Sennheiser Momentum Sport earbuds take your temperature the easy way

How badly do you want to know your body’s temperature while you’re exercising?

I’ll admit that’s not a stat I’d even considered caring about. Maybe it’s due to the early morning hour, or maybe it’s just that the blood that normally would be going to my brain instead is trying to stave off further transformation to a full-on dad bod. But I just don’t think about my core temperature at all when I hit the gym at 5 a.m. every weekday.

I see if the YMCA regulars are there, of course. I might say hi to friends. Even spit out a few complete sentences. But while I take seriously the frequency (and intensity, I guess) of my workouts, I’d never once thought to worry about my temperature.

The new Sennheiser Momentum Sport earbuds have changed that. Or, at least, they’re trying to.

The idea of “Sport” buds isn’t anything new. Not even for Sennheiser, which already has “Sport True Wireless” buds with an awkward name aimed at telling you exactly what they’re for. The Momentum Sport buds, thankfully, have dropped the “wireless” part of the name while still managing to, ya know, not have wires.

What they do have are sensors for tracking a couple of specific things that might or might not be important to your workout.

They also still play music and podcasts and stuff. The question, then, is, do you really need all this in a single package, for a rather hefty $329 or so?

And should they be branded Sennheiser at all? Perhaps not. There’s a lot here that reminds me of the way smartphone manufacturers (of the Android variety, anyway) occasionally team up with audio or photography brands to bolt on some features in ways that don’t always make sense.

We’ll get into all that.

The basics

Let’s just get the hard part out of the way: The Sennheiser Momentum Sport are not inexpensive earbuds. At $329 retail, they’re more expensive than all of our picks for the best earbuds, save for Master & Dynamic.

In other words, don’t buy these if you’re just looking for something to use for music or podcasts while exercising. There are plenty of less expensive (and still excellent) options for that — including from Sennheiser.

No, you’re going to get the Momentum Sport for the sensors. Specifically, you’re getting a photoplethysmography heart-rate sensor and a body-temperature sensor that Sennheiser says is accurate to within three-tenths of a degree.

It’s a cool option if you’re not the type to wear a watch during your workout. (And Polar’s Vantage V3 watch only does temperature while you sleep.) Or a chest strap. And if you’re not going to those added expenses, then forking over that much money for good earbuds and sensors may make a little more sense. It’s pretty obvious that the sensors add to the overall cost.

Earbuds as earbuds

We’ll get to the sensors in a minute. But if the Momentum Sport don’t work well as actual earbuds, then everything else is moot.

The Momentum Sport perform admirably. Mostly. There are some relatively minor complaints, in the scheme of things, though I couldn’t help but think “For $329 I really kind of expected things to not be quite so rough around the edges.” Not physically rough or anything — the Momentum Sport fit me really well right out of the box. (There are fins and tips included, though, so take your time and get a perfect fit.)

This was my first real exposure to Sennheiser as a brand. My daily drivers, when not testing other buds, are second-generation Apple AirPods Pro. So perhaps I’m just used to (or spoiled by) their integration.

Let’s start with the out-of-the-box experience. The only real surprise part was the case itself. It’s not horrible. It’s about the size you’d expect for a case that allows for wireless charging, which is how I prefer things these days. I get home from the gym, put the case on a conveniently located Qi charger, and that’s that until the next morning.

But there’s a little rubber flap that covers the USB-C port for wired charging that doesn’t quite seem to fit, until it does. Mine was sort of half-in, half-out, but eventually would fall into place. And most (if not all?) wireless earbud cases that I’ve ever used have some sort of spring to the case lid that helps keep them open or closed. Sennheiser has a magnet here that’ll keep things shut, but otherwise, the lid just sort of flops around and makes the case feel a little cheap.

Anyway, that’s a weird couple of misses right off the bat. It’s not awful, just not quite what I expected.

Otherwise, the case is fine. It has a decent soft-touch coating. The buds are held in by magnets that are strong enough, and it’s easy enough to fit left to left, and right to right. There’s enough space cut out so you don’t struggle to remove a bud — your finger should fit in there just fine. The buds are rated IPX5 for water (you can spray them, but maybe try not to), and the case is IPX4 so it can handle a splash.

Funny first impression: There’s a lot of color going on with the underside of these buds. One LED flashes for the connection — you’ll see red and blue pretty quickly. But there’s also a green LED in the left-hand bud for the heart-rate sensor. That’ll come into play in a minute, and not in a great way.

As these were my first Sennheiser buds, I needed to install the Sennheiser Smart Control app, too. You can, thankfully, use it without registering for a Sennheiser account. But if you want the ability to set location-based profiles — Sennheiser calls them “Sound Zones” — you’ll need an account.

From there, it was time for a firmware update. A fairly lengthy one, at that — nearly 30 minutes, all in. That’s probably not the sort of thing that will be required all that often, but just be prepared. (And seeing a separate notice for “updating sensors” was certainly novel.) I did all my testing on firmware 3.17.15, but 3.18.15 was available as of April 9, as I was finalizing this review. And not that color matters any here, but my review units were of the olive variety. (Which often looks more gray than anything, with a tinge of green.) The Momentum Sport also come in black and graphite.

Time to take a spin through the app. Front and center are the buds with battery info for them and the case, which makes sense. (Though that the buds are pictured with fins attached seemed a little weird, since they don’t actually come attached. So, what I’m wearing doesn’t look like what I see in the app. That’s a small thing, though.)

I’m not the sort of person who reads instruction manuals. And I can never remember if it takes two taps to go forward a track, or three, or whatever. But there’s a handy little “Controls” section in the app to remind me. Two taps to play/pause. Three to go to the next track. But … why is it telling me to tap my cheek? Is the app just … broken? Did someone screw up the design?

Nope. That’s a thing. Tap “near the earbud” instead of actually tapping the earbud. Why would you want to poke yourself in the cheek instead of tapping the earbud? It feels strange. I’m going to just tap the earbud like a normal person. But even then, as often as not, I would trigger a pause with two taps instead of the intended cycling through Active Noise Cancellation (ANC), Anti Wind mode, and Transparency. That’s annoying, and I definitely prefer the more definitive long-squeeze/click thing the AirPods Pro employ. If I were going to make these my go-to buds, I’d probably change the touch-and-hold option to cycle through ANC instead of controlling volume level.

There’s another section of the app that lets you customize all that tapping — including changing the sensitivity, which is something you might well want to do. (See my aforementioned hard time registering that third tap.) You can also change whether something works on the left or the right. That’s a good amount of customization, and I’m very much here for it.

You’ll also want to spend some time in the “Noise control” section. The Momentum Sport have three options here — ANC, Anti Wind, and Transparency. Tap into the settings for this section, and you’ll see a slider to change the level of transparency, but that only works when you’re in Transparency mode. It doesn’t change anything for ANC or Anti Wind, and that’s a little confusing when you’re in the app because you see it all the time, even in the other modes. (That’s really an app-level user experience complaint and not a complaint about how ANC works on the buds.)

In any event, here’s the bottom line: Sennheiser’s ANC is decent. Pretty good, even, And occasionally even too good. There’s no option to completely turn off any sort of ANC. So, I’ve found myself either going full ANC or using Transparency on its highest setting. (As in, where it lets in the most ambient sound.) But that’s problematic, too, because the Transparency mode is noisier than just not wearing the earbuds in the first place. It’s almost the opposite of the Anti Wind option, in that there’s a constant sound that reminds me of my central air-conditioning fan. (Or if you’re into photography, almost like a photo that had the ISO cranked up so high that the image is riddled with noise.) That’s not really how that should work. Your mileage may vary a little, though, depending on how much damage you’ve done to your hearing over too many decades of heavy metal shows.

And on the early firmware I kept hearing a fast, repetitive clicking sound that I’m pretty sure was the green LED firing to check your heart rate. It wasn’t audible once I had music or a podcast playing, and the last-minute 3.18.15 firmware update seemed to lessen this a good bit, but I could still hear it. Hardly a deal-breaker in any event, but just something to be aware of if you hear it, too.

The app has a decent five-band EQ that’s worth playing with. It comes with eight presets, or you can save your own. (Note that you’ll save over a preset if you’re not careful.) There’s a Bass Boost toggle that I didn’t prefer at all — increasing things in the EQ sounded better to me — and a Podcast toggle that thins out voices a bit. I’ll be leaving it off, too.

There’s an option in the main settings to switch “high resolution” 24-bit/96 kHz audio with aptX Adaptive. But unless you’re using one of a scant few phones — none of which is from Apple, Samsung, or Google — you can’t actually use it. (And that’s before we start to argue over whether you can tell the difference anyway.)

All that to say, transparency issues aside, these earbuds sound very good. And they should, given the price. It’s a different fit and feel than my old AirPods Pro, but these are buds I could very well see myself using every day and not just at the gym. Music is fat on the low end. Crisp on the high end. At no point would you listen to something with these buds and wish you had something better. It’s just that the noise cancellation leaves a little to be desired.

The sensors

Let’s go back to the reason why you’d actually want to buy the Momentum Sport — the two sensors tucked inside the earbuds.

That Sennheiser is able to do this at all is a pretty incredible feat, given the size of the hardware. By the way, the weight is manageable at just under a quarter ounce per bud. (That’s straight out of the box, without a fin attached.) That’s a little heavier than my AirPods Pro, and it was noticeable by the end of my regular 90-minute workout. Not bad, just noticeable.

There may be quibbles over the accuracy of temperature and heart rate via earbuds versus other methods, like a chest strap. I wouldn’t worry too much about that. If you’re getting the Momentum Sport because they can track those biometrics, then it’s more about the relative change and not the absolute temperature.

As for the fitness platform and integration, Sennheiser relies on Polar (you’ve perhaps known the Polar Pro watches) by way of the Polar Flow app. That’s maybe a little clunky, but it’s also understandable that Sennheiser didn’t want to build all the health stuff into its own app. (You can view real-time heart rate and temperature data in the Sennheiser app, but you can’t do anything with it there.)

The Polar Flow app itself is pretty underwhelming — it very much feels like a web wrapper in a lot of places that it shouldn’t as you’re setting things up. But it works, and I could connect to Strava and Apple Health easily enough. It’ll pass on exercise data to plenty of other services, too, like Nike+, My Fitness Pal, and a bunch more.

Battery life, as with most devices like this, was just fine for me. I’m never going to exercise for so long that I’d run them dry. On paper, they should last around 6 hours of continuous use, with the charging case getting you 24 hours of total time. I’ve used them the same as I have my AirPods Pro, which is to say I’ve exercised with them in for about 90 minutes, popped them in the case on the 20-minute ride home (by which point they’d basically recharged), then plopped the case on wireless charger when I’m back in the house. And I haven’t had to think about them more than that.

Here’s the important thing you need to know: As things stand today, you’ll need to use the Polar Flow app to track your workouts if you want to take advantage of the sensors in the earbuds. And I had to manually pair them before the app would see them. There are a plethora of workouts in the app, though curiously, it’s missing a basic one like an elliptical machine. (Which is what I do every day because I am old and my knees are old.) Do your thing, and then that data will sync back to Apple Health or wherever.

All this to say that if you really want to track heart rate — which is something you can already do with most any other fitness tracker — and temperature with the Sennheiser Momentum Sport, you’re going to have to work for it a little and likely change up your exercise app routine. Unless you’re already using the Polar ecosystem (and that probably means you already have a Polar smartwatch), in which case, have at it.

Should you buy them?

There’s a lot to like here. Sennheiser has crafted a pair of capable earbuds that can do something most others (all?) cannot do — track heart rate and temperature. They sound really good. They’re pretty comfortable. They don’t try to trick you into using spatial audio because they don’t support it. Bluetooth Multipoint is available should you want to connect to more than one device. And call quality is fine, though I did have to explain to someone why I was making an actual phone call instead of just texting. (Welcome to the future.)

Heart rate is easily available across all kinds of devices — if you have any sort of smartwatch or fitness tracker, it almost certainly already can measure beats per minute. Why, then, would you also need that in your earbuds?

It’s the temperature sensor that’s new here. But I’m also not anywhere near convinced that it’s not more than a gimmick — something novel by which Sennheiser hopes to sell these buds to a very specific niche. Inside the Sennheiser app, you’re told that “real-time body temperature reflects the balance between the heat your body produces and the heat your body loses.” The idea is that if you get too hot and don’t drink enough — which brings your temperature back down a little — it “can lead to earlier fatigue and decreased performance.”

Fair enough. But are these buds sensitive enough to make a difference? And, for that matter, are my exercises strenuous enough to even trigger some sort of warning that might lead me to adjust things in search of a more balanced workout? I honestly don’t know. My usual 90-minute workout inside the YMCA only increased my temperature about six-tenths of a degree. (And even then, it only showed around 98.1 degrees Fahrenheit. Take that for what it’s worth.)

I think it’s pretty clear I’m not the intended audience for the Sennheiser Momentum Sport. I’m not in the Polar ecosystem already. I don’t own a Polar fitness tracker, and I don’t intend to change ecosystems anytime soon. The vast majority of my exercising is done indoors, thanks to all the reasons that Florida likes to throw at me. (Heat, humidity, and the occasional bit of dangerous wildlife.) I’m probably not pushing myself to the point where my temperature is ever affected. Nor do I intend to.

If you’re outdoors, exercising so hard that you’re worried your body temperature could affect the quality of your workout, or are content using the Polar ecosystem to track things, have at it. These should serve you pretty well.

Those are a lot of caveats, though. So many that you sort of wonder why these weren’t just branded as Polar earbuds with Sennheiser instead of the other way around.