# US 10,483,931 B2 · Audio device, speaker device, and audio signal processing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,483,931 B2 - Document ID: US10483931B2 - Status: Granted - Kind: B2 - Application number: 15/919,737 - Filed: 2018-03-13 - Published: 2018-09-27 - Granted: 2019-11-19 - Earliest claimed: 2017-03-23 - Assignees: Yamaha Corporation - Applicants: Yamaha Corporation - Inventors: Katsumasa Kosuge; Tomoko Ninomiya - Web page: https://patentgrep.com/patent/US10483931B2 ## CPC - H03G 3/32: the control being dependent upon ambient noise level or sound level - H03G 5/165: {Equalizers; Volume or gain control in limited frequency bands} - H03G 7/002: {in untuned or low-frequency amplifiers, e.g. audio amplifiers (H03G7/007, H03G7/001, H03G7/008, H03G7/02, H03G7/06 take precedence)} - H03G 9/025: {frequency-dependent volume compression or expansion, e.g. multiple-band systems (H03G9/10, H03G9/18 take precedence)} - H04R 3/04: for correcting frequency response - H04R 29/001: {for loudspeakers (H04R29/007 takes precedence)} - H04R 2430/01: Aspects of volume control, not necessarily automatic, in sound systems - H04R 2430/03: Synergistic effects of band splitting and sub-band processing - H03G: CONTROL OF AMPLIFICATION - 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 An audio device includes: a first detector configured to detect a volume of a first audio signal; and a low-frequency component adjuster configured to generate a second audio signal in which a level of a low-frequency component of the first audio signal is adjusted based on the volume detected by the first detector. ## Claims ### Claim 1 An audio device comprising: a user interface that receives a user instruction to set a volume of an input signal; a volume control circuit that generates a first audio signal obtained by adjusting the volume of the input signal in accordance with the user instruction; filters that change frequency characteristics of the first audio signal; a first detecting circuit that detects a volume of the first audio signal where the frequency characteristics thereof have been changed by the filters; and a low-frequency component adjusting circuit that generates a second audio signal by: lowering a level of a low-frequency component of the first audio signal in a case where the volume detected by the first detecting circuit exceeds a first predetermined threshold; and without lowering the level of the low-frequency component of the first audio signal in a case where the volume detected by the first detecting circuit does not exceed the first predetermined threshold. ### Claim 2 (depends on 1) The audio device according to claim 1, wherein the low-frequency component adjusting circuit includes a high-pass filter that lowers the level of the low-frequency component of the first audio signal. ### Claim 3 (depends on 1) The audio device according to claim 1, wherein the low-frequency component adjusting circuit includes a band-elimination filter that lowers the level of the low-frequency component of the first audio signal. ### Claim 4 (depends on 1) The audio device according to claim 1, wherein: the low-frequency component adjusting circuit includes a first filter and a second filter that have different frequency responses, in a case where the volume detected by the first detecting circuit exceeds the first predetermined threshold but does not exceed a second predetermined threshold that is higher than the first predetermined threshold, the first filter processes the first audio signal to generate the second audio signal, and in a case where the volume detected by the first detecting circuit exceeds the second predetermined threshold, the second filter processes the first audio signal to generate the second audio signal. ### Claim 5 (depends on 1) The audio device according to claim 1, wherein the first detecting circuit detects, as the volume, a maximum value of an amplitude of the first audio signal over a unit period. ### Claim 6 (depends on 1) The audio device according to claim 1, wherein the low-frequency component adjusting circuit generates the second audio signal by cross fading the audio signal with the first audio signal with the level of the low-frequency component thereof having been lowered. ### Claim 7 (depends on 1) The audio device according to claim 1, further comprising a compressing circuit that compresses a dynamic range of the second audio signal in accordance with a level of the second audio signal. ### Claim 8 (depends on 7) The audio device according to claim 7, further comprising: a second detecting circuit that detects a volume of the second audio signal, wherein the compressing circuit compresses the dynamic range in accordance with the volume detected by the second detecting circuit. ### Claim 9 A speaker device comprising: an audio device comprising; a user interface that receives a user instruction to set a volume of an input signal; a volume control circuit that generates a first audio signal obtained by adjusting the volume of the input signal in accordance with the user instruction; filters that change frequency characteristics of the first audio signal; a first detecting circuit that detects a volume of the first audio signal where the frequency characteristics thereof have been changed by the filters; and a low-frequency component adjusting circuit that generates a second audio signal by: lowering a level of a low-frequency component of the first audio signal in a case where the volume detected by the first detecting circuit exceeds a predetermined threshold; and without lowering the level of the low-frequency component of the first audio signal in a case where the volume detected by the first detecting circuit does not exceed the first predetermined threshold; and at least one speaker that emits sound based on the second audio signal. ### Claim 10 An audio signal processing method comprising: receiving an instruction to set a volume of an input signal; generating a first audio signal obtained by adjusting the volume of the input signal in accordance with a user instruction; changing frequency characteristics of the first audio signal; detecting a volume of the first audio signal where the frequency characteristics thereof have been changed; and generating a second audio signal by: lowering a level of a low-frequency component of the first audio signal in a case where the detected volume of the first audio signal exceeds a first predetermined threshold; and without lowering the level of the low-frequency component of the first audio signal in a case where the detected volume of the first audio signal does not exceed the first predetermined threshold. ### Claim 11 (depends on 1) The audio device according to claim 1, wherein the low-frequency component adjusting circuit includes at least one filter and a comparator. ### Claim 12 (depends on 10) The audio signal processing method according to claim 10, wherein the generating of the second audio signal uses a low-frequency component adjusting circuit that includes a high-pass filter that lowers the level of the low-frequency component of the first audio signal. ### Claim 13 (depends on 10) The audio signal processing method according to claim 10, wherein the generating of the second audio signal uses a low-frequency component adjusting circuit that includes a band-elimination filter that lowers the level of the low-frequency component of the first audio signal. ### Claim 14 (depends on 10) The audio signal processing method according to claim 10, wherein: the generating of the second audio signal uses a low-frequency component adjusting circuit that includes a first filter and a second filter that have different frequency responses, the detecting of the volume of the first audio signal uses a detecting circuit, in a case where the detected volume exceeds the first predetermined threshold but does not exceed a second predetermined threshold that is higher than the first predetermined threshold, the generating of the second audio signal filters the first audio signal using the first filter to generate the second audio signal, and in a case where the detected volume exceeds the second predetermined threshold, the generating of the second audio signal filters the first audio signal using the second filter to generate the second audio signal. ### Claim 15 (depends on 10) The audio signal processing method according to claim 10, wherein: the detecting of the volume of the first audio signal uses a detecting circuit, and the detecting circuit detects, as the volume, a maximum value of an amplitude of the first audio signal over a unit period. ### Claim 16 (depends on 10) The audio signal processing method according to claim 10, wherein: the generating of the second audio signal uses a low-frequency component adjusting circuit, and the low-frequency component adjusting circuit generates the second audio signal by cross fading the audio signal with the first audio signal with the level of the low-frequency component thereof having been lowered. ### Claim 17 (depends on 10) The audio signal processing method according to claim 10, further comprising compressing, using a compressing circuit, a dynamic range of the second audio signal in accordance with a level of the second audio signal. ### Claim 18 (depends on 17) The audio signal processing method according to claim 17, further comprising: detecting a volume of the second audio signal using a detecting circuit, wherein the compressing circuit compresses the dynamic range in accordance with the volume detected by the second detecting circuit. ### Claim 19 (depends on 10) The audio signal processing method according to claim 10, wherein the generating of the second audio signal uses a low-frequency component adjusting circuit that includes at least one filter and a comparator.