# US 2019/0379985 A1 · Hearing device comprising adaptive sound source frequency lowering

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 2019/0379985 A1
- Document ID: US20190379985A1
- Status: Published application
- Kind: A1
- Application number: 16/437,634
- Filed: 2019-06-11
- Published: 2019-12-12
- Earliest claimed: 2018-06-12
- Assignees: Oticon A/S
- Applicants: Oticon A/S
- Inventors: Anders Højsgaard THOMSEN; Jesper JENSEN; Thomas Ulrich CHRISTIANSEN
- Web page: https://patentgrep.com/patent/US20190379985A1

## CPC

- H04R 25/353: {Frequency, e.g. frequency shift or compression}
- H04R 25/505: {using digital signal processing}
- H04R 2225/43: Signal processing in hearing aids to enhance the speech intelligibility
- H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K)

## Abstract

A hearing device comprises a) an input unit for providing at least one electric input signal representing sound in a frequency sub-band representation, b) an SNR estimation unit for estimating a signal to noise ratio and/or a level estimation unit for estimating a level of said at least one electric input signal, and c) a configurable frequency transposition unit for transposing content of a source frequency sub-band FBS into a destination frequency sub-band FBD. The contents of the modified destination frequency sub-band is determined as a weighted combination of the contents of the source and destination frequency sub-bands according to the expression c1) PDmod=αPD+βPS or c2) MAGDmod=αMAGD+βMAGS, wherein PD and MAGD and PDmod and MAGDmod are the unmodified and modified power spectrum and magnitude, respectively, of the destination frequency sub-band, and PS and MAGS are the power spectrum and magnitude, respectively, of the source frequency sub-band, and the parameters α and β are destination and source band weight factors, respectively, that specify details of the frequency transposition operation. The weight factors α and β are determined in dependence of the estimate of signal to noise ratio and/or the estimate of level.

## Claims

### Claim 1

A hearing device adapted to be worn at or in an ear of a user, or adapted to be fully or partially implanted in the head of the user, the hearing device comprising
an input unit for providing at least one electric input signal representing sound in a frequency sub-band representation (k, m), where k and m are frequency and time indices, respectively,
an SNR estimation unit for estimating a signal to noise ratio and/or a level estimation unit for estimating a level of said at least one electric input signal, or a signal or signals derived therefrom, in said frequency sub-band representation,
and a configurable frequency transposition unit for transposing content of a source frequency sub-band FBs into a destination frequency sub-band FBD so that the contents of the resulting destination frequency sub-band is determined as a weighted combination of the contents of the source and destination frequency sub-bands according to the expression
PDmod=αPD+βPS
or
MAGDmod=αMAGD+βMAGS
wherein PD and MAGD are the unmodified power spectrum and magnitude, respectively, of the destination frequency sub-band before frequency transposition, PS and MAGS are the power spectrum and magnitude, respectively, of the source frequency sub-band, and PDmod and MAGDmod are the resulting power spectrum and magnitude, respectively, in the resulting destination sub-band after the frequency transposition, and the parameters a and are destination and source band weight factors, respectively, that specify details of the frequency transposition operation, and wherein
said configurable frequency transposition unit is configured to determine at least one of said weight factors α and β in dependence of said estimate of signal to noise ratio and/or said estimate of level of said at least one electric input signal, or a signal or signals derived therefrom.

### Claim 2 (depends on 1)

A hearing device according to claim 1 wherein at least one of said weight factors α and β is(are) determined in dependence of said estimate of signal to noise ratio and/or said estimate of level of said at least one electric input signal, or a signal or signals derived therefrom, in said destination and/or source frequency sub-bands.

### Claim 3 (depends on 1)

A hearing device according to claim 1 wherein at least one of said source and/or destination frequency sub-band(s) are/is determined in dependence of characteristics of said at least one electric input signal, or a signal or signals derived therefrom.

### Claim 4 (depends on 1)

A hearing device according to claim 1 wherein at least one of said source and/or destination frequency sub-band(s) is(are) pre-determined.

### Claim 5 (depends on 1)

A hearing device according to claim 1 configured to provide that said configurable frequency transposition unit is activated by an activation input in a specific mode of operation and/or when specific conditions are fulfilled.

### Claim 6 (depends on 5)

A hearing device according to claim 5 configured to provide that said specific condition comprises that the estimated signal to noise ratio (SNR) and/or the estimated level (LS) of the source band signal is relatively high AND that the estimated signal to noise ratio (SNR) and/or the estimated level (LD) of the destination band signal is relatively low.

### Claim 7 (depends on 5)

A hearing device according to claim 5 configured to provide that said specific condition is or comprises that a voice is estimated to be present in the source band signal.

### Claim 8 (depends on 1)

A hearing device according to claim 1 wherein said weight factors α and β are subject to a constraint.

### Claim 9 (depends on 1)

A hearing device according to claim 1 wherein said configurable frequency transposition unit is configured to determine said weight factors α and β under the constraint of a performance goal or a cost function.

### Claim 10 (depends on 9)

A hearing device according to claim 9 wherein said performance goal or cost function comprises one of a measure Î of a) listening effort b) sound quality, and c) speech intelligibility.

### Claim 11 (depends on 10)

A hearing device according to claim 10 wherein optimal weight factors α* and β* are determined from a database of known combinations of said weight factors (α, β), said power spectra (PD, PS) and/or magnitudes (MAGD, MAGS) of said destination and source frequency sub-bands, and corresponding values of the chosen measure Î.

### Claim 12 (depends on 11)

A hearing device according to claim 11 wherein said optimal weight factors α* and β* are determined from a database Dim comprising corresponding values of
PD,i, SNR(PD,i,x), PS,j, SNR(PS,j,x), i−1, . . . , NI, j=1, . . . , NJ, x−1, . . . , NX, where NI, and NJ are the number of different values of destination and source sub-band power spectra, respectively, and NX is the number of different values of SNR for each power spectrum value PD, PS;
α*i,j,xβ*i,j,x, i=1, . . . , NI, j−1, . . . , NJ, x=1, . . . , NX;
where said optimal weight factors are determined as the values α* and β* of said weight factors αi,j,x and βi,j,x corresponding to a value Î*(α*, β*, PD, SNR(PD), PS, SNR(PS)) of said chosen measure Î, e.g. speech intelligibility, that fulfills, e.g. maximizes, said performance goal, or, e.g. minimizes, said cost function.

### Claim 13 (depends on 1)

A hearing device according to claim 1 wherein said input unit comprises a beamformer filtering unit configured to spatially filter at least two input signals representing sound in the environment said user, and providing said at least one electric input signal as a beamformed signal.

### Claim 14 (depends on 1)

A hearing device according to claim 1 being constituted by or comprising a hearing aid, a headset, an earphone, an ear protection device or a combination thereof.

### Claim 15

A method of operating a hearing device, e.g. a hearing aid, adapted to be worn by a user at or in an ear of the user, or adapted to be fully or partially implanted in the head of the user, the method comprising
providing at least one electric input signal representing sound in a frequency sub-band representation (k, m), where k and m are frequency and time indices, respectively,
estimating a signal to noise ratio of said at least electric input signal, or a signal or signals derived therefrom, in said time frequency representation,
transposing content of a source frequency sub-band FBs into a destination frequency band FBD so that the contents of the destination frequency sub-band is determined as a weighted combination of the contents of the source and destination frequency sub-bands according to the expression
PDmod=αPD+βPS
or
MAGDmod=αMAGD+βMAGS
wherein PD and MAGD is the unmodified power spectrum and magnitude, respectively, of the destination frequency sub-band before frequency transposition, PS and MAGS is the power spectrum or magnitude, respectively, of the source frequency sub-band, and PDmod and MAGDmod is the resulting power spectrum or magnitude, respectively, in the resulting destination sub-band after the frequency transposition, and the parameters α and β are destination and source band weight factors, respectively, that specify details of the frequency transposition operation, and
determining at least one of said weight factors α and β in dependence of said estimate of signal to noise ratio and/or said estimate of level of said at least one electric input signal or a signal or signals derived therefrom.

### Claim 16 (depends on 15)

A method according to claim 15 comprising determining said weight factors α and β in dependence of said estimate of signal to noise ratio and/or said estimate of level of said at least one electric input signal or a signal or signals derived therefrom in said destination and/or source frequency sub-bands.

### Claim 17 (depends on 15)

A method according to claim 15 wherein said source frequency sub-band and said destination frequency sub-band are located on each side of a threshold frequency determined in advance of use of said hearing device with a view to a hearing profile of the user.

### Claim 18 (depends on 15)

A method according to claim 15 wherein said source frequency sub-band and/or said destination frequency sub-band is/are determined in advance of use of said hearing device with a view to a hearing profile of the user.

### Claim 19 (depends on 15)

A method according to claim 15 wherein said source frequency sub-band and/or said destination frequency sub-band is/are adaptively determined in dependence of a current electric input signal.

### Claim 20 (depends on 15)

A non-transitory computer readable storage medium storing a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method of claim 15.