Background

I've always enjoyed a good set of over-ear headphones. After I got my first real job, I purchased a pair of Sennheiser HD 569. These are closed-back headphones, meaning some noise from the environment leaks through, but not much due to the material in the way. After those got worn down, I bought another pair. After those got worn I switched to the HD 599. I switched primarily because they seemed to have higher quality ear cups. The HD 599 is an open-back headphone. When there's nothing playing through them, I can hear like I'm not wearing any headphones, I get all of the environment noise. This didn't bother me so much, because I had a nice, quiet environment. I subsequently bought 2 more pairs of HD 599. One went to my wife, one is sitting in a box, waiting for my current ones to wear out. I would say the HD 599 are currently my favorite headphones. The only thing that makes them better than the HD 569 is the higher quality ear cups and perhaps the fake leather headband. I do prefer the closed back. Since I've purchased the Momentum 4 headphones (about 3 months ago?), I've used them every single day. Although, I might change that soon...

Quick notes

The audio quality is what I've come to expect from the other headphones listed.

The case that the headphones come with is good.

If you've come via a search engine with a query to see if these are better than Sony XM5 or other headphones, I cannot answer that for you.

I also can't give an opinion on battery life, because these are my first wireless headphones.

Noise cancellation

I bought these headphones thinking that Active Noise Cancelling (ANC) was largely a consumer gimmick and the technology wasn't anywhere close to producing results. I was pleasantly surprised when I tested them out. I couldn't hear the ceiling fan, the shower, the dishwasher, and some other "distant" noises. My primary reason for buying these headphones was to remove the sound of my neighbor's dog barking all day, but these headphones did not do that. It also does not remove human speech. Yet I was still impressed enough to not return them during the return period. When walking by moving air, that sound is amplified in the headphones. This headphone's "transparency mode" is unpleasant to me. Supposedly this is where outside noise is allowed inside by reducing the amount of ANC. To me, it sounds like whatever the exterior microphones are picking up is then played through the headphones at a non-realistic volume.

Gestures

According to my podcast app, I listen to about 60 hours of podcasts per month. I also listen to a good amount of electronic music. Headphone "gestures" are a user interface for player controls and headphone specific controls via touches on the outside of the right ear cup. I absolutely love them. I primarily use them to skip advertisements and songs that I'm not feeling or change the volume. The Momentum 4 also pauses playback if the sensor in the top of the right ear cup doesn't detect heat or whatever. At first I didn't like this, but I like it now.

Using the integrated microphone

(I'm writing this from memory, so I don't plan on using all the technical names, because I haven't memorized them and don't want to be corrected.) The Momentum 4 has integrated microphones.

I see it as potentially false advertising that it is not noted that when using the microphone the majority of the important headphone features are not present. This is because a different Bluetooth (profile?) is used. The features not present in the profile with voice include ANC and audio quality related codecs/whatever. Apparently the bandwidth for the spectrum allocated to Bluetooth isn't large enough to transmit/receive all of the information required when voice is added. While doing a Discord call and playing any video game, the audio quality for the video game is so bad that it's not worth having on. The call voice sound is okay though. Still worse than my HD 599 and USB microphone setup.

This is 100% unusable as a Bluetooth gaming headset. Phone/video calls are okay, not great.

Bluetooth

I turn off Bluetooth for every device when it's not being used. These headphones require that if you want any sort of positive user experience. In my experience, most Bluetooth devices are not user friendly at all. I would never expect my parents to be able to troubleshoot these headphones. They would likely give up and never use them. There are so many bugs and non-intuitive workflows that I won't get into, but note this is the biggest pain point for these headphones and many other Bluetooth based devices.

I don't think this is all Sennheiser's fault. Poorly developed Bluetooth implementations go both ways, meaning my other devices can have nuances that cause problems. I personally feel that consumer products fail as a whole on delivering a user friendly Bluetooth experience.

Bluetooth adapters

For those of you who think something like the Creative BT-W4 can solve this Bluetooth problem, here is my experience. I tried to use the Momentum 4 when I was playing Apex Legends and on a Discord call. It did nothing to help, due to the Bluetooth profile change. However, I thought it was a nice Bluetooth adapter, but I don't need an adapter.

Bluetooth status messages

For the Momentum 4, there are frequent and LOUD (probably max volume) Bluetooth status messages. They sound like a speech-to-text female voice. This happens on every Bluetooth connection, disconnection, pairing, and more. My personal least favorite is the CONNECTED announcement which deafens me before anything plays through the headphones.

In the Momentum 4 manual, it says you can turn these off. I emailed customer support about this, here is the exchange.

Me:

In the Momentum 4 manual, it says I can adjust the settings for the voice prompts via the app:

Via the Smart Control app, you can adjust settings for the voice prompts and sound signals (> 34).

Customer support:

This feature has not yet been added it will in future firmware update.

Me:

Can I get a date or approximate date? It's odd that it's already in the manual.

Customer support:

Its  a feature that will be added via a firmware update. The Team is working on getting this released as soon as they can. No date has yet been announced 

That has been in the manual since I bought the headphones several months ago. You can draw your own conclusions from that interaction.

Unacceptable bugs

The first bug is the most obvious. The Momentum 4 can connect to two devices via Bluetooth at once. When a notification comes on one device, like your phone, it will pause the one you are currently listening to, play the sound, then go back. In theory at least. In my experience, I'll be listening to music on my personal desktop, then a Slack notification will come in on my work computer. I'll hear the Slack notification all crackly and unpleasant, then it'll take a few seconds to switch back to the personal desktop, and bombard me with a sound not unlike a on/off crusty microphone gamer raging that was relayed through a cheap walky talky. It will go on until I disconnect and reconnect.

The second bug is less obvious. I use a personal desktop. It primarily runs Ubuntu Linux, but it also dual boots into Windows. If I'm connected to my personal desktop when it's running Ubuntu, then reboot into Windows, the headphones will go into a connecting/reconnecting loop rapidly. Same with the other way around. This is probably due to a Bluetooth thing where the address is the same, but some asset saved from pairing with the operating system is not. However, this shouldn't cause a rapid connect/reconnect loop. Seems like a small software update could fix that.

The third bug is dumb. Sometimes, the headphones will refuse to pair with a previously connected device. According to the Smart Control App, I only have 5 previously connected devices, so I'm not over the limit, which I think is 8. It's seldom, random, and annoying to forget & re-pair.

The fourth bug is annoying. Sometimes on connection, the headphone's volume will be muted, but whatever's outputting to your headphones will not be. I need to use a gesture to turn on my headphone volume to hear anything. It is random but fairly often.

This last bug was the last straw and made me write this Reddit post. It started this week. Sometimes, the audio will be extremely patchy and unpleasant similar to the more dramatic description in the first bug. It is seldom and random, usually happens on reconnect but sometimes in the middle of my music. The only solution is to power off the headphones and try again. After powering off, I typically hear about 1 second of clear audio from whatever I am listening to. This makes me think there was some sloppy coding around a buffer. I think this is foreshadowing the early death of these headphones.

Headphone jacks

I miss the ubiquity of headphone jacks. They are simple and reliable. After I got the Momentum 4, I upgraded my phone, a Pixel 4a to a Pixel 7. This is because the trade-in value for the Pixel 4a was $300 when trading in for the Pixel 7. The Pixel 4a was purchased for $350, so I thought it was quite the deal. If I was trading in for any other phone, it was $70 I think. The Pixel 4a had a headphone jack, the Pixel 7 does not. The only thing I enjoy with the Pixel 7 over the 4a is the better camera, but reflecting back on that decision, I would rather have a headphone jack.

Conclusion

If I could go back in time, I would not trade in my Pixel 4a and not purchase the Momentum 4. I want the Momentum 4 to be the best it can be, mostly because I'm already $350 dollars in, but also because I like the idea. I've submitted most of this feedback to via the Smart Control App's feedback feature, but I don't know if that's similar to screaming into the void or not.

Would I recommend these headphones? No. But maybe you value things differently than I do or don't mind the Bluetooth troubleshooting. It might be worth it for you. Please note these headphones cannot be used as a gaming headset if you are doing a voice call at the same time.

All headphones I've just mentioned are on sale right now for a great price on the official Sennheiser website. If you plan on getting a pair, check out microphone attachments for the HD series headphones. Mine are from 3rd parties, not official, but the utility is fantastic for voice calls. I am not affiliated with Sennheiser in any way.

Have any questions? I'll try to answer.

Edit:

I didn't introduce the Smart Control App. It's the mobile app for these headphones. It's slow and don't really do anything notable. I primarily use it to delete Bluetooth connections and update firmware. Updated firmware is important to me.