Just how large is the “true wireless” (TWS) earphones category? Glad you asked. With industry estimates that Apple has already sold over 400 million pairs of AirPods, it is safe to say that the competition within the category is for second place. And there are a whole lot of players vying for that spot.
Sony and Bose stake their claim with better ANC (Active Noise Cancellation), while Master & Dynamic and Bowers & Wilkins claim the boutique space, which leaves an opening for Sennheiser to compete by offering a mix of improved sound quality, strong ANC performance and a long list of features.
The Momentum Line
The Momentum True Wireless line from Sennheiser has been their entry into the mainstream wireless earbuds category whilst models like the Momentum Sport compete against other dedicated Gym buds. There is some confusion as Sennheiser uses the Momentum branding for both in-ears and over-ear headphones. The Momentum 4 Wireless is a headphone whilst the Momentum True Wireless 4 (MTW4) is an earphone.
As an aside, “True Wireless” (TWS) for an earphone means that there are no wires whatsoever. A Bluetooth wireless earphone could have a wireless connection between the phone or tablet and one of the earbuds, and a wire connecting that earbud to the other earbud. But a True Wireless earbud maintains an independent wireless connection between the playback device (e.g., phone or tablet) and each individual earbud.
Our regular readers may question, “Why now?” for this review as they are, perhaps, remembering our review of the earlier over-ear Momentum 4 more than 18 months ago. The reason is that the Momentum in-ear was not released at the same time – it only became widely available in mid-March of 2024.
We reviewed its predecessor, the Momentum True Wireless 3 nearly two years ago and found it quite good in many respects. With updates to firmware and the app, it is one of the few wireless in-ears that arguably got stronger as it matured in the marketplace. That is one of the advantages of purchasing Sennheiser products: they are more engaged with fixing and improving existing models than most of their competitors.
The MTW4 builds on the earlier model with Sennheiser claiming to have improved its core features, along with improved sound quality and battery life in the new model as well as making them a bit more comfortable to wear for longer listening sessions.
Build Quality
Outwardly, you’d be excused for thinking not a lot has changed aside from a different color scheme. The review pair is the copper black colorway with the case sporting a copper/brown twill case. Other color options are white silver with a gray twill and black graphite with a charcoal twill case.
The outer shell is metal while the inner is polymer with a rubber ring fitted between the two that Sennheiser refers to as ear-fins. The ear fins provide three slightly different fit options with the mid-sized installed by default and small and large options provided in the case.
Combined with the four tip sizes, the earpieces can be made to fit most ears rather comfortably. One thing I noticed right away is that the tips now sport a screen to exclude dust and debris from the nozzles.
The tips are washable as well so keeping them clean is now a bit easier. The earpieces themselves are IP54 rated, making them water resistant enough for gym wear. But please don’t take them for a swim.
The case is also almost indistinguishable from the MTW3 other than color, so much so that the 3s will fit in the 4s’ case and vice versa. The dimensions are the same externally as well, so other than color options, you’d be hard pressed to know the difference. Like its predecessor, the case is not IP rated so avoid getting it wet.
Internally, it’s a very different story. The drivers in the MTW4 are siblings with the drivers in Sennheiser’s high-end IE 600 and 900 wired earbuds and members of Sennheiser’s TrueResponse Transducer family, but have been tuned specifically for wireless use. Wireless earphones need easy to drive solutions in order to extend battery life and allow use of lower powered amplifiers which tend to fit in small spaces better.
So whilst the driver is similar to those in the IE series, the impedance is a bit lower and sensitivity likely a bit higher.
Features
Bluetooth has been upgraded to 5.4 using Qualcomm’s S5 version 2 chip and the antennae have been redesigned as well for better connectivity and sound. Initially, this will allow 16-bit/44.1kHz lossless audio via the aptX lossless codec. AptX adaptive, AAC, and SBC protocols are also supported for those with devices that do not offer lossless support.
It is important to know that by default the MTW4 is not in lossless mode or even high resolution mode, so those who want to take advantage of higher audio quality will need to use the audio resolution setting in the app and set it to the highest supported level.
One nice feature is even if set to lossless, the MTW4 will drop back to Adaptive or AAC if the source does not support the lossless codec. This prevents bricking the earbuds by selecting an unsupported mode.
Bluetooth multi-point connectivity is supported as well with the earpieces able to store 8 different source devices in memory. This may come in handy if you like to swap between connected devices, like maybe a phone, a computer and a TV.
There is an “eco” mode hiding in the settings that allows users to disable the lossless codecs to improve battery life when using the MTW4 for phone calls or audiobooks and a gaming mode for lower latency that allows for stereo music and mono chat.
Battery life is rated at 7.5 hours with ANC enabled and a bit more than 9 hours with ANC turned off. Using the “eco” mode can extend that a bit further.
We found Sennheiser’s battery ratings to be a tad optimistic at normal listening levels but close enough to the mark that it may be a sample variance as my results were within 5% of the claimed battery performance.
When the earpieces do need recharging, the case can provide roughly three full charges before needing to be plugged in via its USB Type-C port or wirelessly charged.
Be aware that a battery saver mode slows charging and prevents the earpieces from reaching 100% charge when enabled. This is good for the longevity of the earpieces as lithium batteries are rated for a certain number of charge cycles and last longer when avoiding extremes (0% or 100% charge).
Using the battery saver charging profile will maximize the earphones’ battery life. But it does mean that even after charging over-night the earpieces will show 80% charge in the app with the case at 100%.
This is by design, but can be overridden in situations where the additional play time is worth the additional stress on the battery.
Smart Control App
I have already made reference to the Sennheiser Smart Control app several times and find the app to be one of the more robust on the market, The app incorporates all of the expected features and several most other competitors don’t offer.
Under the “Device” heading, EQ settings offer bass boost and podcast presets, as well as a 5-band customizable EQ which is fairly standard. But in addition, you’ll find a fit test and sound personalization functions that allow more tailored customizations to the listener.
ANC mode offers an anti-wind setting for outdoor use along with adaptive ANC for routine use. Transparency mode allows the user to customize exactly how much of the environment gets in and also allows for automatically enabling transparency during phone conversations if desired.
Touch controls can be re-assigned or turned off altogether if desired. The last setting under the device heading is sound zones which allows the user to create sound profiles for home, office, etc… and the earpieces will automatically enter that mode when the source device detects a specific network or location as defined by the user.
In addition to the device heading, a “Settings” heading hides settings you might need but are not likely to need daily. Here firmware updates, audio resolution settings, battery settings, voice prompts, and auto-accept call are all options on the menu.
The “Discover” tab is basically for marketing additional Sennheiser products. There is also a “Tiles” section under settings that will allow users to hide features they don’t use to streamline the app.
It will not however let you hide “Discover.”
Sound Quality
As much as I like the Smart Control app, the truth is if the earpieces don’t stay connected and sound good, the app is not going to matter. I found the MTW3 fell a bit short of the Sony and Bose offerings on release but it improved with a couple of firmware updates that helped keep it in contention with those models it initially lost out to in my early testing.
Knowing that Sennheiser had to scramble some to update the MTW3, I expected a more refined release in the MTW4. I connected the MTW4 to my OnePlus phone since it has aptX lossless capability and queued up my playlist.
Sub-bass is mildly elevated with a center around 50Hz and a slow decline to either side of it giving the lows good rumble. There is some texture at the lowest point, but it gets notably more textured once over about 200Hz as the signature moves into the mid-bass.
The mid-bass has good clarity and speed with a touch of warmth but lacks the emphasis given the sub-bass. I find this tuning quite nice as it doesn’t get wooly or allow the mid-bass to over-take the lower-mids and relies on the sub-bass to add the extra authority needed for big bass hits.
Some may find the mid-bass to sound mildly recessed as it moves into the lower-mids but I think it can more accurately be defined as neutral. There is increasingly an expectation of elevated bass as normal and the MTW4 bucks that trend. Good on you, Sennheiser!
Lower-mids are at about the lowest part of the shallow ‘V’ tuning of the MTW4 but still are able to give lower voices good energy and clarity. Guitars have good growl and enough sharpness to sound realistic. Lower strings need a touch of EQ to reach their full potential but as frequencies go up, so does the energy.
The midrange overall is rather neutral with good detail and clarity. Female voices stand slightly forward of their male counterparts due to an upper-mid lower treble lift.
The lift is mild enough to prevent fatigue and nasal voices while still helping with vocal timbre.
There is some grain to the treble as, after an early lift, it drops back quickly only to resurge. So the 5kHz band is notably below that of the 2kHz or 8kHz band by comparison.
The result is a treble that emphasizes vocals but downplays percussion snap comparatively. Cymbals have a bit less energy than perfect to my ear.
Overall, it’s a safe tuning that is listenable for long periods without fatigue but treble lovers will lament the loss of a bit of detail and energy in the treble.
I don’t expect a huge soundstage on a closed-back ANC in-ear and the MTW4 fit that expectation as stage is fairly intimate and a bit wider than deep. There is some height in the mix but it is limited when listening to tracks like “So lonesome” by the Cowboy Junkies.
Echoes are neither as far away nor as well defined as with an open-back headphone or something like the Audeze LCD i3.
Still, within these expectations, the MTW4 does an admirable job of seating the orchestra without overlaps or gaps and instrument separation is better than expected. Imaging is solid with movements easily tracked and positions well defined.
Overall, the MTW4 is a rich, full-bodied sound that aims more at listening for pleasure than for studio use which seems a wise decision considering the use case for most TWS in-ears.
Noise Cancellation
ANC was good on the MTW3 but fell a step behind both the Sony and Bose offerings in my testing so it was no surprise to see Sennheiser focus on improving ANC performance of the MTW4. Microphones, 3 per ear, are a new design and the Qualcomm chip used in the MTW4 now supports adaptive ANC with a more advanced algorithm for sorting out what to keep and what to block.
I did find that the MTW4 did a good job on most droning noises but still struggles with higher pitched fast noises. None of the in-ears tested have been able to block out 100% of those noises, but Sony and Bose are still the ones to beat in this test.
The Sennheiser is a bit better than the Apple AirPods Pro 2 though so it’s among the better available options if not top on the list. The Anti-wind setting is particularly useful and worked well when using the MTW4 outdoors.
Sennheiser did a good job of not letting the ANC change the signature or mute the dynamics of the MTW4 which is another common problem among ANC models. There is a very slight thickening of the lows with ANC enabled, but dynamics remain strong and there is no loss of treble clarity.
The ANC function for phone calls has been improved as well and did a good job of rejecting outside noise heard by those on the other end of the call. I was told that a future firmware update will allow the Qualcomm chip to learn voice patterns and will help improve call quality further as the one issue I had was the person using the MTW4 can sound a bit muted as it struggles to sort out voice from background at times.
Again, I think the noise rejection was in the ballpark with Bose and Sony with the MTW4 falling between the two, slightly ahead of the QC Ultra but slightly behind the Sony XM5.
It will be interesting to hear the difference if that firmware update becomes available and see if the MTW4 can leapfrog the XM5.
There are several promising features that are awaiting firmware updates to enable in addition to the “voice learning” in ANC, Auracast, LE Audio support, and 24bit/48kHz lossless are all things that Sennheiser has stated will be available at some point on the roadmap.
This is a nice hedge against obsolescence and with Sennheiser’s track record of delivering on previous updates I think they are highly likely to happen. Still, one can’t rely on to promises so time will tell how many of these come to market in a timely fashion and if the MTW4 becomes stronger when they do become available..
Final Thoughts
My previous statement about promised updates may give some the idea that a “wait and see” approach is needed here but that isn’t the case at all. The Sennheiser MTW4 is a strong choice as is in today’s crowded space for those who want top shelf ANC performance in a package with a richer, fuller sound than the Sony XM5.
These two competitors share almost everything except a sound signature and there, they couldn’t diverge more. The Bose ‘phones fall somewhere between the two in signature with a bit less bass power and a bit more midrange presence compared to the MTW4 while remaining a bit more V-shaped compared to the Sony XM5.
The great thing is we now have 3 top level performers with signatures that differ enough that one of the three is bound to fit every listeners’ needs and sonic tastes.
I will even make the argument that if purchasing one of the three, I’d try the MTW4 first as it has more customization options than either of the other two and will likely only get stronger as additional features arrive via firmware.
Where to buy: $299 at Amazon
Related Reading:
First Listen: Sony WF1000-XM5 TWS – The New King of Wireless ANC Earphones?
Audeze LCD i3 in-Ear Monitor Review
