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We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-24 · 7 min read · Independent comparison
• SEWOBYE's biggest strength: it is a complete, standalone waterproof music system — IPX8 rated to 10 feet, 8 GB of internal memory for over 2,000 songs, up to 16 hours of playback, and short-cord earbuds designed to sit under a swim cap with no phone required anywhere near the water.
• SEWOBYE's biggest trade-off: it is not a Bluetooth headphone. There is no wireless connection, no microphone and no app. You load music by plugging it into a computer over USB and copying files across, and you operate the raised-ridge buttons by feel.
• Sony WH-CH520's biggest strength: effortless everyday wireless listening — Bluetooth 5, multipoint pairing with two devices at once, hands-free calling via a built-in microphone, voice assistant support, EQ customization in the Sony Headphones Connect app, and a battery rated up to 50 hours with a quick-charge top-up of up to 90 minutes from just 3 minutes on the charger.
• Sony WH-CH520's biggest trade-off: it has no water protection rating and no wired jack. It is a dry-land headphone for commutes, desks, travel and calls — not for the pool.
• Who each pick is for: choose SEWOBYE if your workout happens in water; choose Sony WH-CH520 if your listening happens everywhere else.
The SEWOBYE is a niche product, and it is unapologetic about it. Everything about the design points at one user: someone who wants music while swimming and does not want to risk a phone. The player is small — roughly 0.75 by 1.42 by 2.01 inches and 35 grams — with a clip-on attachment that mounts on a goggle strap or swimsuit strap. The control buttons have raised ridges specifically so wet fingertips can find them without looking, and once you have read the operating instructions, the intent is that you can operate the player by feel mid-lap.
The audio side is more capable than the size suggests. The internal memory is 8 GB, which SEWOBYE rates at over 2,000 songs, and the supported formats cover MP3, WMA, FLAC, APE, WAV, AAC-LC and ACELP — including lossless files, with no conversion software required. The gold-plated stereo jack is there to resist corrosion, which matters in chlorinated or salt water. Playback is rated up to 16 hours with about 1.5 hours for a full charge, so a week of swim sessions between charges is realistic. The IPX8 rating means submersion to 3 meters, or about 10 feet.
The short-cord earbuds are the detail that makes the whole thing work. Long cables tangle around goggle straps; the short cord eliminates that. SEWOBYE also includes one extension audio cord, so the same earbuds can be used for running, skiing, kayaking or surfing. In the box you get the player, the waterproof earbuds, two pairs of changeable earbud tips, the extension cord and a USB charging/connection cable. SEWOBYE backs it with a 1-year manufacturer warranty.
Who should buy it: lap swimmers, open-water swimmers, triathletes in training, and anyone whose workouts involve surf, spray or rain — plus runners who want a phone-free player. Who should skip it: anyone who wants Bluetooth, phone calls, streaming apps or wireless control. Loading music means connecting to a PC over USB and copying files into the drive that appears on the desktop. If that sounds like a chore, this is not your product.
The Sony WH-CH520 is the opposite philosophy: a lightweight on-ear wireless headphone designed to disappear into your day. The headband uses soft earpads, an additional head cushion and silent joints, which is Sony's way of saying you can wear it for hours without thinking about it. It weighs 1.4 pounds as a bundle, and the swivel design lets the earcups fold flat for packing.
The headline number is battery life: up to 50 hours of playback, and USB Type-C quick charging that yields up to 90 minutes of listening from a 3-minute charge. That combination is genuinely useful — it covers multi-day trips and long weekends without a charger, and the quick top-up rescues you when you have forgotten to plug in.
Wireless features are where it pulls ahead of a basic Bluetooth headphone. Bluetooth 5 with multipoint pairing means it can hold two devices at once, so you can move from a video on your laptop to a call on your phone without repairing. The built-in microphone handles hands-free calling without taking your phone out of your pocket. Voice control works with "OK Google" or "Hey Siri," and Fast Pair support helps you locate the headphones through Google's Find My Device app.
The bundle includes a hard carrying case in addition to the headphones, which matters if you plan to toss them in a bag. Who should buy it: commuters, students, remote workers, podcast listeners and anyone who takes a lot of calls. Who should skip it: swimmers and anyone who needs water resistance, a wired connection, or active noise cancellation.
Side-by-Side: Which Should You Choose?
• Best for swimming and water sports → SEWOBYE Waterproof MP3. IPX8 to 10 feet, short-cord earbuds, no phone needed.
• Best for battery life → Sony WH-CH520. Up to 50 hours versus SEWOBYE's up to 16 hours.
• Best for phone calls → Sony WH-CH520. Built-in microphone and voice assistant support; SEWOBYE has neither.
• Best for carrying your own library without a phone → SEWOBYE Waterproof MP3. 8 GB and over 2,000 songs stored on the device itself.
• Best for switching between laptop and phone → Sony WH-CH520. Multipoint pairing with two devices at once.
• Best for sound tuning → Sony WH-CH520. EQ presets and custom profiles in the Sony Headphones Connect app.
• Best for a long run or wet-weather workout → SEWOBYE Waterproof MP3. The extension cord lets the same earbuds move from pool to trail.
• Best for all-day comfort on land → Sony WH-CH520. Lightweight build, soft earpads, head cushion and silent joints.
If I had to pick one for myself, I would buy the Sony WH-CH520 — but only because my listening happens on dry land, and its multipoint pairing, microphone and 50-hour battery cover the way I actually use headphones. If you swim, that logic flips completely. The SEWOBYE is the only one of the two that can go in the water at all, and its 8 GB of onboard storage and IPX8 sealing are exactly what a swimmer needs. In my opinion, these are not competitors — they are two different tools, and you should buy the one that matches where you listen. Check the current price on Amazon before you commit, since both sit in very different budget tiers.
how to make headphones music louder
Start with the source device volume, then check the app. The Sony WH-CH520 has EQ Custom in the Sony Headphones Connect app, which lets you adjust presets to your taste. The SEWOBYE has no app, so loudness is controlled by the player's own buttons and the file's recording level.
how to test stereo headphones
Play a track you know well and check that sound reaches both ears evenly, then listen for channel separation on a recording with distinct left/right instruments. On the Sony WH-CH520, confirm both earcups are working and test the microphone with a call. On the SEWOBYE, test with the short-cord earbuds seated fully in the gold-plated jack.
how to fix stereo headphones
First check the obvious: charge the device and reseat the connection. On the SEWOBYE, a loose or corroded jack is the usual culprit, which is why the gold-plated stereo jack matters in water use. On the Sony WH-CH520, unpair and repair the Bluetooth connection, and check the multipoint pairing if only one device is producing sound. The SEWOBYE carries a 1-year manufacturer warranty if the player itself fails.
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