# US 2013/0156227 A1 · Sound output device and method of adjusting sound volume > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0156227 A1 - Document ID: US20130156227A1 - Status: Published application - Kind: A1 - Application number: 13/680,475 - Filed: 2012-11-19 - Published: 2013-06-20 - Earliest claimed: 2011-12-15 - Assignees: Funai Electric Co., Ltd. - Inventors: Akifumi MATSUMURA - Web page: https://patentgrep.com/patent/US20130156227A1 ## CPC - H03G 3/20: Automatic control ({H03G3/005 takes precedence;} combined with volume compression or expansion H03G7/00) - H03G 7/007: {of digital or coded signals} - H03G: CONTROL OF AMPLIFICATION ## Abstract A sound output device of the present invention is one that receives a digital audio signal including a plurality of channels and performs digital signal processing on the received digital audio signal, and includes a detecting portion which detects peak values or effective values of the plurality of channels included in the digital audio signal. The sound output device also includes an electric power calculating portion which calculates necessary electric power to output sound of each of the channels according to the peak values or the effective values. The sound output device also includes a sound volume adjusting portion which adjusts sound volume of the digital audio signal according to a total of the necessary electric power calculated by the electric power calculating portion for each of the channels. ## Claims ### Claim 1 A sound output device which receives a digital audio signal including a plurality of channels and performs digital signal processing on the received digital audio signal, the sound output device comprising: a detecting portion which detects peak values or effective values of the plurality of channels included in the digital audio signal; an electric power calculating portion which calculates necessary electric power to output sound of each of the channels according to the peak values or the effective values; and a sound volume adjusting portion which adjusts sound volume of the digital audio signal according to a total of the necessary electric power calculated by the electric power calculating portion for each of the channels. ### Claim 2 (depends on 1) The sound output device according to claim 1, further comprising: a compressing portion which performs compression of a dynamic range of a digital audio signal; and a discriminating portion which discriminates a largest peak value or a largest effective value of the peak values or the effective values of the plurality of channels, wherein the sound volume adjusting portion compares the peak value or the effective value discriminated by the discriminating portion with a predetermined threshold, and if the peak value or the effective value exceeds the threshold, the sound volume adjusting portion instructs the compressing portion to perform the compression. ### Claim 3 (depends on 2) The sound output device according to claim 2, further comprising a threshold recording portion having recorded therein; a first threshold indicating an allowable output electric power of a power supply incorporated in the sound output device; and a second threshold indicating a limit of a range of power under which the power supply is protected in a case of a complete short circuit of the power supply, wherein the sound volume adjusting portion instructs the compressing portion to perform the compression if the total exceeds the first threshold but does not exceed the second threshold. ### Claim 4 (depends on 3) The sound output device according to claim 3, further comprising a mute portion which performs muting of a digital audio signal, wherein, if the total exceeds the second threshold, the sound volume adjusting portion instructs the mute portion to perform muting of a digital signal and instructs the compressing portion to perform the compression, and after the compression is completed, the sound volume adjusting portion instructs the mute portion to cancel the muting. ### Claim 5 (depends on 4) The sound output device according to claim 4, wherein, in instructing the compressing portion to perform the compression, the sound volume adjusting portion instructs the compressing portion: to find a maximum value of the peak or effective values of the plurality of channels detected by the detecting portion; to calculate a degree of attenuation between the maximum value and a maximum value previously set according to a standard of the digital audio signal; and to perform the compression based on a value obtained by attenuating the degree of attenuation by a predetermined degree. ### Claim 6 (depends on 5) The sound output device according to claim 5, wherein, if the total still exceeds the first threshold after the sound volume adjusting portion instructs the compressing portion to perform the compression, the sound volume adjusting portion instructs the compressing portion to perform the compression with a further increased degree of attenuation, and the sound volume adjusting portion instructs the compressing portion to stop the compression at an instant when a time period during which the total is larger than the first threshold exceeds a predetermined time length. ### Claim 7 (depends on 6) The sound output device according to claim 6, further comprising: an audio decoder which decodes encoded audio data to generate a digital audio signal; and an amplifier which amplifies sound. ### Claim 8 A sound volume adjusting method for adjusting volume of sound output from a sound output device, comprising the steps of: performing compression of a dynamic range of a digital audio signal; finding a maximum value of peak values or effective values of a plurality of channels included in the digital audio signal; comparing the maximum value of the peak values or the effective values with a predetermined threshold; and performing the compression if the maximum value of the peak values or the effective values exceeds the threshold.