Method for extending a frequency range of an input signal of a hearing device as well as a hearing device
View Patent ↗The present invention is directed to a method and a hearing device for extending a usable frequency range of an analog input signal (i) being processed by a hearing device, the method comprising the steps of converting the analog input signal (i) to a first output signal (o 1 ) and to an intermediate signal (o m ), the first output signal (o 1 ) having a final sampling rate and the intermediate signal (o m ) having an intermediate sampling rate that is greater than the final sampling rate, applying a band-pass filter unit ( 31 ) to the intermediate signal (o m ) in order to obtain a filtered intermediate signal (o mf ), a lower cut-off frequency of the band-pass filter unit ( 31 ) being above half the final sampling rate, an upper cut-off frequency of the band-pass filter unit ( 31 ) being below half the intermediate sampling rate, and shifting a spectrum of the filtered intermediate signal (o mf ) to a frequency range being below the final sampling rate to obtain an intermediate output signal (o m2 ).
1. A method for extending a usable frequency range of an analog input signal (i) being processed by a hearing device, the method comprising the steps of:
converting the analog input signal (i) to a first digitized output signal (o 1 ) and to an intermediate signal (o m ), the first output signal (o 1 ) having a final sampling rate and the intermediate signal (o m ) having an intermediate sampling rate that is greater than the final sampling rate,
applying band-pass filtering to the intermediate signal (o m ) in order to obtain a filtered intermediate signal (o mf ), a lower cut-off frequency of the band-pass filtering being above half the final sampling rate, an upper cut-off frequency of the band-pass filtering being below half the intermediate sampling rate, and
shifting a spectrum of the filtered intermediate signal (o mf ) to a frequency range being below the final sampling rate to obtain an intermediate output signal (o m2 ).
2. The method of claim 1 , further comprising the step of decimating the intermediate output signal (o m2 ) having the intermediate sampling rate to the final sampling rate to obtain a second output signal (o 2 ).
3. The method of claim 2 , further comprising the step of processing the first output signal (o 1 ) and the second output signal (o 2 ) in the hearing device.
4. The method of claim 1 , wherein the step of converting the analog input signal (i) is performed by at least two decimation stages ( 22 , 23 , 24 ).
5. The method of claim 1 , wherein the spectrum of the filtered intermediate signal (o mf ) is shifted to a frequency range lying below half the final sampling rate.
6. The method of claim 1 , wherein the intermediate sampling rate is an even integer multiple higher than the final sampling rate.
7. The method of claim 6 , wherein the intermediate sampling rate is four times higher than the final sampling rate.
8. The method of claim 1 , further comprising the step of processing the first output signal (o 1 ) and the intermediate output signal (o m2 ) in the hearing device.
9. A hearing device comprising:
an input transducer ( 1 ) for generating an analog input signal (i),
an analog-to-digital converter ( 2 ) for converting the analog input signal (i) to a first output signal (o 1 ) and to an intermediate signal (o m ), the first output signal (o 1 ) having a final sampling rate and the intermediate signal (o m ) having an intermediate sampling rate that is greater than the final sampling rate,
a band-pass filter ( 31 ) for processing the intermediate signal (o m ) in order to obtain a filtered intermediate signal (o mf ), a lower cut-off frequency of the band-pass filter ( 31 ) being above half the final sampling rate, an upper cut-off frequency of the band-pass filter ( 31 ) being below half the intermediate sampling rate, and
means for shifting a spectrum of the filtered intermediate signal (o mf ) to a frequency range being below the final sampling rate to obtain an intermediate output signal (o m2 ).
10. The hearing device of claim 9 , further comprising a decimation unit ( 34 ) for decimating the intermediate signal (o m ) having the intermediate sampling rate to the final sampling rate to obtain a second output signal (o 2 ).
11. The hearing device of claim 10 , further comprising a signal processing unit ( 3 ) for processing the first output signal (o 1 ) and the second output signal (o 2 ).
12. The hearing device of claim 9 , wherein the analog-to-digital converter ( 2 ) comprises at least two decimation stages ( 22 , 23 , 24 ).
13. The hearing device of claim 9 , wherein the spectrum of the filtered intermediate signal (o mf ) is shifted to a frequency range lying below half the final sampling rate.
14. The hearing device of claim 9 , wherein the intermediate sampling rate is an even integer multiple higher than the final sampling rate.
15. The hearing device of claim 14 , wherein the intermediate sampling rate is four times higher than the final sampling rate.
16. The hearing device of claim 9 , further comprising a signal processing unit ( 3 ) for processing the first output signal (o 1 ) and the intermediate output signal (o m2 ).