Definitions:

• Ambient/Passthrough: microphones are used to pass external audio to hear your surroundings. I’ll use “passthrough” as I feel it’s more descriptive, Sony calls this “ambient”.
• NC: Noise Cancellation.

WARNING! The Sony WH-1000XM4 may not be suitable for you if you have a small head: The headband doesn’t go that small.

Summary

• Very capable.
• Unnatural but enjoyable sound signature.
• NC is up there with the best. Atmospheric brown/pink noise can be heard with no music playing. Other headphones are almost silent.
• Head band too big for small heads!
• NC settings overly complicated but you can turn off smart switching.
• Voice activated passthrough is great. Handy for pausing music and hearing surroundings without using your hands.
• Touch panel volume control only allows a single step ≈3% per full swipe. You can swipe and hold to continue volume adjustment but this is slow.

App

First you need to install the app. It has a rating of 3.5/5 from 1.5k reviews on the Apple app store. It installs quickly suggesting small size which is a good sign.
It’s fine but could be simpler and more customisable. In practice you won’t use it that much. It was reliable with no connection issues.

Unboxing

The box combines plastic and card, a plastic covered wire tie is used for the 3.5mm cable and a piece of plastic for the USB-C cable. Please stop using plastic in your packaging Sony.
The case is fabric coated with a nice with loop and mesh pocket on the outside.
The case appears to be quite sturdy, durable and offers good crush protection.

Opening up the case reveals a neat package including a short USB-C cable, flight adapter and 3.5mm cable, each have their own section. I prefer a short USB-C cable as it’s easier to store and manage plus is neater to use with your laptop. Some may prefer longer but you can swap it out. The headphones are well protected with a non-padded but felt covered divider.

The headphones give you get an oozing of quality. The cup pivots are so smooth, like they’re on bearings and the hinges are smooth too. It’s a floppy mess taking them out due to the hinges and swivels. The left cup is on the right in the case and vice versa. It’s not a big deal and I’m sure it’s something that you’ll get used to. The headband has a ratchet mechanism that is easier to extend than to retract. It's too easy to extend and it has led to the headband being extended by accident.

The cups seem very well made but not as seamless as other headphones, the pads are slightly wavy at the top and bottom. The leather and padding is very soft making them more comfortable for long periods.

There are two buttons, “Power” and “Custom” and a touch panel on the right cup.

Inside the left cup is a proximity sensor. I don’t like how this is asymmetrical with the right cup, in theory producing a slightly different sound signature from right to left.

Putting the headphones on I noticed two issues one of which could be a deal breaker!

1. My head is quite small and the smallest setting was slightly too big for me so these may be too big for you if you have a particularly small head.
2. The ratchet mechanism is quite high on the band so you can’t hold the cans in your hand and use your index finger to adjust. You can hold above the cups to reach the upper part of the band, but this isn’t as natural as holding the cans where you want them and then adjust the band into place. There is a little raised dot on the back of the left cup to help you to identify left from right. I didn’t notice my fingers accidentally pressing on buttons as I put them on. The power button is hard to reach on the bottom, tt’s possible, but a bit awkward. It’s not going to be easy to put these on and turn them on at the same time as I find works well with some headphones.

I’m quite disappointed that the headband doesn’t go any smaller.

The clamping force on the Sony feels light. This spreading of weight and pressure makes the headphones feel very light, lighter than other ones.

Turning on requires a long press of the power button. They immediately went into pairing mode with what I thought was passthrough mode because the noise floor of NC is so high. The app took me through setup where it asked for my location as it can automatically change the mode of the headphones. Initially you can’t tell the app to always use your location and have to select “Allow when using app” later the phone asked if I wanted to always allow.

The app also took me through 360º reality audio. This took pictures of my ears and optimised Tidal (the music app I use). After that I had a prompt as to what software version was running. It wasn’t very clear what to do but I shortly noticed it was “Transferring the latest headphones software...” There is a noise cancelling optimiser process. Not sure what it does beyond optimising for the environment you’re in but I didn’t notice a difference and I wonder why doesn’t it just do it automatically?

Comfort

These pads are slightly larger and softer than their predecessor which should make them more comfortable. As above, the band doesn’t go small enough for small heads. As a result my left ear, if not positioned carefully would touch the proximity sensor and after a while became painful. This shouldn’t be a problem if you have normal sized ears and head. The cups are also quite shallow relative to other headphones. I never felt discomfort from the band or the pads.
Larger pads may make them warmer than other headphones and although I didn’t get sweaty, my ears did feel a bit clammy after an hour or two.

Multipoint/multiple connections

These headphones support multiple simultaneous connections e.g. Laptop and phone.
LDAC will be turned off which is used for Hi-Res streaming. LDAC is not available on iPhone.

Bluetooth pairing and connection

The pairing process was easy, without issue. The app quickly recognised the headphones. Unfortunately I can’t say it is completely rosy. I’ve had occasions where it appears to connect to my MacBook but I can’t select them as the audio output, shortly after, they disconnect. Nothing I did would fix this when I was able to connect and select other headphones. The only way I could then get this to work was to enable “Connect to 2 devices simultaneously”. Connection stealing is possible but very unreliable so you have to manually disconnect from one device before connecting to another. I can confirm that this is the cause of the issue mentioned above. In multipoint mode, connection stealing might be more reliable and you get a “Bluetooth device 1 replaced” confirmation. The downside is that you can’t use the higher quality LDAC in this mode. When it does work, the earliest connected device is disconnected.

I found the range to be pretty average but nothing bad. I would have hoped for a better connection given the price and all that space to fit an aerial?! I get the same range with a pair of truly wireless earbuds!

Noise cancellation

With NC on you get an atmospheric brown/pink noise, it’s not that loud and sounds kind of natural but it’s something I don’t experience on other headphones. I turned my ultra quiet fan on to full power. I can only just hear the fan. The fan noise is kind of added to the atmospheric noise. This atmospheric sound isn’t necessarily a bad thing, it gives you a sense of spaciousness but it doesn’t give you the same reassurance of noise cancellation that other headphones do. Wind noise can be picked up by the microphones.

With general, less predictable ambient noise such as talking, I found the headphones would dull them but strange artifacts occurred. e.g. a change in the atmospheric noise. I found this distracting. Not something I experience with other headphones.

With simulated plane noise I noticed a whooshing sound that was more prominent than other headphones.

In a simulated cafe environment I found a fair bit of higher frequency atmospheric noise as well as seemingly less consistent noise cancellation than other headphones. I found the NC overall more distracting as certain sounds would cause weird artifacts, not be very well cancelled or cause more atmospheric noise. Just to clarify, I’m nitpicking, the NC is very impressive, I do find other headphones are more consistent but not necessarily better.

Random noises - NC vs NC off (not passthrough)

Handheld jigsaw outside my window: I actually found these slightly amplified the saw. With NC off I couldn’t hear it. With NC on, I could only just hear it. Low frequency noises were however completely cancelled which were pretty loud with NC off. This is similar to other headphones.
Keyboard: The thud of the keyboard is removed, but the “clack” isn’t.

I’ve heard a lot of people saying the NC on the XM4 is better than certain headphones. I can’t agree that is absolutely the case. They are virtually identical to other headphones I’ve tried. The XM4 does have the brown/pink noise that can mask (not cancel) some sound and this could make it seem like they are better. I have even gone so far as to have one cup of one headphone on one ear and a Sony one on the other. I wouldn’t base your purchase decision on this.

Passthrough/Ambient mode

On some headphones there is virtually no atmospheric noise, the distinction between NC and passthrough is obvious. Passthrough on those headphones is almost like you’re not wearing them, the passthrough is very natural and it sounds almost identical to real life. The Sony performed worse here. It cuts out some of the higher frequencies, especially sibilant sounds - hissing sounds such as those when you pronounce an S. They also add to that atmospheric noise. I also noticed that they amplify the rustling sound of your clothes if you’re walking and this can drown out other noises. This is a clear and distinct loss for the XM4. That said, if you weren’t directly comparing then you might not find this such a big issue, but it’s just a wow how natural passthrough is on some models. It really is very close to not wearing them. Overall, I found the passthrough mode made the environment sound more noisy than it actually is, providing a larger contrast on the Sony vs other headphones between NC and passthrough.

The Sony has a “Focus on Voice” setting. It’s good to have it but I found it a bit weird in that the atmospheric noise would change making me feel a bit queasy! It seems to think some noises are voices so it passes them through.

A standout feature of the Sony is the voice detection. They will pause your music and turn on passthrough mode. After 30 seconds they revert back or you can double tap. This is customisable between 15s, 30s, 1minute or not revert automatically. Detection sensitivity can be changed. “Automatic" will adjust depending on the environment, there is also high and low. A throat clearing will activate this feature, even in low sensitivity. I would like low sensitivity to ignore a throat clearing, you can turn this off. I would also like to see a 5 second delay. I found the activation to be reliable and was never triggered accidentally. One strange thing I did notice is that if you’re already in passthrough mode and start talking, then the voice detection is triggered and the headphones go into a slightly different passthrough mode. Perhaps it’s to optimise for voice but it just didn’t seem right to me.

When talking with these I found my own voice passthrough to be disconnected, you get that talking in your head experience. It’s not too bad but I felt they could do better. I didn’t feel it natural to talk with these on. Other headphones perform better in this area.

Custom button

By default this cycles through Noise Cancelling > Ambient Sound > Off. Long press for Noise Cancelling Optimizer. Switichng between three modes with the Sony feels like a chore. Just having NC and passthrough would be better. You can’t customise the three presses, you can only change it to activate smart assistant. A long press on the touch panel also activates the smart assistant.

Pressing “power” announces battery level. Long press (2 seconds?) will power on/off. This seems a too long for my liking but it stops you accidentally turning them on/off.

Touch panel

Controls are:

• Double tap: Play pause
• Swipe up/down [hold]: Volume control [continue increasing/decreasing]
• Swipe backwards/forwards: Skip back/forwards
• Long press: Voice assistant
• Long press with two fingers: Turn on/off voice detection
• Cover cup: Ambient/Passthrough (Music continues playing at low volume. This isn’t customisable so not good for audiobooks or podcasts which you would want to pause.

You can completely turn off the touch panel with the “Touch sensor control panel” setting.
When changing volume you get feedback tones which can be annoying. There is a setting “Notification & Voice Guide” but this doesn’t turn off volume tones which I think is important to be able to do. I couldn’t find a setting that would. This does turn off the NC mode announcement which makes it easier to tell the difference in sound because it’s not hidden behind the voice prompt.

Volume control takes several swipes, way more than feels reasonable if you’re making a big adjustment. It’s not smart, you can only change the volume 1 step with a full swipe, Sony takes maybe 10-30 swipes! I also found that I couldn’t always adjust volume accurately enough, either being slightly too loud or too quiet. You can swipe and hold for the headphones to continue changing the volume up/down but this is very slow. I feel this doesn’t work as well as other headphones where you can change volume varying steps in a single swipe, they almost feel like an analogue volume knob.

Smart controls

Taking the headphones off pauses music. Some headphones with this functionality will play audio that is paused when you take them off, and then pause when you put them back on. The XM4 paused audio stays paused and will not play when you put them back on.
Voice detection pauses music and activates passthrough automatically. This works well but can be an issue if you like to sing or hum along. You can touch and hold the touch panel with two fingers to deactivate “speak to chat”. Two seconds seems too long, I would prefer 1. You can come straight out of “speak to chat” mode by double tapping. Unpausing from your device also brings you out.
Ambient/Passthrough mode can be set automatically depending on location e.g. at home or on the street.

Call/Microphone quality

I tested by recording my voice, these performed fine but not quite as good as other headphones.

Audio/Video lag

No perceptible lag. Tested with an audio video sync test video.

Sound quality

I’ve mentioned the noise floor but noise cancellation isn’t everything, especially with music playing so you can’t hear the noise. There’s a certain level that noise cancellation needs to be, mainly to cancel loud sounds such as on a plane and general chit chatter and noise in a cafe or public environment. It’s about the whole experience.

I’m pleased to say these sound great. They don’t sound very natural but I think they sound pleasing and enjoyable. Bass is strong, controlled, doesn’t sound muddy but could be tighter, mids are clear and smooth, highs go all the way up with accurate sibilance that’s not harsh, the XM4 sounds airy. Instruments are accurately placed and the soundstage is wide. Cinematic, deep, low, rumbly bass is strong and all there. The XM4s are like a juggernaut, powering through long bass lines, nothing can stop them. But is the bass a bit too overemphasised? If it is, I’m sure you can dial it in with the EQ.

360˚ audio

You will need a streaming source that provides 360˚ audio tracks. These libraries are typically limited. Is it a gimmick? Actually, no it’s not, it does expand the soundstage in a sphere around your head. It’s a great experience and separates instruments in 3D space.

Analogue wired mode and Noise Cancellation

The 3.5mm cable supplied isn’t symmetrical. I assume the right angle end goes into the source but can be plugged in either way. Being 3.5mm on each end it should be easy to replace.

In wired mode The XM4 doesn’t have volume control, others do. The XM4 is effectively full volume, therefore you could have an issue if your source volume is too high or volume steps too wide. On a plane with so many headphone jacks, cabling etc. the signal coming out of the jacks can be quite noisy and you can hear it in headphones, especially if they’re sensitive. A trick you can use is to turn the headphone volume down (not possible with the XM4) and turn the source up so you get a higher signal to noise ratio. I’ve found some headphones filter electrical noise. I have been on a flight and able to hear electrical noise with other headphones turned off but with them on the noise was removed! I haven’t been able to verify this with the XM4.

Hi-Res audio

These have DSEE Extreme and LDAC so they’re [more] compatible with Hi-Res audio and in theory they should sound better than other headphones. I have a Hi-Res walkman which can take advantage of DSEE Extreme and LDAC. At this level of audio quality it’s difficult to hear differences in the music itself but you do hear better separation of instruments which gives the illusion that the music is clearer, well it probably is! It’s like seeing in 2D vs 3D, both have the same visual quality but you get that extra depth information that allows you to better estimate where objects are. It also sounds smoother. This is all very difficult to discern any difference. LDAC is not available on iPhones.

Battery life

5 hours for a 10 minute charge is very useful, they generally charge quickly.
I did an initial battery life test with: Multipoint off (single device connected), DSEE Extreme on, NC on. Listening to around 80% spoken audio (videos etc.) and 20% music at 50% volume. I only got about 22 hours until flat which is a far cry from the advertised 30 hours. A full charge took about 3.5 hours. I turned DSEE off and Multipoint on (LDAC off) (two devices connected, laptop and phone). I then got about 28 hours.
All of the following will draw significant battery:

• DSEE Extreme on
• NC on
• LDAC on, there is no specific setting for this, you need to turn Multipoint on “Connect to 2 devices simultaneously” which turns off LDAC.
• Speak to chat on

Complexity

The Sony has more functionality than others but this results in a more messy experience. Whether the added complexity of the Sony adds value or not I’ll just have to live with them for a couple of weeks… in the end I turned off the automatic NC/Ambient location detection. It would occasionally change mode when I want it to stay in NC and the automatic mode changing is distracting. I guess you will get used to how they will react and what you don’t like, you can turn off.

Conclusion

The headband is too big for small heads. They feel overly complex in operation. They are pretty comfortable (head size aside). NC is right up there with the best. They sound fantastic but don’t sound that natural, they are very enjoyable to listen to. Extreme deep bass is more present than other headphones. The voice detection is useful if your hands are occupied. There is the brown/pink noise floor that I don’t understand why it’s there. I prefer the more analogue style of volume control on other headphones with touchpads. They are a bit of a floppy mess when getting them out of the case. The lack of volume control in wired mode could be an issue for people that regularly jack into in flight audio. I don’t know if they filter out electrical noise.

Resources

Settings affecting battery life