EP2654321A1 - Method for operating a hearing aid - Google Patents

Abstract

The method involves determining an operating parameter of a hearing apparatus. The operating parameter is smoothened by a filter. An input value (10) is classified in accordance with association with a set of predetermined classes (12) for the input value of the operating parameter, and a counter assigned to the respective class associated with the input value is increased. The counter with a greatest counter value is determined, and an operating parameter value assigned to the counter is output with the greatest counter value as an output variable of the filter. An independent claim is also included for a hearing apparatus.

Description

The invention relates to a method for operating a hearing device, in which an operating parameter of the hearing device is determined and smoothed by means of a filter. The invention further relates to a hearing device with a signal processing device, wherein at least one operating parameter of the signal processing device is adjustable and can be smoothed by a filter

A hearing device here means any device which can be worn in or on the ear and causes a hearing, in particular a hearing aid, a headset, headphones and the like.

Hearing aids are portable hearing aids that are used to care for the hearing impaired. In order to meet the numerous individual needs, different types of hearing aids such as behind-the-ear hearing aids (BTE), hearing aid with external receiver (RIC: receiver in the canal) and in-the-ear hearing aids (ITE), e.g. Concha hearing aids or canal hearing aids (ITE, CIC). The hearing aids listed by way of example are worn on the outer ear or in the ear canal. In addition, bone conduction hearing aids, implantable or vibrotactile hearing aids are also available on the market. The stimulation of the damaged hearing takes place either mechanically or electrically.

Hearing aids have in principle as essential components an input transducer, an amplifier and an output transducer. The input transducer is usually a sound receiver, z. As a microphone, and / or an electromagnetic receiver, for. B. an induction coil. The output transducer is usually used as an electroacoustic transducer, z. As miniature speaker, or as an electromechanical transducer, z. B. bone conduction, realized. The amplifier is standard integrated into a signal processing unit. This basic structure is in FIG. 1 shown using the example of a behind-the-ear hearing aid. In a hearing aid housing 1 for carrying behind the ear, one or more microphones 2 for receiving the sound from the environment are installed. A signal processing unit 3, which is also integrated in the hearing aid housing 1, processes the microphone signals and amplifies them. The output signal of the signal processing unit 3 is transmitted to a loudspeaker or earpiece 4, which outputs an acoustic signal. The sound is optionally transmitted via a sound tube, which is fixed with an earmold in the ear canal, to the eardrum of the device carrier. The power supply of the hearing device and in particular the signal processing unit 3 is effected by a likewise integrated into the hearing aid housing 1 battery. 5

The signal processing unit has operating parameters that are dependent on the microphone signals. For example, depending on a noise intensity, the intensity of noise filtering is varied or an additional directional microphone of a given strength is activated depending on an acoustic environment.

These operating parameters thus vary in time with the acoustic environment. In order to avoid frequent erratic changes in the parameter values, it is customary to smooth the time profile of the parameter values by means of suitable filters.

An example of this is moving average filters, such as the exponentially weighted moving average. In order to achieve smoothing with such a filter, the data to be smoothed over the entire window width in which the smoothing is to take place must be stored in the memory of the signal processing unit. Under normal operating conditions, for example a sampling rate of 24 kHz and a window width of 3 s, considerable amounts of data therefore accumulate due to the limited storage capacity of conventional sig nal processing devices can quickly lead to capacity problems.

From the US 2010/0232633 A1 For example, a method for recording operating parameters of a hearing device is known in which input data are classified according to their belonging to value ranges. For each input value, a counter assigned to the respective value range is incremented, so that a histogram is obtained which reflects the distribution of the input values.

It is therefore an object of the present invention to provide a method and a device of the type mentioned at the outset which make it possible to smooth out temporally varying operating parameter values of a hearing device with the least possible storage requirement.

This object is achieved by a method having the features of patent claim 1 and by a device having the features of patent claim 8.

In a method according to the invention, for each input value-that is to say each unsmoothed value-this input value is classified in accordance with its membership in a plurality of predetermined classes and an associated counter of the respective class to which the input value belongs is incremented. In the simplest case, the counter value of the counter can be incremented by one, but it is also possible to use other increments, which may vary from step to step. Subsequently, the counter with the largest counter value is determined and an operating parameter value assigned to the counter with the largest counter value is output as the output variable of the filter.

Such a smoothing process comes out compared to algorithms known from the prior art with significantly less memory. Instead of the input data over the whole Having to save window width, only space is required for the counters associated with the respective classes, so that the method is particularly suitable to be used under the relatively limited conditions of hearing devices.

In a first variant of the method, the operating parameter value assigned to the counter with the largest counter value is output as the output variable only if the counter exceeds a predetermined threshold value. Otherwise, the last output operating parameter value is retained as output. The choice of the threshold value essentially determines the window width of the smoothing algorithm.

In this case, it is expedient to set all counters to zero when the threshold value is exceeded by one of the counters after outputting the output variable, so that the smoothing effect is maintained and the memory space is limited.

In the hitherto described embodiment, the method is particularly suitable for smoothing operating parameters of the hearing device, which are already present in discretized form. This may be, for example, the evaluation of the acoustic environment of the hearing device according to several discrete classes (conversation situation, background music and the like).

However, the method is also suitable for the treatment of non-discrete, real-valued operating parameters. In this case, the classes are preferably represented by contiguous intervals over predefined, non-discrete value ranges in order to achieve a discretization in the first step of the method, which enables a particularly memory-efficient processing.

In this case, it is also expedient to scale all counter values by a predetermined factor λ with 0≤λ≤1 before increasing the counter value. Such a scaling limits the growth of the counter values and thus indirectly determines the window width of the smoothing algorithm. Furthermore, the scaling influences the extent to which past values determine the current output of the filter, so that the choice of λ makes it particularly easy to adapt the properties of the filter.
Instead of simply incrementing the counters for each class that can be assigned an input value, as in the first described variant, a more complex way of counting is preferably chosen here. In this case, all counter values are increased by an amount which is dependent on a distance of the input value from a midpoint of the interval corresponding to the respective class.

In other words, an input value in this variant of the method affects not only the counter of the class to which it belongs directly, but also the counters of adjacent classes. This leads to additional smoothing and improves the robustness of the algorithm.

It is particularly expedient for each input value y _{i of} the operating parameter, the counter value v _{j of} a class j of the classes, which is assigned an interval with the center b _j , by (1-λ) max (0,1- (y _i -. b _j |) / σ)), where σ represents a predetermined radius of influence.

Classes whose interval center point is further from the input value than the absolute value of σ are therefore not affected, so that the choice of σ can be used to set the smoothing properties of the filter.

Overall, an algorithm is thus created which, with a constant low memory requirement, can discretize over any width of window as well as non-discrete, smoothing real-world data while being resilient to outliers and transient events.

The invention further relates to a hearing device of the type mentioned above, whose signal processing device is designed to classify the input value according to its membership in a plurality of predetermined classes for smoothing the operating parameter for each input value and a counter associated with the respective class to which the input value belongs to increase, to determine the counter with the largest counter value and output an operating parameter value associated with the counter with the largest counter value as the output size of the filter. As already explained with reference to the method according to the invention, a robust and memory-efficient smoothing of the operating parameters of the hearing device can be achieved in this way.

FIG 1

den schematischen Aufbau einer Hörvorrichtung gemäß dem Stand der Technik und

FIG 2

eine schematische Darstellung des Ablaufs eines Ausführungsbeispiels eines Erfindungsgemäßen Verfahrens;

In the following the invention and its embodiments will be explained in more detail with reference to the drawing. Show it:

FIG. 1

the schematic structure of a hearing device according to the prior art and

FIG. 2

a schematic representation of the sequence of an embodiment of a method according to the invention;

To achieve optimal output for the user, hearing devices must be adapted to the particular acoustic environment in which they are used. For this purpose, different operating parameters of the hearing device can be adjusted depending on the environmental conditions. For example, the strength of a noise filtering can be changed, additional directional microphones with different sensitivity can be switched on and the like.

The operating parameters are determined in dependence on an acoustic input signal of the hearing device. ever Depending on the type of acoustic event, it can lead to strong, sudden fluctuations in the operating parameters, which affect hearing comfort. For this reason, it is necessary to smooth the timing of these operating parameters.

However, prior art smoothing methods, such as exponentially weighted moving averaging, require large amounts of memory space because the entire smoothing input data must be held in memory throughout the window width of the smoothing algorithm, quickly leveraging the limited resources of signal processing device 3 can.

A much lower memory usage can be achieved by the in FIG. 2 schematically illustrated embodiment of a method according to the invention can be achieved.

Input data 10 for the smoothing filter are classified according to their membership in a plurality of classes 12. If an input value 10 falls in one of the classes 12, a counter associated with class 12 is incremented. If one of the counters exceeds a predetermined threshold value 14, the output value of the filter is output as output value assigned to the class 12 belonging to the counter and all counters are reset to zero. Otherwise, the previous output value is retained.

The signal processing device 3 therefore only has to provide storage space for the counters of the classes 12. The storage space requirement is independent of the window width, which is determined by the choice of the threshold value 14. At the same time, the algorithm is robust against outliers and transient events and thus enables a reliable smoothing of already discretized input values 10.

If real-valued, non-discrete input quantities are to be smoothed, this can be done in FIG. 2 refines schematically shown method become. For a sequence y ₀ , y ₁ ,..., Y _i of input values, a discretization is first carried out. Each y _i is assigned to an interval j with the center b _j . For each interval j there also exists a counter v _j , which is initialized to an initial value, preferably zero, at the beginning of the method.

For each new input value y _i , which the filter receives, first all counters v _j are scaled by multiplication by a factor λ with 0≤λ≤1. This limits the growth of the counter values, so that here no zeroing of the counters v _{j has} to take place at predetermined intervals. Furthermore, the scaling determines how heavily input-processed input values y _i affect the current output values of the filter. The average lifetime of the counter values is λ ^-1 due to the scaling, which can be considered as the window width of the filter.

After scaling, the counters v _{j are} modified in dependence on the current input value y _i . This is done according to the function v _j → λ v _j + (1-λ) max (0; 1- (| y _i -b _j |) / σ). σ represents an influence radius.
For a given input value y _i , therefore, all counters v _{j associated} with an interval j whose center b _{j is} less than σ away from the input value y _{i are} increased in proportion to the distance between y _i and b _j . This leads to an additional smoothing of the filter output and improves the robustness of the filter.

After increasing the counter _j v _j v of the largest counter value is finally determined and output as the output value of the filter, the center b of the _j counter this v _j associated interval j. Then the next input value y _{i can be} processed.

The described method exhibits a smoothing behavior similar to that of the exponentially weighted moving average strongly resembles. With higher robustness against outliers, however, much less space is needed.

It is also possible to use negative values as output values of the counters v _j , and to change the output value of the filter only if one of the counters v _j reaches or exceeds zero. In this way it can be ensured that no change in the output value takes place over predeterminable time segments in order to achieve a particularly smooth output.

Claims (8)

Method for operating a hearing device, in which an operating parameter of the hearing device is determined and smoothed by means of a filter,
characterized in that
Smoothing includes the following steps: a) for each input value: classifying the input value according to its belonging to a plurality of predetermined classes and incrementing one of the respective class to which the input value belongs associated counter; b) determining the counter with the largest counter value; c) outputting an operating parameter value assigned to the counter with the largest counter value as the output variable of the filter. Method according to claim 1,
characterized in that, in step c), only the operating parameter value assigned to the counter with the largest counter value is output as output variable if the counter value exceeds a predetermined threshold value and otherwise the last output operating parameter value is retained as the output variable. Method according to claim 2,
characterized in that when the threshold value is exceeded by one of the counter values in step c) after outputting the output quantity, all counter values are set to zero. Method according to claim 1,
characterized in that each of the classes is each a contiguous interval over a predetermined non-discrete value range. Method according to claim 4,
characterized in that prior to increasing the counter value in step a) all counter values are scaled by a predetermined factor λ with 0≤λ≤1. Method according to claim 5,
characterized in that in step a) all counter values are increased by an amount which is dependent on a distance of the input value from a mid-point of the interval corresponding to the respective class. Method according to claim 6,
characterized in that
for each input value y _{i of} the operating parameter, the counters v _{j of} a class j of the classes to which an interval having the center b _{j is} assigned by (1-λ) max (0,1- (y _i -b _j |) / σ )), where σ represents a given radius of influence. Hearing apparatus with a signal processing device (3) including a filter, wherein at least one operating parameter of the signal processing device (3) is adjustable and can be smoothed by the filter,
characterized in that
the signal processing device (3) is arranged to classify the input value according to its membership in a plurality of predetermined classes for smoothing the operating parameter for each input value and to increase a counter associated with the respective class to which the input value belongs, the counter with the largest one To determine counter value and output the counter with the largest counter value associated operating parameter value as the output size of the filter.

Images