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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-28 · 6 min read · Independent comparison
• MARLALL biggest strength: IP68 waterproofing plus 32 GB of built-in MP3 storage, so you can swim with music without a phone anywhere near the pool.
• MARLALL biggest trade-off: Bluetooth simply does not work underwater — the moment you submerge, you have to be in MP3 mode, and the mic needs drying after a swim.
• Retekess TT042 biggest strength: dual modes (pickup amplification and line-in) with 6 volume steps, aimed squarely at speech clarity for seniors and guided tours.
• Retekess TT042 biggest trade-off: just 8 hours of battery and no waterproof rating — it's a dry-land listening aid, not a pool device.
• Choose MARLALL if you're a swimmer, snorkeler or outdoor athlete who wants one pair for laps and workouts.
• Choose Retekess TT042 if you want mild hearing help during conversation, museum tours, or when watching TV through the 3.5 mm line-in.
The MARLALL S800 is built around one very specific job: letting you hear music while your head is in the water. The IP68 rating covers immersion, sweat, rain and dust, and the nano-coated sealed body is designed to survive pool and saltwater exposure. The catch is spelled out clearly by the brand itself — Bluetooth signals can't travel through water, so swimming happens in MP3 mode only. That's why the 32 GB of internal memory matters so much: it holds roughly 8,000 songs, and you load them over the magnetic charging cable, which also lets a computer see the internal storage for playlist swaps.
Outside the pool it behaves like a normal open-ear Bluetooth headphone. Bluetooth 5.4 gives you a stable connection up to 10 meters, with touch controls and a bone conduction driver covering 20 Hz to 20,000 Hz. The frame is silicone with titanium, weighing just 22.68 g, and the open design sits off your ear canal so you stay aware of traffic on a run or other swimmers in a lane. Battery life is listed at 30 hours with a 2-hour charge.
Buy it if you swim, snorkel, boat or train hard outdoors and want one device that covers laps and land. Skip it if your main need is hearing assistance in conversation or TV listening — that isn't what this is designed for. Also go in knowing the maintenance ritual: dry the microphone after a swim, otherwise calls suffer. And if you plan to take calls mid-swim, that won't work; Bluetooth audio and calls are dry-land features here.
The TT042 is an assistive listening system first and a headphone second. It uses bone conduction to send sound through your bones rather than into the ear canal, which keeps the ear open and avoids earwax buildup — no daily ear-tip cleaning, just a wipe of the smooth surface. That open-ear, hygienic design is a big part of why it's aimed at seniors and anyone who wants mild amplification without plugging their ears.
Its two modes are the real story. Pickup Amplification Mode turns the ear hook into a standalone unit that picks up and amplifies voices within about 1.5 meters — handy in a tour group or a one-to-one conversation, so you're not elbowing to the front. Line-in Mode takes an external source through the included Type-C to 3.5 mm cable, so you can run TV or other audio gear straight into it. Retekess notes the connector going into a phone or laptop must be a standard 3.5 mm TRS plug, which is worth remembering before you buy cables.
Power is a 200 mAh battery with up to 8 hours of use and a 2.5-hour charge, and a colour-changing indicator light shows on/charging status so there's no guessing. Six independent volume levels let you tune for a quiet room or a noisy one. Buy it if you want clearer speech day to day, on tours, or while watching TV, and you value simple controls and low upkeep. Skip it if you want a workout or swimming companion — there's no water protection here, and 8 hours is a day of light use, not a week of laps.
Side-by-Side: Which Should You Choose?
• Best for battery life → MARLALL. 30 hours versus 8 hours is a huge gap for all-day and multi-session use.
• Best for hearing assistance and speech clarity → Retekess TT042. Pickup amplification within 1.5 m is a feature MARLALL doesn't offer at all.
• Best for TV and external audio sources → Retekess TT042. Line-in mode with the 3.5 mm adapter beats a straight Bluetooth headphone for fixed sources.
• Best for storage and phone-free listening → MARLALL. 32 GB of internal memory means no device needed once tracks are loaded.
• Best for simplicity for older users → Retekess TT042. A power indicator light and 6 volume steps are easier to manage than touch controls.
• Best for running, cycling and general workouts → MARLALL. Bluetooth 5.4, 10 m range and a 22.68 g open frame suit movement.
• Best for low maintenance → Retekess TT042. No ear tips to clean; just wipe the surface.
In my opinion, most people searching this comparison should buy the MARLALL Swimming Headphones-Bone Conduction. It does more jobs — swimming, running, cycling, calls and phone-free MP3 playback — and the IP68 rating plus 30-hour battery make it the far more versatile pick. The only reason I'd point you to the Retekess TT042 is if clearer speech, tour audio or TV listening is the actual goal, because that's a job MARLALL simply wasn't designed to do. If you're a swimmer, MARLALL is the one I'd choose.
FAQ
how to bone conduction earphones work
how to use bone conduction earphones
Place the transducer against your cheekbone just in front of the ear, then connect your source. On the MARLALL you switch to MP3 mode for swimming since Bluetooth can't travel underwater; on the Retekess TT042 you pick either Pickup Amplification Mode or Line-in Mode via the 3.5 mm cable.
how to wear bone conduction earphones
Rest the band or ear hook so the driver sits on the bone in front of your ear, not inside the canal. MARLALL notes it works with swim caps and goggles; the TT042's ear hook sits over the ear and avoids earwax buildup because nothing goes into the canal.
are bone conduction earphones waterproof
Not automatically — it depends on the model. The MARLALL carries an IP68 rating for immersion, sweat, rain and dust, while the Retekess TT042 has no stated water protection and is meant for dry use. Always check the rating before swimming with any pair.
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