AFM Product Review: Swim MP3s

By Courtenay Verret – August 1, 2013

Swimming is a lonely sport.

It is lonelier still when you’re a long-distance swimmer eking out hour after hour in the water, chasing that black line down the pool or swimming into the open-water abyss.

For many, swimming can be meditative—a chance to sort through one’s thoughts. I am one of those swimmers; I enjoy the stillness of the water and the sound of my hands catching the surface. But, I’ll be honest: When I’m averaging up to 10 hours in the water each week, the silence can sometimes be deafening.

It is in that spirit that I tested out two swimming MP3 products this summer while training for the Colin’s Hope Got2Swim Lake Austin 10K. After researching swim MP3s online, I settled on two products to test: the Finis Neptune Underwater MP3 Player and the X-1 Interval 4G Waterproof Headphone System.

The Neptune is an all-in-one MP3 unit that features bone conduction audio. This means that, rather than using earbuds, the unit has two speakers that rest on your cheeks and conduct the sound through your jawbone to your inner ear. Sounds freaky, but it’s not a new concept: This type of transmission is also used in hearing aids.

The Interval, on the other hand, is actually a waterproof case that houses a fourth-generation iPod Shuffle. It is equipped with earbuds that suction into the ears and exterior controls that allow operation of the iPod.

What’s In the Box?

The Neptune comes with a USB charging cable, instructions, and a mesh carrying case.

The Interval comes with instructions as well as several different sizes of earbuds, giving the user options for getting the right fit.


The Neptune comes with detailed instructions on how to sync your music on the device. I highly recommend that you read and follow them. The downside to set-up, if you are a Mac user, is that you must first convert your sound files into MP3s rather than Apple’s AAC format. This is somewhat time consuming, although the instruction booklet lays out the process in detail, making it relatively painless. Once your MP3 files are ready to go, you simply connect the Neptune to your computer via the USB cable (which charges the device as well) and drag and drop the sound files into the player, which has 4 GB of storage (approximately 1,000 songs).

Set-up for the Interval revolves around the iPod shuffle. Like all Apple music devices, the shuffle must be synced with iTunes in order to transfer music (the shuffle has 2 GB of storage). Once the music has been transferred, simply open the Interval case, connect the iPod shuffle, and close. It is recommended that, before you use the Interval with your iPod shuffle, you hold the case underwater to ensure there are no leaks.


The Neptune’s controls are easily navigable. There is a Power On/Off button on the top right, and you can advance or reverse songs with the controls on the left side of the device. There is also a Play/Pause button on the left-side speaker.

There are a lot of options for playback with the Neptune; you can add songs to your “Favorites,” play all songs, or listen by artist. There are “Shuffle” and “Repeat” controls, as well as a sound equalizer.

The Interval controls are simple and straightforward:  Once your iPod is charged, turned on, and properly inserted in the case, simply operate the controls on the Interval as you would on your shuffle. It is easy to advance and reverse songs; however, iPod shuffle users are limited in how their music plays back:  Random shuffle is the only option.


Both the Neptune and the Interval clip on to the back of the goggle strap; the position for both devices places the controls within easy reach. The Neptune’s speakers are attached by wires that wrap around the sides of the goggle strap and then clip on to it, so that they rest flat against the cheekbones. The Interval has wires that attach to earbuds; these can also be wrapped around the sides of the goggle strap to take up slack but, in my opinion, this is an unnecessary step.  Securing the earbuds in your ear before getting into the water helps increase the suction.

Sound Quality

The bone conduction technology of the Neptune was a new and fascinating concept to me, and I was anxious to try it out. After securing the speakers to my cheeks, I turned on the device and could hear the music playing. Once I got underwater, the sound was louder and clearer. It worked just as advertised.

That said, I was initially disappointed in the Neptune’s quality of sound: I can only describe it as being “tinny” as opposed to “full.” Or, to put it another way, there was too much treble and not enough bass. I adjusted the sound equalizer, which helped somewhat, but it was still not of the quality I am typically used to with, for example, my iPod.

Eventually, however, I adjusted to the sound and, heading into my second hour of swimming around the lake, it was no big deal.

After testing out the various earbuds for the Interval to see which size fit the best, I achieved good suction in my ears and turned on the unit. The sound quality was full and wonderful—what you would expect when listening to an iPod on land. However, over the course of my long swims, I several times experienced an issue with the earbuds, which ultimately reduced the quality of sound (see the following “Performance” section for details).


The Neptune’s sound performance holds up well in water. The sound quality, while not “full,” is consistent; I never once had an issue of being unable to hear my music or needing to make adjustments. The longest I used the device at one time was four hours, and I experienced no battery issues. In fact, I was able to use the device the next day after forgetting to charge it overnight.

The Interval, on the other hand, is at the mercy of the iPod shuffle’s functionality. To that end, I learned quickly that my iPod shuffle was somewhat finicky, which required me to stop and open the case (risking water getting onto the device) to reset the unit. This has nothing to do with the quality of the Interval, but is something that users should be aware of.

The sound quality of the Interval was hands down the best between the two devices; however, after about an hour of usage—or if I stopped to refuel and took out my earbuds—I had issues with suction. This meant that sometimes I could hear better in one ear than the other, or that the sound was otherwise distorted. I tried to solve this issue by squeezing all of the excess water off the earbuds on my rest breaks. Sometimes this helped, but not always.


I was very happy with both the Neptune and the Interval. Both devices are of good quality and perform as advertised. Those who already own an iPod shuffle may wish to save themselves the set-up time and go with the Interval case. They’ll also end up saving some money, since the Interval retails about $60 cheaper than the Neptune.

For those who want more control over their music listening experience, the Neptune is the obvious choice. With the ability to play by favorites, artist, or on random or shuffle, there is more opportunity to customize music choices.

Both devices have their pros and cons for sound quality. The Neptune is consistent, requires little fuss once the speakers are properly positioned on the cheeks, and allows the user to make some sound adjustments through the equalizer. Sound purists, however, will likely prefer the quality of the iPod shuffle inside of the Interval case. Although its sound is (in my opinion) superior to that of the Neptune, swimmers who plan to be in the water for a long time should be aware that loss of earbud suction is a distinct possibility, which can diminish the sound and experience overall. Those who swim shorter distances, or who have no need to take out the earbuds in the middle of their swim, are likely to have fewer issues with suction loss.

Either way, swimmers can’t go wrong with either purchase. Both devices offer them a break from the monotony of the water and a beat to which they can get their groove on—which is sometimes all the motivation needed to push through that last lap.


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