing (4, 5). Is the side sound suppression with an inner ear implant used, the side-noise-suppressed signal is fed to the processor that controls the implanted electrodes. The electrodes stimulate the auditory nerves.

For applications outside the area of use of hearing aids, sound is recorded via a microphone in the area of the central unit. The signal processing in the area of the central unit can optionally be used to suppress noise. The sound is reproduced externally, for example via the same device, a telephone, a radio, a personal computer or an alarm detector.

It is also possible to provide external sound recording in such applications. This can be done, for example, via a telephone, a radio, a security microphone, a consumer electronics device, a personal computer or an alarm detector. The signal processing in the central unit can optionally also be equipped with speech recognition or speech generation. In the case of external sound recording, sound is reproduced via at least one loudspeaker in an ear housing (4, 5). It is also conceivable to carry out the sound reproduction via a loudspeaker in the area of the central unit.

The signal transmission between the microphones (2, 3) in the area of the ear housing (4, 5) and the central unit can take place both analog and digital. It is also possible to implement signal processing in analog or digital form. Mixed analog and digital processing is also possible depending on the respective boundary conditions. Analog-to-digital conversions are made in accordance with the processing sequence selected in each case or digital-analog conversions performed. In the case of a partial analog design, particular consideration is given to performing amplification operations analog.

To carry out digital signal processing, the signals picked up by the microphones (2, 3) are digitized and broken down into individual frequency bands. As a result, the individual spectral components are available for further evaluation. The breakdown can be done, for example, by Fast Fourier Transformations (FFT) or by using filter banks. After the separation into the frequency bands has been carried out, it is possible to carry out side noise suppression, frequency response correction, dynamic compression, dehumidification or other methods for improving speech intelligibility.

In the case of a frequency response correction, the necessary dynamic corrections are carried out for the individual frequency ranges in accordance with an existing hearing impairment. It is advisable not to exceed a maximum value to ensure sufficient hearing comfort.

Dynamic compression takes into account the fact that a dynamic range for normal hearing is within 0 dB to 130 dB. If there is hearing impairment, noises are only perceived from a certain threshold value of the volume. This is also frequency dependent. The dynamic range is limited. If, for example, a linear amplification of all noises is carried out, then amplitudes above the discomfort threshold, for example above a limit value of 130 dB, would have to be cut off. It is therefore cheaper to use the amplitude curve maintain and compress the limited dynamic range.

In connection with the dehalling, it is also possible to provide an anti-feedback. If the signal is digitized, it can be determined whether there are reverberation influences and the reverberation effect can be minimized. Digitization enables the signals to be assessed. In addition, it can be determined whether additional amplification of the already amplified signals has been carried out by the amplifier. A time delay of the signal makes it possible to suppress feedback effects that may occur.

The improvement of speech intelligibility can be carried out by special algorithms that lead to an increase in speech sharpness.

All of the measures described above for influencing the signal can be formulated as algorithms for processing with a digital computer. It is advisable to assign the algorithms to a specific spectral component in order to increase or decrease the dynamic value. After appropriate splitting of the signal into the spectral components and application of the algorithms described, a recombination takes place to form a resulting overall signal. This can be done for example by inverse Fast Fourier Transformation or an inverse filtering corresponding to the initial filtering.

As an alternative to a complete digital implementation of the algorithms, it is also possible to implement a partially analog implementation. Especially for frequency response correction and Dynamic compression can have advantages by using analog techniques. As an alternative to the analog implementation of envelope and time correlator described above, however, digital algorithms are preferably used. This results in stair curves as the envelope.

Claims (11)

1. A device for hearing assistance, which comprises two microphones (2, 3), which are coupled to a control unit and supply the control unit (1) with input signals and in which the control unit (1) transmits at least one output signal to at least one transmission element and in which the control unit (1) is arranged spatially separate from the microphones (2, 3), and in which the microphones (2, 3) are accommodated in ear housings (4, 5) which can be arranged in the region of a human ear (22) and which are each provided with a transmitter (6), which communicates with a receiver (7) in the region of the control unit (1), and in which one of the transmission elements (8) is arranged in the region of at least one of the ear housings (4, 5), the transmission element (8) being provided with a receiver (9), which communicates with a transmitter (10) in the region of the control unit (1) and in which an analyser (12) for evaluating the signals of the microphones (2, 3) is arranged in the region of the control unit (1), characterised in that the analyser (12) modifies the output power of the control unit (1) for adaptation to three-dimensional sound reproduction, output signals of the microphone (2, 3) are evaluated by being compared by the analyser (12), and an ear amplifier (11) is arranged in the region of at least one of the transmission elements (8).
2. A device according to claim 1, characterised in that a transmission path is provided for data transmission from the transmitters (6, 10) to the receivers (7, 9).
3. A device according to claim 1, characterised in that the transmitters (6, 10) are connected to the receivers (7, 9) via a line.
4. A device according to one of claims 1 to 3,
   characterised in that the analyser (12) is provided with an envelope curve correlator (31).
5. A device according to one of claims 1 to 4,
   characterised in that the analyser (12) is provided with a time correlator (32).
6. A device according to one of claims 1 to 5,
   characterised in that the control unit (1) is arranged in the region of an arm band (27) which can be worn on a wrist (28).
7. A device according to one of claims 1 to 6,
   characterised in that the control unit (1) comprises an operating unit (17) for manual input.
8. A device according to one of claims 1 to 7,
   characterised in that a directional microphone (19) is arranged in the region of the control unit (1).
9. A device according to one of claims 1 to 8,
   characterised in that a level limiter (13) is provided in the region of the control unit (1) for at least one transmission channel.
10. A device according to one of claims 1 to 9,
    characterised in that a main amplifier (43) is provided in the region of the control unit (1).
11. A device according to one of claims 1 to 10,
    characterised in that an ear battery (15) is arranged in the region of at least one of the ear housings (4, 5).

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