True wireless headphones are a relatively recent development. Up until now, earphones had to be linked together by wire. As technology evolves, the manufacturers have been able to squeeze amplification, transducers, battery and wireless links into these tiny earpieces that fit right in the ear. The most complicated part of the design was enabling the left and right earphones to communicate via Bluetooth with the smartphone in full synchronisation. This is the definition of the term true wireless stereo. This technique is now fully developed.
So how do you develop and improve wireless in-ear headphones? Sony is now into the third generation of its top-of-the-range "1000" series. On paper, the XM4 is a similar offering to the XM3. However, Sony has managed to further miniaturise its earbuds making them more comfortable. The XM3s protruded from the ear, while these new WF-1000XM4 sit completely in the ear for an exemplary fit. As regards the sound, the transducers have gained 20% more surface area to improve the reproduction of the entire frequency range to further enhance the sound quality without sacrificing the practical side.
● Price: €279.99
● Connectivity: Bluetooth
● Codecs: SBC, AAC, LDAC
● Frequency response: 20 Hz - 40 kHz
● Transducer: 6 mm diaphragm
● Features: touch controls, microphones for hands-free telephone and voice assistants, active noise cancellation, mobile application with graphic equalizer, Qi wireless charging
● Accessories: three pairs of earbud tips, carrying and charging case, USB-C cable to USB-A
● Weight: 41 g
Overview of the WF-1000XM4
When we talk about Bluetooth in-ear headphones, there are many different formats. Apart from the fact that each manufacturer has its own design, the way in which the earpiece is held in the ear can be quite different. And more or less comfortable. The previous XM3s were massive and protruded well out of the ear. The new XM4 in the shape of a small ball fits rather well inside the ear. With a weight of a mere 41 grams, they can be easily forgotten.
Of course there is the protruding part that goes into the ear canal. It ends in the horn where the sound comes from. This end is covered by a foam tip. Sony provides three with the XM4; small (S), medium (M) and large (L). They are identified by an internal coloured ring and are available as accessories. So you can change these tips when they are worn out. The combination of the tips and the shape of the earbud provide a reassuring hold in the ear. There is little chance of them falling out by themselves.
This does not necessarily make it any easier to insert the earbuds. To avoid getting it wrong, place the box in front of you, pick up an earbud and bring it up to your ear without turning your hand. This way the earbud will find its natural position in the ear. Finally, you push very lightly on the small metal part. The earbuds fit so firmly in place that it is not so easy to remove them because, depending on the shape of your ears, there is not much surface area to grip. It's an acquired knack, but we prefer this light, natural format to the overly cumbersome previous version.
These earbuds have a new 6mm diaphragm. Despite the more compact size, Sony has successfully integrated a larger speaker into the WF-1000XM4. So it is one single transducer which handles reproducing all the frequencies. Compatible with Hi-Res playback using the Bluetooth LDAC codec, the XM4 is capable of reaching 40 kHz.
Using the WF-1000XM4
The XM4 comes with its classic re-charging box. Very small when compared with the XM3, it benefits from the miniscule size of the earbuds. Note that the XM4 is available in black or a silvery white, with its box in the matching colour. The earbuds are magnetised for perfect positioning to be recharged by their box. The battery life is 8 hours, and the box can recharge them twice for a total life of 24 hours. The box itself can be charged either through its USB-C port, or wirelessly on a standard Qi induction charger.
High-end earbuds like these Sony ones have active noise cancellation for ambient sounds. The Japanese manufacturer excels in this area effectively cutting out annoying sounds such as crowds in the street or the in-flight rumble of jet engines. You are never totally isolated so you don't lose touch with the world around you. What is more, you can at any moment switch to transparency mode by leaving your finger pressed on the left earbud, its default setting. The XM4 is also capable of continuously analysing ambient sound through its microphones to apply the most appropriate level of reduction. This is confirmed by playing a tone whenever a new environment is detected. The application also helps you find the right size tip for your ears, which contributes to the natural isolation.
All the settings can be configured from the Sony Headphones application. This opens to first show the battery level of each earbud and of the box. As for the sound settings, a five-band equalizer allows you to customise the sound. Added to this is a setting called Clear Bass and its purpose is to reinforce the lowest frequencies. The DSEE Extreme mode, used on many Sony products, takes care of upscaling the playback of even the most compressed tracks by using artificial intelligence to recognise musical genres and different instrumentation.
The two microphones built into the XM4 are used for ambient noise analysis as well as for hands free telephoning and voice exchange with Google's Assistant and Amazon's Alexa. Voice recognition is enhanced by bone conduction capture when speaking. Simply ask them to turn down the volume or move on to the next track. Because the controls on the earbuds are kept to a minimum, one press on one side changes the level of noise cancellation and one press on the other earpiece pauses or restarts playback. However, it is possible to reassign either of these with a volume control: a short press to increase it, a long press to lower it. All of these functions are contained in the mobile app.
The WF-1000XM4 has other qualities such as water and sweat resistance for use in your sports sessions. Bluetooth latency is reduced to a minimum for an ideal synchronisation with videos and to avoid lags between sound and image. As soon as one earbud is removed, the music pauses. Once both earbuds are removed, they automatically go into standby mode to conserve battery life. It is difficult to ask for much more of these headphones, as they are already so feature packed.
Once we were connected to a Sony Android smartphone, we launched our favourite Qobuz playlists on the WF-1000XM4 from the native app. We can tell you that we were not disappointed. We listened using neutral equalization, without any adjustment. Neutrality is exactly what these Sony earbuds offer. Everything seems to be in its place, with no major emphasis on any one register, with the possible exception of the higher bass notes, which produce a singular impact that is rarely found in the field of consumer earphones, especially Bluetooth earphones. We suspect that there is a certain amount of emphasis in this range designed to meet the expectations of today's users. This bias is perfectly suited to listening to the latest Kool & The Gang album and more particularly to the track Good Time. The drums' beat and the bass notes are clearly audible in the energetic accompaniment. There is no risk of falling asleep listening to the XM4.
We moved on to a softer listening experience through the voice and piano duo Melody Gardot and André Manoukian on their album of Gainsbourg covers. Their intimate ambience is authentically reproduced with an interesting breadth of sound that goes way beyond the width of these earbuds. However, the voice is still extremely well centred, so we are talking here about the limitations of such earbuds and of their technical equipment. However, their positions are still discernible between the lowest notes on the left and the high notes on the right. The musical ensemble is tighter, more compact in comparison with a classic over-ear headset.
Total change of mood with the album Loving In Stereo by the English band Jungle. The superbly crafted numbers, which opened up to reveal a great deal of separation between the instruments, the sounds and the multiple effects, turn the spotlight on the analytical capabilities of the WF-1000XM4. The earbuds are soon forgotten, with their palpable sense of width and depth, so that we are immersed in the very heart of the music. This total immersion experience is also reached when listening to classical music, such as Brahms' Symphony No. 2 in D major conducted by Herbert Blomstedt. Even some large over-ear headphones do not offer as much openness nor such a wide spread of the orchestra, whilst maintaining realistic placements of the different sections. Even if extreme precision is unattainable for the XM4, the overall result is amazing for such small earbuds.
Breadth of the soundstage
Low frequency boost
Effective noise cancelling
Functions in the app
In-ear format that may not suit all ears
With the WF-1000XM4, Sony demonstrates its expertise in the field of in-ear headphones. Being true wireless Bluetooth, they make life easier by fitting into the ears and then being forgotten. The new format is ideal in terms of comfort, although the XM4 may not fit all ears. If these earbuds suit you, then you'll be getting the very best in terms of today's available features and sound quality. The XM4 is capable of transporting you to the centre of a wide soundstage in a simple and natural way, without artifice. If you want to customise the sound, you can boost a particular register according to your taste; the five-band equalizer allows you to do this. The active ambient noise cancelling is sufficiently effective to create a near silent environment. Listening to your music is all the more enjoyable because it is no longer necessary to turn up the volume so loud. Whether on the move, playing sports, on the street or simply at home, the WF-1000XM4 is the perfect companion, a complete success in every situation.