Overview

FILLTUNE Inc. (established April 2021, Minato Ward, Tokyo) develops hearing support devices based on the proprietary FILLTUNE® Engine — a giant magnetostrictive (GMT) bone conduction transducer — targeting users with sensorineural hearing loss for whom conventional hearing aids have proven ineffective [1]. The current lineup comprises the FILLTUNE CLEAR (1,407 USD equivalent, consumer channel [3][6]) and FILLTUNE WeCLEAR (2,814 USD equivalent, medical/institutional channel [4][6]), alongside the FILLTUNE a-tell ATL-25, a bidirectional bone conduction communication device for care settings. GMT technology uses specialized alloy magnetostrictive elements claimed to transmit the full audible spectrum to the cochlea, differentiating it from the piezoelectric transducers used by mainstream bone conduction manufacturers [2]. The technology has roots in a 2013 Japan Ministry of Health, Labour and Welfare disability support device development program. Because these products are presented for hearing support and medical/institutional use, this review does not evaluate medical efficacy, safety, indications, fitting, or clinical suitability; the scoring below evaluates only sound quality as audio equipment, user-facing audio functions, and published audio measurements [2][4].

Scientific Validity

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No independent third-party measurements exist for FILLTUNE products, and the only manufacturer-stated audio specification is a frequency response range of 20Hz–20kHz with no deviation values or test conditions [2][3]. Scientific Validity cannot be meaningfully evaluated; score set to 0.5.

Technology Level

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FILLTUNE’s core technology — the Giant Magnetostrictive Transducer (FILLTUNE® Engine / PRESTIN® Engine) — is genuinely proprietary with confirmed patent filings for the GMT transducer technology [1][2]. FILLTUNE is, as of the review date, the only commercial entity to have successfully brought supermagnetostrictive bone conduction to market in hearing support devices, representing more than 13 years of accumulated engineering know-how spanning the FY2013 government disability support program through to the 2024 second-generation product line and the 2025 a-tell ATL-25. The specialized alloy element manufacturing process and patent estate create a genuine competitive barrier that new entrants would require more than three years to replicate — underscored by the commercial discontinuation of the earlier TEAC-distributed predecessor, which demonstrates the difficulty of this technology even for established audio manufacturers.

Two factors temper the score. First, the GMT technology’s roots in 2007–2013 mean it is 13–19 years old as of 2026 and cannot be characterized as recently developed. Second, the mainstream bone conduction market has continued using piezoelectric transducers without adopting GMT across the same 13+ year period, providing strong market evidence that the technology is not currently considered desirable by industry peers. The Bluetooth 5.0 / SBC integration and three-microphone array represent standard contemporary implementation, not advanced AI or cloud-based integration.

Cost-Performance

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Within that audio-only scope, this site evaluates based solely on functionality and measured performance values, without considering driver types or configurations.

CP evaluation covers two representative products. FILLTUNE CLEAR (1,407 USD equivalent [3][6]) is weighted at 0.6 as the primary consumer-channel product; FILLTUNE WeCLEAR (2,814 USD equivalent [4][6]) is weighted at 0.4 as the institutional-channel variant.

Core user-facing functions (both products): ambient sound collection/amplification mode via integrated microphone array, Bluetooth 5.0 streaming (A2DP, SBC), multi-point connection to 2 devices simultaneously, USB-C charging, and bone conduction hearing support delivery.

FILLTUNE CLEAR — 1,407 USD equivalent [3][6]

The cheapest confirmed equivalent-or-better product is the OHM Electric AudioComm HP-BC500N, available from 62 USD equivalent [5][6]. The HP-BC500N provides equivalent-or-better user-facing functions within this audio-only scope: ambient sound collection/amplification mode via a dedicated sound collector transmitter, Bluetooth 5.0 streaming with SBC and AAC codecs (equal-or-better codec support), multi-point connection, IPX6 waterproofing (FILLTUNE CLEAR unspecified), and superior battery life (6h music / 20h sound collection vs. 5h / 8h).

Performance comparison (all values manufacturer-stated; no independent measurements exist for any product in this category):

• Frequency Response: FILLTUNE CLEAR “20Hz–20kHz” (manufacturer claim, no ±dB or test conditions [2]) vs. HP-BC500N “20Hz–20kHz” (A2DP codec bandwidth; bone conduction transducer FR not independently documented [5]) — provisional equivalent
• THD: Not documented for either product
• S/N Ratio: Not documented for either product

All audio performance comparisons are provisional. Results should be revised when independent measurements become available.

CP = 62 USD ÷ 1,407 USD = 0.044 -> 0.0

FILLTUNE WeCLEAR — 2,814 USD equivalent [4][6]

The same OHM Electric AudioComm HP-BC500N (62 USD equivalent [5][6]) provides equivalent-or-better user-facing audio functions in the hearing support domain — sound collection/amplification, Bluetooth streaming, multi-point connection, and IPX6 waterproofing. Audio performance metrics are equally undocumented for both products; the comparison remains provisional and does not address medical efficacy or clinical suitability.

CP = 62 USD ÷ 2,814 USD = 0.022 -> 0.0

Weighted Average:

Weighted CP = (0.0 x 0.6) + (0.0 x 0.4) = 0.0 -> 0.0

The CLEAR and WeCLEAR prices are approximately 23× and 45× the price of the cheapest confirmed equivalent alternative, respectively.

Reliability & Support

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Warranty duration is not publicly stated on any official FILLTUNE channel [1][3]; a warranty certificate is included with the product but the coverage period is undisclosed. Support is provided primarily through medical equipment distributors (WiSM/Mutoh Medical) with a manufacturer inquiry form as a supplementary direct channel — qualifying as dealer-based support without a confirmed global service infrastructure. Distribution is Japan-only with no confirmed international repair or replacement programs. No statistical failure rate data (RMA rate, MTBF) has been published, and no product recalls or documented defect reports were identified as of the review date. FILLTUNE was established in April 2021, so a long-term reliability track record cannot yet be established. Firmware update availability for the Bluetooth-enabled devices is undocumented. No special support services such as on-site repair or same-day replacement are confirmed.

Rationality of Design Philosophy

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FILLTUNE pursues a genuine and focused engineering goal — using GMT bone conduction to bypass damaged outer hair cells and deliver auditory stimulation to the cochlea for users with sensorineural hearing loss — and earns credit for its genuinely innovative approach. The technology is backed by confirmed patents and manufacturer/distributor-cited clinical testing in a government-recognized program, where about 60% of subjects with severe hearing loss were reported to receive recognizable hearing under Japanese 100-word speech recognition listening/writing testing [2]. This review does not treat that clinical claim as evidence of audio fidelity, but the company’s dedicated focus on a specific unmet medical need across multiple product generations represents a coherent development philosophy.

Two factors reduce the score below baseline. First, the price premium of 1,407-2,814 USD equivalent against 62 USD equivalent for the cheapest confirmed equivalent alternative is not transparently justified by published audio performance data, indicating a substantial proportion of costs that cannot be attributed to verifiable audio-function improvements [3][4][5][6]. Second, FILLTUNE’s marketing material presents transducer mechanical specifications — element response speed measured in microseconds to nanoseconds, audio reproduction rates of 1 million to 100 million cycles per second, and claims of 1,000–100,000 times greater audio reproduction than conventional speakers [2] — as implying audible superiority. These are properties of the magnetostrictive element’s mechanical response rate, not audio performance metrics; element cycle rates in the MHz range do not produce audible benefits beyond the 20 kHz ceiling of human hearing, making these assertions of audible effects for parameters that produce no audible differences.

Advice

FILLTUNE’s products are designed for a highly specific use case: bone conduction hearing support for individuals with sensorineural hearing loss who have not benefited from conventional hearing aids. If this describes your clinical situation, FILLTUNE’s GMT technology represents the most developed commercial implementation of supermagnetostrictive bone conduction identified in this review, with manufacturer/distributor-cited clinical testing in a government-recognized program [2]. Medical suitability should be judged by an audiologist or other qualified clinician, not by this audio-quality review.

For users seeking bone conduction audio for general listening, exercise, or everyday ambient hearing augmentation without a specific clinical need for FILLTUNE’s technology, functionally equivalent hearing support alternatives are available at substantially lower cost. The OHM Electric AudioComm HP-BC500N [5] provides bone conduction hearing support with ambient sound collection, Bluetooth streaming, IPX6 waterproofing, and superior battery life at 62 USD equivalent — approximately 4% of FILLTUNE CLEAR’s price — with no published evidence that FILLTUNE’s bone conduction audio performance, if superior, justifies the remaining premium [6]. No independent audio performance measurements exist for FILLTUNE products as of the review date, and prospective buyers should note that FILLTUNE’s audio quality claims have not been verified by any independent measurement source.

References

[1] FILLTUNE Inc. — Official Website — https://filltune.com/ — accessed 2026-05-08

[2] FILLTUNE WeCLEAR — Technology Page — https://filltune-weclear.com/technology.html — accessed 2026-05-08

[3] FILLTUNE CLEAR (CLR-25) — Official EC Store — https://filltune.official.ec/items/127890559 — accessed 2026-05-08; price: 1,407 USD equivalent, tax-inclusive

[4] Nichii Medical Web Catalog — FILLTUNE WeCLEAR — https://sfwebcatalog.nichii.net/detail/gg/2938/ — accessed 2026-05-08; price: 2,814 USD equivalent, tax-inclusive

[5] OHM Electric — AudioComm HP-BC500N (03-1700) — https://www.ohm-electric.co.jp/product/c10/c1015/874210/ / Price comparison via kakaku.com: https://kakaku.com/item/K0001505268/ — accessed 2026-05-08; minimum market price 62 USD equivalent

[6] European Central Bank — Euro foreign exchange reference rates API — https://data-api.ecb.europa.eu/service/data/EXR/D.USD+JPY.EUR.SP00.A?startPeriod=2026-05-07&endPeriod=2026-05-07 — accessed 2026-05-08; 2026-05-07 published rates imply a conversion factor of 156.39 local currency units per USD

(2026.5.9)