Overview

FILLTUNE CLEAR (CLR-25) is a bilateral wireless bone conduction hearing support device by FILLTUNE Inc. (Tokyo, est. April 2021), designed for individuals with sensorineural hearing loss who are dissatisfied with conventional hearing aids. It delivers audio via a proprietary giant magnetostrictive (GMT) transducer — the “FILLTUNE Engine” — which transmits vibrations through the temporal bone to the cochlea, bypassing damaged outer hair cells. The device is not classified as a medically certified hearing aid under Japanese regulation. This review evaluates FILLTUNE CLEAR only as an audio device and hearing-support device, and does not assess medical efficacy, diagnosis, treatment, or suitability for any individual hearing condition. It connects via Bluetooth 5.0 (SBC) and features an ambient sound amplification mode, independent left/right volume control, stereo microphones, and wired input via a USB-C to 3.5mm adapter. Current retail price is 1,406.65 USD (220,000円) [1]. The underlying GMT transducer technology was first commercialized circa 2007 and relaunched in wireless form by FILLTUNE Inc. in 2022.

Scientific Validity

\[\Large \text{0.5}\]

No manufacturer audio performance specifications (frequency response deviation, THD, S/N ratio) and no independent third-party measurements are available for this product. Scientific validity cannot be evaluated due to insufficient data.

Technology Level

\[\Large \text{0.5}\]

The FILLTUNE Engine is a fully in-house developed giant magnetostrictive bone conduction transducer, with development history traceable to CTO Tetsuji Kunishi’s PRESTIN® prototype (c. 2012) and earlier commercial implementations. In-house design ownership and over a decade of accumulated manufacturing and clinical know-how yield positive marks [2]. A Japan Ministry of Health, Labour and Welfare FY2013 Assistive Device Development project adoption, with approximately 60% of severe sensorineural hearing loss subjects showing phoneme recognition improvement in clinical testing, provides partial scientific validation [2][3].

However, the core transducer technology has not advanced fundamentally at the commercial product level. No confirmed patents have been identified in public searches. The Bluetooth implementation (5.0, SBC-only) lags current competing bilateral bone conduction devices shipping with BT 5.3 and broader codec support. No DSP-based equalization, app control, or AI/cloud integration is offered. The GMT hearing assistance application remains uncontested by competitors, but this reflects a small target market rather than an actively defended technology position.

Cost-Performance

\[\Large \text{0.2}\]

This evaluation is based solely on functionality and measured performance values, without considering driver types or configurations.

The FILLTUNE CLEAR is priced at 1,406.65 USD (220,000円) [1]. The cheapest identified equivalent-or-better product is the eEAR-BC-HPH-Pro (XBD-Global) at 279.98 USD [4], normalized to 304.98 USD to account for a minor wired analog input gap (FILLTUNE CLEAR includes a USB-C to 3.5mm adapter; the eEAR-BC-HPH-Pro does not, gap normalized via a ~25 USD Bluetooth audio transmitter).

The eEAR-BC-HPH-Pro provides bilateral bone conduction delivery to both ears, independent left/right volume control via dedicated per-side buttons, stereo dual-microphone ambient sound amplification with Voice/Indoor/Outdoor processing modes, Bluetooth 5.3 (superior to BT 5.0), and 7.5–8 hours battery life (exceeding the FILLTUNE CLEAR’s 5 hours). All core hearing support functions are equivalent-or-better.

Regarding measured performance: neither the FILLTUNE CLEAR nor the eEAR-BC-HPH-Pro publish acoustic frequency response deviation (±dB), THD, or S/N ratio data. No independent third-party measurements exist for either product. The equivalence determination is PROVISIONAL, based on manufacturer functional specifications only.

CP = 304.98 USD / 1,406.65 USD = 0.217

Reliability & Support

\[\Large \text{0.4}\]

The FILLTUNE CLEAR carries a 1-year warranty covering defects during normal use, valid for Japan domestic purchases only [1]. The 1-year period is below the 2-year industry average. Paid manufacturer-direct repair is available post-warranty where technically feasible, but no third-party service network exists. FILLTUNE Inc. was established in April 2021; no extended reliability track record is available. No product recalls, systematic defects, or documented higher-than-average failure rates have been identified. No firmware update history is publicly documented. The device uses a rechargeable lithium-ion battery subject to standard capacity degradation over time.

Rationality of Design Philosophy

\[\Large \text{0.4}\]

The FILLTUNE CLEAR addresses a legitimate functional need: GMT bone conduction for sensorineural hearing support cannot be replicated by general-purpose smartphone-plus-DAC combinations, providing clear justification for dedicated-equipment status. Partial clinical validation from a Japan Ministry of Health, Labour and Welfare FY2013 project provides some scientific grounding for the transducer approach [2][3].

Two factors reduce the score significantly. First, a substantial portion of the 220,000円 retail price is not attributable to functional or measurement performance improvement — the same core technology was offered in 2024 crowdfunding variants at 79,000–109,000円 [3], and the original predecessors sold at approximately 30,000–40,000円. This represents a meaningfully non-functional cost allocation. Second, the manufacturer has made claims exceeding what the available evidence supports: “reproducing sound 1,000 to 100,000 times more effectively than speakers” has no acoustic measurement basis; “100× more audio information than conventional electromagnetic bone conduction” is an unverified claim; and an early “world-first high-degree hearing loss support” claim was subsequently retracted [3]. No DSP equalization, app-based programmable fitting, or AI integration is offered.

Advice

The FILLTUNE CLEAR occupies a narrow niche: bilateral GMT bone conduction hearing support for users with sensorineural hearing loss who have not benefited from conventional hearing aids. The partial clinical validation from a Ministry of Health project is a meaningful differentiator. However, no independent acoustic measurements have been published for this product, making it impossible to objectively verify claimed performance. The 1,406.65 USD retail price is substantially higher than functionally comparable bilateral bone conduction hearing support devices available at approximately 280–330 USD. Prospective buyers seeking medically supervised hearing rehabilitation should consult a qualified audiologist and consider certified hearing aids. Those specifically seeking the GMT bone conduction approach should weigh the cost difference carefully against the absence of verifiable performance data.

References

[1] FILLTUNE CLEAR - Official EC Store - https://filltune.official.ec/items/127890559 - accessed 2026-05-07; current retail price 220,000円 (tax inclusive)

[2] FILLTUNE WeCLEAR - Technology Page - https://filltune-weclear.com/technology.html - accessed 2026-05-07; manufacturer technology claims, MHLW FY2013 clinical project background

[3] Kibidango - FILLTUNE CLEAR 2024 variants crowdfunding campaign - https://kibidango.com/2530 - accessed 2026-05-07; 2024 crowdfunding variants, price tiers, and manufacturer claims

[4] eEAR-BC-HPH-Pro - XBD-Global product page - https://xbd-global.com/products/eear-bc-hph-pro-bone-conduction-hearing-aid-headphones-military-grade-bluetooth-noise-cancelling-dsp-amplification - accessed 2026-05-07; bilateral bone conduction hearing support device at 279.98 USD

(2026.5.9)