Method, device, and system for suppressing feedback in hearing aid devices with adaptive split-band frequency
First Claim
1. A method for suppressing acoustic feedback in a hearing aid device, wherein the hearing aid device has an acoustoelectric input transducer, a signal processing device, and an electroacoustic output transducer, the method comprising:
- dividing an acoustic frequency range transmitted by the hearing aid device into a first frequency range above a first split-band frequency and a second frequency range below the first split-band frequency;
estimating a first transfer function mapping a real transfer function of a feedback loop via the electroacoustic output transducer, an acoustic feedback path, the acoustoelectric input transducer and the signal processing device in the first frequency range;
assessing the first transfer function to determine whether to expect the real transfer function to exceed a limit value from a behavior of the first transfer function in an environment of the first split-band frequency;
if the real transfer function is not expected to exceed the limit value in the environment of the first split-band frequency, increasing the first split-band frequency to a second split-band frequency, so that all values of a gain of the first transfer function for frequencies less than the increased second split-band frequency are less than the predetermined limit value;
orif the real transfer function is expected to exceed the limit value in the environment of the first split-band frequency, reducing the first split-band frequency to a second split-band frequency; and
applying a phase or frequency change for feedback suppression in the signal processing only above an inception frequency in dependence on the second split-band frequency.
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Abstract
A method for suppressing acoustic feedback in a hearing aid device and a corresponding device and a system. A frequency range to be transmitted by the hearing aid device is divided into two frequency ranges that are separated by a split-band frequency. A transfer function of a feedback path is estimated in a frequency range and assessed for its behavior at the split-band frequency. Depending on the result of the assessment, the split-band frequency is lowered or raised and in the upper frequency range a phase and/or frequency change is applied for suppressing feedback.
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Citations
19 Claims
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1. A method for suppressing acoustic feedback in a hearing aid device, wherein the hearing aid device has an acoustoelectric input transducer, a signal processing device, and an electroacoustic output transducer, the method comprising:
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dividing an acoustic frequency range transmitted by the hearing aid device into a first frequency range above a first split-band frequency and a second frequency range below the first split-band frequency; estimating a first transfer function mapping a real transfer function of a feedback loop via the electroacoustic output transducer, an acoustic feedback path, the acoustoelectric input transducer and the signal processing device in the first frequency range; assessing the first transfer function to determine whether to expect the real transfer function to exceed a limit value from a behavior of the first transfer function in an environment of the first split-band frequency; if the real transfer function is not expected to exceed the limit value in the environment of the first split-band frequency, increasing the first split-band frequency to a second split-band frequency, so that all values of a gain of the first transfer function for frequencies less than the increased second split-band frequency are less than the predetermined limit value;
orif the real transfer function is expected to exceed the limit value in the environment of the first split-band frequency, reducing the first split-band frequency to a second split-band frequency; and applying a phase or frequency change for feedback suppression in the signal processing only above an inception frequency in dependence on the second split-band frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 18)
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8. A device for suppressing acoustic feedback in a hearing aid device, the hearing aid device having an acoustoelectric input transducer, a signal processing device, and an electroacoustic output transducer, the device for suppressing acoustic feedback comprising:
- a signal connection to the hearing aid device;
a processing device configured to;
divide an acoustic frequency range to be transmitted by the hearing aid device into a first frequency range above a first split-band frequency and a second frequency range below the first split-band frequency;
estimate a first transfer function as mapping of a real transfer function of a feedback loop via the electroacoustic output transducer, an acoustic feedback path, the acoustoelectric input transducer, and the signal processing device in the first frequency range;
assess the first transfer function to determine whether to expect the real transfer function to exceed a limit value from a behavior of the first transfer function in an environment of the first split-band frequency;
if the real transfer function is not expected to exceed the limit value in the environment of the first split-band frequency, increase the first split-band frequency to a second split-band frequency by such an amount that all the values of a gain of the first transfer function for frequencies less than the second split-band frequency are less than the predetermined limit value;
or if the real transfer function is expected to exceed the limit value in the environment of the first split-band frequency, reduce the first split-band frequency to a second split-band frequency; and
adjust in the hearing aid device a phase or frequency change for feedback suppression in the signal processing device only above an inception frequency in dependence on the second split-band frequency. - View Dependent Claims (9, 10, 11, 12, 13, 14, 19)
- a signal connection to the hearing aid device;
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15. A hearing aid device with acoustic feedback suppression, comprising:
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an acoustoelectric input transducer, a signal processing device connected to said input transducer, and an electroacoustic output transducer connected to said signal processing device; a device for suppressing acoustic feedback connected, by way of a signal connection, to said signal processing device, and being configured to carry the following method steps; dividing an acoustic frequency range transmitted by the hearing aid device into a first frequency range above a first split-band frequency and a second frequency range below the first split-band frequency; estimating a first transfer function mapping a real transfer function of a feedback loop via the electroacoustic output transducer, an acoustic feedback path, the acoustoelectric input transducer and the signal processing device in the first frequency range; assessing the first transfer function to determine whether to expect the real transfer function to exceed a limit value from a behavior of the first transfer function in an environment of the first split-band frequency; if the real transfer function is not expected to exceed the limit value in the environment of the first split-band frequency, increasing the first split-band frequency to a second split-band frequency, so that all values of a gain of the first transfer function for frequencies less than the increased second split-band frequency are less than the predetermined limit value;
orif the real transfer function is expected to exceed the limit value in the environment of the first split-band frequency, reducing the first split-band frequency to a second split-band frequency; and applying a phase or frequency change for feedback suppression in the signal processing only above an inception frequency in dependence on the second split-band frequency. - View Dependent Claims (16, 17)
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Specification