# US 10,313,790 B1 · Polymorphic playback system with switching oscillation prevention > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,313,790 B1 - Document ID: US10313790B1 - Status: Granted - Kind: B1 - Application number: 16/103,339 - Filed: 2018-08-14 - Granted: 2019-06-04 - Earliest claimed: 2018-08-14 - Assignees: Cirrus Logic, Inc. - Applicants: Cirrus Logic International Semiconductor Ltd. - Inventors: Ku He; Tejasvi Das; John L. Melanson - Web page: https://patentgrep.com/patent/US10313790B1 ## CPC - H04R 3/02: for preventing acoustic reaction {, i.e. acoustic oscillatory feedback (specially adapted for hearing aids H04R25/453)} - G11B 20/24: for reducing noise {(control of amplification in general, e.g. dependent upon noise level H03G)} - G11B 27/022: Electronic editing of analogue information signals, e.g. audio or video signals - H04R 3/00: Circuits for transducers (arrangements for producing a reverberation or echo sound G10K15/08; amplifiers H03F) - G10L 21/0208: Noise filtering - G10L 25/51: for comparison or discrimination - H03G 3/3005: {in amplifiers suitable for low-frequencies, e.g. audio amplifiers (H03G3/32, H03G3/34 take precedence)} - H03G 5/00: Tone control or bandwidth control in amplifiers - 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) - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - G10L: SPEECH ANALYSIS TECHNIQUES OR SPEECH SYNTHESIS; SPEECH RECOGNITION; SPEECH OR VOICE PROCESSING TECHNIQUES; SPEECH OR AUDIO CODING OR DECODING - H03G: CONTROL OF AMPLIFICATION ## Abstract A polymorphic playback system in which one or more parameters of a signal path of the polymorphic playback system are varied based on one or more characteristics of a playback signal processed by the signal path may include a control subsystem configured to detect an out-of-band noise profile of the playback signal and set one or more playback signal magnitude thresholds for switching between polymorphic modes of the polymorphic playback system based on the out-of-band noise profile, wherein the polymorphic modes comprise at least a first polymorphic mode in which one or more first parameters are applied to the signal path and a second polymorphic mode in which one or more second parameters are applied to the signal path. ## Claims ### Claim 1 A polymorphic playback system wherein one or more parameters of a signal path of the polymorphic playback system are varied based on one or more characteristics of a playback signal processed by the signal path, comprising a control subsystem configured to: detect an out-of-band noise profile of the playback signal; and set one or more playback signal magnitude thresholds for switching between polymorphic modes of the polymorphic playback system based on the out-of-band noise profile, wherein the polymorphic modes comprise at least a first polymorphic mode in which one or more first parameters are applied to the signal path and a second polymorphic mode in which one or more second parameters are applied to the signal path. ### Claim 2 (depends on 1) The system of claim 1, wherein the control subsystem is configured to detect the out-of-band noise profile by filtering to extract an out-of-band noise characterization from the playback signal. ### Claim 3 (depends on 1) The system of claim 1, wherein the control subsystem is configured to detect the out-of-band noise profile by analyzing statistics associated with the playback signal. ### Claim 4 (depends on 3) The system of claim 3, wherein the statistics are indicative of a frequency of occurrence of the playback signal crossing the one or more playback signal magnitude thresholds. ### Claim 5 (depends on 1) The system of claim 1, wherein the setting of the one or more playback signal magnitude thresholds minimizes switching between the polymorphic modes due to out-of-band noise. ### Claim 6 (depends on 1) The system of claim 1, wherein the setting of the one or more playback signal magnitude thresholds comprises setting a range of hysteresis between a first threshold for switching from a first polymorphic mode to a second polymorphic mode, and a second threshold for switching from the second polymorphic mode to the first polymorphic mode such that the range of hysteresis increases for higher levels of out-of-band noise and decreases for lower levels of out-of-band noise. ### Claim 7 A method for use in a polymorphic playback system wherein one or more parameters of a signal path of the polymorphic playback system are varied based on one or more characteristics of a playback signal processed by the signal path, comprising: detecting an out-of-band noise profile of the playback signal; and setting one or more playback signal magnitude thresholds for switching between polymorphic modes of the polymorphic playback system based on the out-of-band noise profile, wherein the polymorphic modes comprise at least a first polymorphic mode in which one or more first parameters are applied to the signal path and a second polymorphic mode in which one or more second parameters are applied to the signal path. ### Claim 8 (depends on 7) The method of claim 7, wherein a control subsystem is configured to detect the out-of-band noise profile by filtering to extract an out-of-band noise characterization from the playback signal. ### Claim 9 (depends on 7) The method of claim 7, wherein a control subsystem is configured to detect the out-of-band noise profile by analyzing statistics associated with the playback signal. ### Claim 10 (depends on 9) The method of claim 9, wherein the statistics are indicative of a frequency of occurrence of the playback signal crossing the one or more playback signal magnitude thresholds. ### Claim 11 (depends on 7) The method of claim 7, wherein the setting of the one or more playback signal magnitude thresholds minimizes switching between the polymorphic modes due to out-of-band noise. ### Claim 12 (depends on 7) The method of claim 7, wherein the setting of the one or more playback signal magnitude thresholds comprises setting a range of hysteresis between a first threshold for switching from a first polymorphic mode to a second polymorphic mode, and a second threshold for switching from the second polymorphic mode to the first polymorphic mode such that the range of hysteresis increases for higher levels of out-of-band noise and decreases for lower levels of out-of-band noise.