# US 11,443,725 B2 · Acoustic meta material passive spiral audio amplifier and a method to make the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,443,725 B2 - Document ID: US11443725B2 - Status: Granted - Kind: B2 - Application number: 17/164,914 - Filed: 2021-02-02 - Published: 2021-08-26 - Granted: 2022-09-13 - Earliest claimed: 2020-02-25 - Assignees: Acoustic Metamaterials LLC - Applicants: Acoustic Metamaterials LLC - Inventors: Gopal P. Mathur - Web page: https://patentgrep.com/patent/US11443725B2 ## CPC - G10K 11/08: Non-electric sound-amplifying devices, e.g. non-electric megaphones (amplifying by horns G10K11/02; amplifying by focusing G10K11/26) - G10K 11/22: for conducting sound through hollow pipes, e.g. speaking tubes - H04R 1/028: {associated with devices performing functions other than acoustics, e.g. electric candles} - H04R 1/2857: {for loudspeaker transducers} - H04R 1/345: {for loudspeakers} - H04R 2499/11: Transducers incorporated or for use in hand-held devices, e.g. mobile phones, PDA's, camera's - H04R 2499/15: Transducers incorporated in visual displaying devices, e.g. televisions, computer displays, laptops - G10K: SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR - 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 acoustic meta material (AMM) spiral device for passive amplification of sound is described. The AMM amplifier device employs at least one deep sub-wavelength spiral design with high refraction index, based on an exponential spiral shape. The AMM spiral amplifier is used to focus on low frequency sound amplification and to cover broadband frequency range. Sound emanating from a speaker travels into a spiral channel until reaching the apex of the spiral. When twin spirals are used, the sound then enters a second spiral for radiating into open air. ## Claims ### Claim 1 A method of passively amplifying acoustic output of a speaker over a broad frequency range, comprising: aligning an opening into a first spiral channel towards a front side of a speaker; and amplifying sound emanating from said speaker, by guiding said sound into said channel via the opening, wherein said sound output from said speaker travels along said first spiral channel from a wide end to an apex thereof, and is output to a surrounding environment from an opening at said apex of said first spiral channel, wherein the speaker is mounted directly to said opening. ### Claim 2 (depends on 1) The method of claim 1, further comprising, prior to said aligning, configuring at least one of a frequency range and an amplification pattern of said first spiral channel. ### Claim 3 (depends on 1) The method of claim 1, wherein said speaker is an internal speaker of an electronic computing device. ### Claim 4 (depends on 3) The method of claim 3, wherein said first spiral channel is fixedly attached to a unitary housing, and said unitary housing covers substantially a side of said electronic computing device. ### Claim 5 (depends on 3) The method of claim 3, wherein said electronic computing device comprises a cellular phone network transceiver, a display, said speaker, and a microphone. ### Claim 6 A passive frequency amplifier comprising a first spiral channel extending from a first sound intake opening at a wide end of said first spiral channel to a first sound exit at an apex of said first spiral channel, wherein said first spiral channel is adapted to receive sound output from a front side of a speaker and to amplify said sound by said sound travelling from said first sound intake opening to said first sound exit and being output to a surrounding environment from said first sound exit at said apex of said first spiral channel, wherein said front side of said speaker is mounted directly to said opening and coupled to said first spiral channel. ### Claim 7 (depends on 6) An amplification system, comprising: a passive frequency amplifier according to claim 6; and said speaker outputting sound substantially toward said first sound intake opening at said wide end of said first spiral channel, wherein said sound output from said speaker travels along said first spiral channel from said first sound intake opening at said wide end to said apex of said first spiral channel, and is output to a surrounding environment from said first sound exit at said apex of said first spiral channel. ### Claim 8 (depends on 7) The amplification system of claim 7, wherein said speaker is an internal speaker of an electronic computing device. ### Claim 9 (depends on 8) The amplification system of claim 8, wherein said first spiral channel is fixedly attached to a unitary housing, and said unitary housing covers substantially a side of said electronic computing device. ### Claim 10 (depends on 8) The amplification system of claim 8, wherein said electronic computing device comprises a cellular phone network transceiver, a display, said speaker, and a microphone. ### Claim 11 (depends on 1) The method of claim 1, wherein said guiding comprises guiding said sound along said first spiral channel, said first spiral channel being devoid of closed loops. ### Claim 12 (depends on 6) The passive frequency amplifier of claim 6, wherein said first spiral channel is devoid of closed loops. ### Claim 13 A passive frequency amplifier comprising a first spiral channel extending from a first sound intake opening at a wide end of said first spiral channel to a first sound exit at an apex of said first spiral channel, said first spiral channel being devoid of closed loops, wherein said first spiral channel is adapted to receive sound output from a speaker and to amplify said sound by said sound travelling from said first sound intake opening to said first sound exit, wherein said speaker is mounted directly at an opening into said first spiral channel.