Interview with Sony WH-1000XM4 Engineers

Sony Japan has put up an interview with some of the engineering team responsible for the WH-1000XM4. The interview is in Japanese, but Google translate does a decent job at translating it.

You can check out the interview here. I will admit this interview is also a bit like an advertisement for the new headphones, but it does provide some insight into the development.

New Bluetooth chip and NC working together

Previously in the WH-1000XM3, the QN1 was the main chip responsible for the noise cancellation, but this time around the QN1 works together with the new Bluetooth chip, sensing the noise and music and adjusting the level/degree of noise cancellation up to 700 times/second. An algorithm is used to combine the QN1 and BT chip information which leads to improved noise cancellation. Since this is an algorithm, perhaps future firmware updates could further improve noise cancellation performance.

On a side note, while in previous posts I claimed we would be looking at the Mediatek MT2811S in the new WH-1000XM4, this may not be the case. The Bluetooth certification showed AB15abx/MT28abx, so it could be either a Mediatek or Airoha chip. In the FCC teardown photo below, the chip appears more matte than shinny as seen with the MT2811S. Of course the photo is of poor quality, so I cannot make any final judgments here.

In a 52Audio teardown of the WF-XB700, the Bluetooth chip turned out to be an Airoha AB1552, rather than the Mediatek MT2811S. But I will note the WF-XB700 has its own listing in the Bluetooth certification, where as the WH-1000XM4 is grouped with the WI-1000XM2 which is confirmed to be using the MT2811S. We will have to wait for a first teardown to confirm the Bluetooth chip.

DSEE Extreme

Sony describes DSEE Extreme is a further evolution of DSEE HX, which uses AI technology to “reproduce with high accuracy the frequency responses of the original sound source lost during compression”. In the interview, the engineers state, that deep neural network technology is used to enhance/upscale the vocals. Normally a deep neural network would require a connection to the cloud, but this is not possible with the WH-1000X4, so it seems an algorithm is used from my understanding. I am guessing this algorithm was developed using AI and then transferred onto the headphones. With DSEE Extreme being an algorithm, perhaps future firmware updates could be used to adjust it or improve its capabilities.

Personally I never turn on the various enhancements on my Walkman, but when I did, I never heard any major difference. The battery life also takes a major hit when using DSEE, so this was another reason I stayed away from DSEE myself. For anyone with the new WH-1000XM4, does turning on DSEE Extreme change/improve the sound quality much? Post below in the comments.

Speak to Chat

The interview provides some details about how it works but the interesting aspect is that it also uses deep neural network AI technology like DSEE Extreme. It uses a special “conversation detection algorithm”. The engineers mention that the AI tech for speak to chat will slowly become smarter by learning from the user. Not sure how, perhaps it transfers data to the phone and then via the Sony Headphone app sends it off to some server for algorithm improvements? Personally, I do not expect that, but who knows. Speak to chat uses the feed-forward microphones, and the multi-array of microphones at the bottom.

It seems like the amount of microphones has not changed from this photo, 3 on the bottom of the left cup, the same as in the WH-1000XM3. So it will be interesting to see a teardown and compare the internal components and see the changes, especially to see if there are any additional microphones that were mentioned in the Walmart leak.

Built-in proximity sensor and accelerometer

One major addition to the new WH-1000XM4 is the proximity sensor which can be seen inside the left ear cusp. But in addition to this, there is an accelerometer built into the headphones which also detects the movement of taking on and off the headphones. To prevent accidental operation, the touch panel on the right is disabled as well when taking off the headphones, simple yet clever.

1 gram lighter than their predecessor

The WH-1000XM4 weight in at 254 grams versus 255 grams in the WH-1000XM3, an entire 1 gram lighter. This may not sound like much, but there have been various changes to the structure to strengthen various parts, the addition of the proximity sensor and slightly different materials. Some of the weight saving has taken place in the earpads, which are now slightly lighter than before. Will be interesting to see if the battery size has been reduced to lower the weight. Anyone willing to disassemble their newly acquired WH-1000XM4?

That is most of the interesting stuff I could gather, if anyone finds any more WH-1000XM4 interviews on other websites, please link them at the bottom in the comments.