# US 8,787,605 B2 · Frequency translation in hearing assistance devices using additive spectral synthesis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,787,605 B2 - Document ID: US8787605B2 - Status: Granted - Kind: B2 - Application number: 13/916,392 - Filed: 2013-06-12 - Published: 2013-12-19 - Granted: 2014-07-22 - Earliest claimed: 2012-06-15 - Assignees: Starkey Laboratories, Inc. - Applicants: Starkey Laboratories, Inc. - Inventors: Kelly Fitz - Web page: https://patentgrep.com/patent/US8787605B2 ## CPC - H04R 25/353: {Frequency, e.g. frequency shift or compression} - 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 Disclosed herein, among other things, is a system for frequency translation by high-frequency spectral envelope warping in hearing assistance devices. The present subject matter relates to improved speech intelligibility in a hearing assistance device using frequency translation by high-frequency spectral envelope warping. The system described herein implements an algorithm for performing frequency translation in an audio signal processing device for the purpose of improving perceived sound quality and speech intelligibility in an audio signal when presented using a system having reduced bandwidth relative to the original signal, or when presented to a hearing-impaired listener sensitive to only a reduced range of acoustic frequencies. ## Claims ### Claim 1 A method for processing an audio signal received by a hearing assistance device, the method comprising: filtering the audio signal to generate a high frequency filtered signal, the filtering performed at a splitting frequency; transposing at least a portion of an audio spectrum of the filtered signal to a lower frequency range by a transposition process to produce a transposed audio signal; and summing the transposed audio signal with the audio signal to generate an output signal, wherein the transposition process uses a prototype spectral peak modulated by a sinusoid having a time varying amplitude and frequency to control a center frequency and magnitude of a translated spectral feature. ### Claim 2 (depends on 1) The method of claim 1, wherein using the prototype spectral peak includes using a noise signal configured to be filtered to obtain a narrowband, low pass noise signal. ### Claim 3 (depends on 1) The method of claim 1, wherein using the prototype spectral peak includes using random samples generated at a decimated rate and up-sampled using interpolation or smoothing. ### Claim 4 (depends on 1) The method of claim 1, wherein using the prototype spectral peak includes using a single fixed-coefficient prototype low pass filter. ### Claim 5 (depends on 1) The method of claim 1, wherein modulating the prototype spectral peak includes using a look up table. ### Claim 6 (depends on 1) The method of claim 1, wherein the bandwidth and shape of the prototype spectral peak does not vary with the magnitude of the translated spectral feature. ### Claim 7 (depends on 1) The method of claim 1, wherein using the prototype spectral peak includes producing two or more peaks at different magnitudes without changing shape of either peak, to provide distinctive spectra for different translated sounds. ### Claim 8 (depends on 1) The method of claim 1, comprising using a weighted sum of narrowband spectra to compute a translated spectrum. ### Claim 9 (depends on 1) The method of claim 1, comprising multiplying by a sum of two or more sinusoids to render multiple translated peaks simultaneously. ### Claim 10 (depends on 1) The method of claim 1, comprising using a translated spectral envelope filter to increase low frequency energy suppressed by the splitting filter. ### Claim 11 (depends on 1) The method of claim 1, wherein the center frequency and magnitude of the translated spectral feature are configured to be updated for each block. ### Claim 12 (depends on 1) The method of claim 1, wherein the prototype spectral peak has a width of approximately 500 Hz, and is produced using a spectral envelope filter having a bandwidth of approximately 2 to 3 kHz. ### Claim 13 A system for processing an audio signal received by a hearing assistance device, the system comprising: a digital signal processor programmed to perform the steps of: filtering the audio signal to generate a high frequency filtered signal, the filtering performed at a splitting frequency; transposing at least a portion of an audio spectrum of the filtered signal to a lower frequency range by a transposition process to produce a transposed audio signal; and summing the transposed audio signal with the audio signal to generate an output signal, wherein the transposition process uses a prototype spectral peak modulated by a sinusoid having a time varying amplitude and frequency to control a center frequency and magnitude of a translated spectral feature. ### Claim 14 (depends on 13) The system of claim 13, wherein the hearing assistance device includes a hearing aid. ### Claim 15 (depends on 14) The system of claim 14, wherein the hearing aid includes an in-the-ear (ITE) hearing aid. ### Claim 16 (depends on 14) The system of claim 14, wherein the hearing aid includes a behind-the-ear (BTE) hearing aid. ### Claim 17 (depends on 14) The system of claim 14, wherein the hearing aid includes an in-the-canal (ITC) hearing aid. ### Claim 18 (depends on 14) The system of claim 14, wherein the hearing aid includes a receiver-in-canal (RIC) hearing aid. ### Claim 19 (depends on 14) The system of claim 14, wherein the hearing aid includes a completely-in-the-canal (CIC) hearing aid. ### Claim 20 (depends on 14) The system of claim 14, wherein the hearing aid includes a receiver-in-the-ear (RITE) hearing aid.