Sound Science in the Digital Age: Understanding Huawei's Largest Audio Laboratory from the Father of Mathematics

As the time comes to 2022, questions about the wearing stability and necessity of true wireless earphones TWS are no longer a problem. Instead, more subjective concerns such as "good or bad sound quality" and "I don't know which one to choose" have become the focus of acoustic manufacturers and mobile terminal manufacturers.

The perception and preference of sound are very individual, which makes people have different opinions on the value of TWS headphones. It is easy to fall into metaphysics such as "Sony is better" and "hydropower sounds better than thermal power". Personal preferences do not need to be defined scientifically, but the development of the TWS headset category requires consensus and standards, which cannot be separated from quantitative and qualitative scientific methods.

(Pythagoras, ancient Greek mathematician)

For Pythagoras, the pleasure of sound was defined by science. British author Mike Goldsmith wrote in the book "Oxford General Course: Sound": Acoustics is one of the earliest fields of scientific research. As early as around 500 BC, Pythagoras heard the sound made by blacksmiths when they struck hammers. He weighed the weight of the hammers used by the blacksmiths and found that the weights of the hammers that made pleasant sounds were simply multiples, and the octave was the most harmonious of all intervals. TWS headphones must provide consumers with a better experience and meet all-round needs such as noise reduction, sound quality, and interaction, which cannot be separated from rigorous and precise scientific support.

Recently, on August 18, Huawei's largest laboratory in the audio field to date, the Shanghai Audio Laboratory, was opened to the media for the first time, elaborating on Huawei's full-link solution for audio from hardware, software to wireless high-definition transmission. It turns out that a Huawei TWS headset has to go through a series of tests from birth to delivery.

Along this technological journey of TWS headphones, it is very suitable to dig deep into Huawei's technological "background" in the field of digital audio, and also take this opportunity to examine what kind of systematic capabilities TWS headphones actually need.

First stop on the journey: the origin of science

As mentioned before, science is the best yardstick for human understanding and perception of sound. About 400 million years ago, when amphibians settled on land, the eardrum and cochlea began to evolve in order to detect sound transmitted through the air. The appearance of sound even predates vision. This is the origin of science.

The ancient Greeks exhausted their imagination in architectural structures. The Epidaurus Theater in the 4th century BC used limestone to make seats to absorb sounds with frequencies below 500 Hz and reduce the noise of the audience whispering. In the First World War, people realized that high-frequency sounds could be used as part of the sonar system, and they became interested in them. During the Second Industrial Revolution, Edison invented the phonograph, which allowed recorded music to be shared with audiophiles through electroacoustic conversion equipment, driving the art of sound. In 1979, Sony's first tape Walkman TPS-L2 was unveiled, and portable headphones entered the market. In 2016, AirPods came out, achieving binaural separation, and also opened up the competition for TWS headphones.

It is not difficult to find that the development of headphones is directly related to the progress of human technology, the endless pursuit of sound quality, and the increasing popularity of the demand for enjoying music. It has evolved along two core lines:

One is portability. On the one hand, the size of headphones is getting smaller and smaller. The headphones that were born in 1891 were designed for communication. When using them, they needed to be supported on the shoulders with a weight of several pounds. With the popularity of devices such as Walkman, iPod, and mobile phones, headphones have become the mainstream equipment for enjoying music with their compact size and more friendly price compared to speakers. The production process has also made the size of headphones smaller and smaller, and in-ear earplugs can pour sound into the ear canal. The other side of portability is reflected in the evolution from wired to wireless, which reduces the constraints of connecting wires. In the last century, wireless stereo headphones using infrared as transmission were born, but the distance and range of infrared emission were limited, and the transmitter and receiver devices could not be miniaturized, so they could not be widely popularized. There have also been wireless headphones with WiFi, but the cost of WiFi construction is high, which cannot meet the user's mobile needs to enjoy music at any time. At the same time, pairing is complicated, and changing WiFi requires re-entering the password, which is very cumbersome. The reason why TWS headphones have become the mainstream solution for wireless headphones is due to the superiority of Bluetooth in bandwidth, power consumption, connection stability, etc., coupled with the popularity of smartphones and the wireless trend, TWS headphones have become the preferred solution to meet the public's auditory experience.

The second is sound quality. Acoustic brands were the first to invest in the field of headphone manufacturing. In 1959, Japan's STAX company launched the world-shaking SR-1, which had unparalleled delicacy and low distortion performance, leaving the dynamic headphones of the same era behind by several positions. In 1979, Sony entered the headphone industry, and the "Sony Method" attracted music enthusiasts around the world with its sound quality. TWS headphones use wireless transmission, getting rid of the constraints of headphone cables, and the technical difficulty in the auditory experience has also increased.

On the one hand, good sound quality requires the integration of high-quality acoustic units, which poses a high challenge to the design and craftsmanship of TWS headphones. For example, the Audio-Technica ATH-CKR7TW, which uses sound quality as its selling point, uses a DLC-like diamond carbon coated diaphragm unit, which achieved very high unit quality at the time, but also resulted in the product being too large and not comfortable to wear.

In addition, TWS earphones have removed the connection wire. Although the feature of separating the left and right ears is convenient, new problems such as low connection stability, distinguishing between the main and auxiliary ears, and large delay have emerged. They often need to be optimized in coordination with mobile phones and other devices. However, many TWS earphone manufacturers do not have product lines such as smartphones and wearable devices. They are slightly inferior to multi-category manufacturers such as Huawei and Samsung in terms of seamless coordination, reduced delay, and synchronization stability. For example, Samsung Galaxy Buds can be seamlessly connected with Samsung mobile phones, and Huawei Freebuds Pro2 works with Huawei mobile phones. It supports high-end Bluetooth audio transmission standards HWA and Hi-Res Audio Wireless dual gold label certification, plus the earphones come with four magnets 13mm high-quality dynamic units, the sound quality is naturally better. The advantage of traditional acoustic manufacturers is long-term content accumulation. For example, Sony provides a monthly subscription service of "Sony Select", where users can enjoy Hi-Res sound sources that surpass CDs.

At the same time, TWS headphones are close to the ear canal. If the noise reduction and control are not good enough, users will turn up the volume to hear more clearly, which will damage hearing over time. In the digital age where "software defines everything", active noise reduction, high and low frequency adjustment, etc. to control the dynamic performance of sound require the development capabilities of combining software and hardware, and traditional acoustic manufacturers may not be able to do it with ease. For example, Sony WF-1000X, as the first TWS headset with active noise reduction function, did not achieve the noise reduction effect that many people expected.

Looking at the changes in headphone products, we can find that the advancement of acoustic technology, the development of digital audio, the lowering of the threshold for enjoying good sound quality, and so on, multiple factors jointly determine the attractiveness of headphones to consumers. In the future, the competition around TWS headphones will be even more intense, which also shows that innovation has begun to enter the deep water zone. It is mainly manifested in: shallow innovation begins to "roll inward", such as being limited by the breakthrough cycle of new technologies and new materials, and the volume can no longer be reduced, and homogeneous competition begins in appearance and equipment. TWS headphones that cost dozens of yuan are beginning to be stuffed into dynamic units. There are not enough new technology highlights, and at the same time, supply chain innovations such as "technology based on shell replacement" have emerged. And some unresolved experience pain points require deep innovation to overcome, such as latency, sound quality, noise reduction, etc., so that the sound can be changed from "audible" to "good to listen to", which cannot be solved by isolated technology, and requires comprehensive efforts in coding and decoding technology, sound source, hardware, and algorithms.

From this perspective, the emergence of Huawei's Shanghai Audio Laboratory is timely. Let us follow the scientific roadmap to see what hard-core technologies are needed to support the upgrade of TWS headphones.

Second stop of the journey: Huawei earphones testing ground

The rigorous testing in the laboratory may seem a bit nitpicking for a pair of headphones, but it is something that consumers love to see. As Huawei's largest audio laboratory to date, Huawei's Shanghai Audio Laboratory may be a "testing ground" for a TWS headset, creating the ultimate audio experience through layers of testing and trials.