Lack of appeal.
For AirPods 3, many old AirPods users around me have given such comments. But as one of the benchmark products in the field of true wireless headphones, it still has a strong influence, Tianfeng International analyst Guo Mingxi gave an estimated sales volume of AirPods in the fourth quarter of 2021 in a recent report: 27 million units.
A number that is shocking enough.
This is obviously inseparable from the promotion of the new AirPods 3, in a whole product line, Apple has accurately designed a position for AirPods 3, stronger than the previous generation, fresher appearance, and lack of a killer function than AirPods Pro - noise reduction.
Even if it is a gradual innovation, it is not easy to meet the evaluation of benchmark products, and recently foreign media What HiFi interviewed Gary Geaves, vice president of acoustics at Apple, to reveal the design story behind AirPods 3.
Let everyone "listen" the same
Wearing comfort, has always been a keyword of the AirPods experience, Apple is also very important, from the initial EarPods wired headphones have investigated hundreds of people, collect ear canal, pinna and other information, trying to make the headphones more suitable at the same time, have a better sense of wearing comfort.
This experience feature is well inherited into the AirPods 3, the semi-in-ear structure is less foreign to wear, but also can be very good to clamp the pinna, we also mentioned in the review that after many exercises, we also failed to throw the headphones off.
The wearing experience can be continuously optimized by investigation and research to move towards consistent comfort, but what about sound quality?
Everyone's auricular structure is not exactly the same, which means that different people may hear different sounds, "especially bass," gary Geaves emphasized.
For a product family like AirPods with hundreds of millions of ownership, consistency of experience is important. The extremely small size of the AirPods 3 adds to the difficulty of this matter, and the battery, chip motherboard, etc. all occupy a lot of space.
The final solution given by the Gary Geaves team is "adaptive equalization," which is to add an inward microphone inside the headset to monitor the music played by the speakers in real time. Once it is detected that the playback content has changed due to the structure of the ear and the way it is worn, the headphones will make adjustments to the music.
This allows the bass to play correctly and avoid the effects of each person's different ear structures, providing a consistent music playback experience.
Another feature of airPods 3 is spatial audio, which gives music a certain degree of spatiality, and no matter how your head turns, the sound you hear will feel like it's coming from an iPhone.
Like regular music playback, spatial audio is also affected by the structure of the human body, says Gary Geaves:
The shape of the ears, the width of the head, and to some extent, the location of the facial features, and even the shape of the head, mean that everyone hears a different voice.
Gary Geaves' team surveyed thousands of people in an attempt to create a model of the perceptual response that was closest to everyone. Making spatial audio sound natural and realistic is challenging and requires a lot of consideration.
For example, the location of the virtual speaker, how far it is from the wearer, the angle of the speaker, etc., whether the virtual space is a simulated church or a personal room, the difference between the two lies in the size of the space and the internal furnishings, the former is obviously larger and more empty, and the latter is piled up with a large number of personal belongings, which often leads to smaller space.
These will affect the embodiment of the spatial sense of sound, and spatial audio is not simply sound attenuation or delay playback.
Geaves gives a very intuitive example of a virtual speaker that is farther away from you when watching a movie on an Apple TV than when watching on an iPhone. Obviously, this is more in line with our daily movie-watching habits, mobile phones are closer, TV is farther away.
Behind the spatial audio, the new customized amplifier has played a big role, so that AirPods 3 has a high dynamic range and extremely low latency, with the powerful computing power of the H1 chip, constantly identifying and adjusting music, so that everyone can get an almost consistent sense of hearing.
AirPods 3 disassembly. Image source: iFixit
It's not easy to do this in lightweight wireless headphones, and with Geaves there are no off-the-shelf components, airPods 3 is basically built from scratch using custom components, including very low distortion speakers, bass ports, new custom amplifiers and other components.
Calculates the target for the audio
When the original AirPods were released, the features of light body, comfortable wearing, and low latency won its recognition, from group ridicule to pursuit, and now AirPods are moving towards computing audio, which Apple uses to build better experiences and technical barriers.
The adaptive equalization, spatial audio functions just mentioned have calculated audio behind them, the inward-looking microphone inside airPods 3 is like a sensor constantly collecting playback data, and the H1 chip is like a brain, processing data and making feedback, and finally adjusting the headphones to output the correct sound.
HRTF
When it comes to spatial audio, Geaves mentions a data concept HRTF (Head-Dependent Transfer Function), which is a concept used to describe the transmission of sound to both ears, which digitizes the effects of the human head, ear canal and trunk on sound propagation, and the HRTF parameters are different for different people.
It was based on a survey of thousands of HRTFs that the Geaves team was able to derive a relatively universal HRTF model, supplemented by H1 chips and software algorithms, to determine the environment and location, and finally make the music have a sense of space.
The AirPods Max, the highest positioning in the entire product line, uses 18 sensors to collect data, spatial audio, adaptive equalization, noise reduction functions, these features are supported by H1 chips, a song played from AirPods needs to go through a series of processes such as data acquisition, chip processing, algorithm feedback, etc. The music you hear is "calculated" processed.
So, who decides what the "right" music looks like?
In the interview, Geaves mentioned the team's goal: we respect the music and the emotional impact it can have, and we want to provide this natural experience.
As a sound medium with specific rules, music can drive emotions, trigger memories, create one special picture after another in your and my brains, and the emotional experience brought by different melodic expressions is different, which is related to the unique expression of singers and creators.
The vast amount of data provides data for the acoustic team led by Geaves to turn the music into digital, the engineers, the mixers work together to adjust, and the team will also establish contact with the music creators to ensure that the music, after various calculations, still conforms to the author's musical expression.
Computational Audio attempts to digitize music, presenting it in a variety of data, but its ultimate goal is still to conform to the original appearance of the music and the authors' musical expressions.
What's next for AirPods?
Where AirPods will go in the future, including well-known analyst Mingxi Guo, many predictors who have successfully predicted Apple products have proposed two directions, non-destructive music and health monitoring.
From the current situation, the health function is still far away, although Apple said that the skin sensor in AirPods 3 can detect human skin, but so far its main role is to ensure that the ear detection is normal operation, so that the headphones can recognize the ear, remove the stop playing, and automatically play music after wearing.
Apple Music has added lossless music support in 2021, and according to the 9To5Mac, Apple seems to have reached the goal of 90 million lossless music libraries.
At present, including AirPods Max, the entire AirPods product line can not directly experience the lossless music in Apple Music, compared to ordinary music, CD-level lossless music records more information, resulting in larger data, more data transmitted at the same time, Bluetooth bandwidth can not load such a high amount of data.
Bluetooth technology is mainly to ensure short-distance communication, small and medium-sized data transmission technology, versatility and low power consumption is one of its main characteristics, which is also one of the reasons why AirPods 3 can ensure 6 hours of music playback time.
To this end, the Bluetooth Technology Alliance (SIG) has specially developed a number of specifications, among which the A2DP specification responsible for Bluetooth audio transmission requires Bluetooth transmission power to be within 768 kbps, while the general CD-level lossless music requires a transmission rate of about 1400kbps, and the gap between the two is huge.
High transmission rate often means high power consumption, even if there are Bluetooth headphones to support 1400kbps lossless music transmission, but the battery life is only more than 1 hour, I am afraid that not many consumers are willing to buy it.
Since the specification can not be surpassed, then from the transmission to start, in fact, the A2DP specification supports a variety of Bluetooth encoding methods, the most common SBC, as a traditional encoding method, its sound quality performance is general, but fortunately the versatility is extremely high, most bluetooth devices are supported.
For example, in the Bluetooth 5.2 protocol, bluetooth technology alliance added a Bluetooth encoding format called LC3, which improves sound quality and also ensures small capacity, LC3 achieves the same sound quality as SBC Bluetooth encoding, and the transmission rate requirements are only half of SBC.
Wondering if you're a gold ear? Click here to try out the LC3 encoding and SBC encoding music comparison. Image courtesy of Bluetooth Technology Alliance
Qualcomm launched the aptx Bluetooth encoding protocol development has now become a large family, aptX HD, aptX-adaptive and other different specifications of the version, the former the highest transmission rate of 576kbps. Recently, Qualcomm also launched a lossless aptx lossless technology, claiming that it can reach the CD level of music experience, but the relevant details are still to be announced.
aptx lossless . Image courtesy of Qualcomm
Apple's AAC format, with a maximum transmission rate of 256kbps, still has a lot of room to rise, and power consumption and sound quality still need to find a point of balance with each other.
At the end of the interview, Geaves also said that the Bluetooth transmission bandwidth limits the play of AirPods, and spatial audio also has more music information, which apple acoustics team can only carefully adjust within the specification to ensure that spatial audio can run normally.
As for whether Apple will create a new Bluetooth encoding method like Qualcomm in the future, bypassing the restrictions of Bluetooth transmission, Geaves did not explicitly answer, perhaps this will have to wait until the next generation of AirPods is released, the answer can not be announced.
Caption from: tomsguide
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