After AirPods, future headphones may be “invisible”

In Jin Yong's novel "The Eight Parts of the Dragon", Duan Yanqing used internal force to transmit the sound to Xuzhu's ears to help him break the game of Zhenlong, but the people around him did not notice it. This martial arts is called "transmitting sound into secret." .

▲ Picture from: "Dragon Babu"

The famous science fiction writer Arthur Clark once said that any sufficiently advanced technology is no different from magic. Nowadays, the miracle of "transmitting sound into secret" can also be achieved through technology.

Recently, a technology company in Israel, Noveto, released a new product that can transmit audio to specific users over the air, while others can’t hear it, just like wearing an invisible AirPods.

Imagine that when you play music while watching a show on the subway, you can turn the volume to the maximum while watching a football late at night, without disturbing others, and you can hear clearly, then the headphones seem to be useless.

Yes, the ultimate goal of this technology is to replace headphones . After making the headset move from wired to wireless, it directly enters the "invisible" stage.

What kind of black technology is this? Is it really that amazing?

What is it to transmit music without headphones?

The device released by Noveto is called SoundBeamer 1.0 . Its appearance is no different from an ordinary speaker. The reason why audio can be directionally transmitted without earphones is based on a new audio technology "sound beaming".

The so-called "sound beam" can be regarded as directional emission of sound as the light of a flashlight. SoundBeamer 1.0 locates and tracks the position of the user's ears through the built-in 3D sensing module, forming a "sound pocket" around the ears, and transmits audio information through ultrasound.

Therefore, the user can hear 360-degree surround sound even without wearing headphones, while the user next to it cannot. When the user's head moves, the sound can also automatically "follow", but the effective range of this follow is not disclosed by Novto.

This technology is very reminiscent of the updated spatial audio function on iOS 14. Apple’s function is actually to simulate surround sound effects on AirPods Pro through directional audio filtering, and rely on the gyroscope to sense the movement of the head, track and synchronize each in real time. The direction of the sound field.

The difference is that "spatial audio" needs to rely on wearable devices like AirPods Pro, while SoundBeamer is farther away from users. Although both have built-in digital signal processing and chipsets, the latter tracks and adjusts the sound signal. The difficulty is obviously higher.

At present, Novelo does not have a detailed introduction to the internal structure and core technology of this device, but it demonstrates some functions of SoundBeamer online.

In one of the demo scenes, a staff member used SoundBeamer to transmit audio while playing a gunfight game, while colleagues on the other side could not hear the sound of the game.

In fact, as early as 2018, Noveto had shown a similar prototype product to the media. According to a CNBC reporter who had experienced this product at the time, when ordinary audio was switched to Noveto's technology, it was like having a private theater.

Noveto's speakers tracked my head movement through the camera, transmitting the sound to my ears. When I was talking to Wallace next to me, I could hear the audio from the speakers, but Wallace couldn't.

SoundBeamer 1.0 is the first product officially released by Noveto. Noveto CEO Christophe Ramstein believes that SoundBeamer's innovation in audio product experience can be compared to iPod .

It is reported that this product will be on the market before Christmas next year, when the volume of the device will be smaller than it is now. According to Novelo's vision. In the future, in addition to launching such free-brand products for directional transmission of audio, the technology will also be licensed to third-party hardware to allow more devices to support this technology.

It seems to be able to shout "Amazing" to this product, but since this product has not yet been officially launched, there is only a demo, which inevitably makes people question it. After all, in the audio and headset market, it seems that it has not appeared before. Mature consumer products using this technology .

However, it is impossible to conclude that this is another PPT product, because the technology behind this has actually been developed for decades, and many products have also been commercialized in some industries.

The technology behind the black technology may be much older than you

The "sound beaming" technology developed by Noveto is a kind of audio directional transmission technology, also known as "directional sound technology". Simply put, it allows the sound that originally diverged in the air to propagate in a fixed direction.

At present, the directional sound technology is mainly realized in three ways, namely, the concentrating cover technology, the speaker array technology and the directional transmission based on ultrasonic sound frequency, while the third method used by Noveto.

However, there is a problem. The human ear can hear the sound frequency of 20Hz – 20KHz, and it is impossible to hear the ultrasonic wave. So how can the ultrasonic wave transmit the audio signal and let the target user hear it?

A concept called " nonlinear propagation " needs to be cited here, but if you want to clarify this technology, you may need a paper. You just need to know that when the ultrasonic signal is emitted into the air, it will have a certain effect to produce a new frequency.

Therefore, it is enough to make this new frequency fall within the audible range of the human ear. Compared with the sound frequency that we can usually hear, the ultrasonic signal is easier to modulate the direction. These characteristics also make the ultrasonic wave become the directional sound technology. An ideal carrier.

And in order to further enhance the effect of sound directional propagation, countless ultrasonic monomers are used to cancel out the sound in the direction where the sound is not needed, and the waveform is superimposed in a specific direction to enhance the sound signal, which is somewhat similar to the working principle of active noise reduction headphones.

▲ Based on directional sound technology, different audios can be played in a living room without interfering with each other.

The self-demodulation effect of the nonlinear propagation of ultrasonic waves in the air was discovered by researchers as early as the 1960s. In the 1980s, some people had begun to develop speaker equipment based on this directional sound technology.

As for the other two directional sound technology solutions, the sound-collecting cover technology needs to be experienced in a hemispherical cover, while the speaker array technology requires a large number of high-frequency speakers. Both the transmission effect and the reliability are not as good as the ultrasonic-based directional sound technology.

This technology also fills a big gap in the acoustics field and is regarded as an important technological change by many insiders . From this perspective, Noveto dared to compare the innovation of its own products with the iPod, at least with some theoretical support.

The US destroyer, the aunt of the square dance, all used this technology

However, this technology is entering the public's field of vision until the 21st century, and among those who promote the mature commercial use of this technology, Joseph Pompei has to be mentioned.

As early as 1998, the MIT Media Lab of the Massachusetts Institute of Technology initiated the research on directional sound technology, and gave this technology an image of the name-Audio Spotlight (sound spotlight), and announced the successful development in 2010.

So in 2012 MIT Media Lab began to cooperate with a company called holosonics to commercialize this technology. Joseph Pompei is the founder of this company, and he is also one of the main developers of "Sound Spotlight".

It is worth mentioning that Joseph Pompei is a rare genius in the field of acoustics. At only 16 years old, he became the youngest acoustic engineer in the history of Bose, the largest sound effects manufacturer in the United States.

In 2018, the number of users of "Sound Spotlight" technology exceeded 1 million, of which museums and other exhibition halls accounted for a large part. These venues can transmit different introduction audio to different exhibition areas without interfering with each other.

The supermarket is also the target user of "Sound Spotlight", which is mainly used to broadcast various discount information in different regions. When you walked in the mall, a strong male voice suddenly came in your ear: "OMG, buy it!" I wonder if you can accept it?

In addition, this technology is expected to be used to solve the problem of square dance disturbing the people. In the past few years, residents in a community in Zhejiang could not bear the sound of the square dance aunt’s tweeter. They raised 260,000 yuan to buy a "remote directional strong sound reinforcement system". Playing with the square dance aunt .

This method of "suppressing noise with noise" is not desirable, but if the square dancer can use speakers based on directional sound technology to play music and concentrate the music in a fixed area, the harassment to surrounding residents can be greatly reduced.

At present, some domestic startups are developing similar products. For example, the "Qing Hear Acoustics", which completed tens of millions of yuan in A+ round of financing this year , launched a smart square dance system based on directional sound technology in 2017 , and launched a pilot in Suzhou application.

▲The directional speaker of the smart square dance system.

In addition, directional sound technology can also be used as a weapon in the military field, that is, directional sound wave weapons. The National Guard of the United States used LRAD directional sound wave dispersers to drive away crowds, and the Navy also used this equipment to expel and warn target ships.

In the sci-fi movie "Invincible Hulk", the US military used a more powerful directional sonic weapon to deal with the Hulk, which was once shocked to the Hulk.

It can be seen that the current commercial field of directional sound technology is concentrated in large-scale speaker equipment on the industry side. There are very few products for ordinary consumers. Among them, price and portability are not small obstacles. In addition, the user needs of C-end and B-end are also very high. very different

Replace headphones? Not impossible, but not easy

In the field of directional sound technology, the miniaturization of equipment has been a major research direction at home and abroad. The miniaturization of equipment is an indispensable step towards consumer products. After all, if you have to hold a big speaker to achieve directional audio, why not wear a headset?

Although the portability of the device shown by Noveto is not as good as that of a mobile phone, it is already much smaller than the previous product.

In addition, Samsung also released a concept product SRay called "the world's smallest directional audio" at CES 2018. The price is about 209 US dollars. Although it has not been officially launched on the market, this is probably the ideal form for comparing directional sound technology consumer products. .

Manufacturers who have basically developed similar products have more or less mentioned an ambitious goal: to eventually replace "headphones . " But obviously it is not that easy, and this goal is still far away.

In addition to volume and price, the sound quality of directional speakers is not a bit worse than traditional audio equipment. Among them, bass is the biggest shortcoming, which is also the price that must be paid for directional sound transmission.

This is not a big problem in museums, supermarkets, military and other fields, but in entertainment scenes such as film and television, music, and games, users have much higher requirements for sound quality. In 2016, home directional sound products were also launched, but consumers did not Pay the bill.

If directional sound technology really wants to produce a product that can replace headphones, in addition to being maturely applied to portable small devices, it must also ensure the sound quality experience. At the same time, the price cannot be too high. There are still too many technical problems. solve.

But this does not prevent us from imagining the application of this technology in the future. In addition to the possibility of replacing headphones, a new interactive interface may also be born .

Apple has applied for a listing called "it portable media devices designed for directional audio technology patents", the devices form a "voice interface" in directional audio sent around the user, so that non-visual interaction, like a voice-based multi touch.

As we mentioned in a previous article , AirPods revolutionized headset interaction, making the interaction between people and devices closer to the "pervasive computing" conceived by Mark Weiser.

Pervasive computing aims to create a computing environment that is "ubiquitous, ubiquitous, and invisible" in which users interact with devices in a natural situation that they are not aware of.

If wearing AirPods has made people "insensible" in many scenes, then is "invisible" directional sound technology more in line with the vision of pervasive computing?

Whether this day will really come, we may wait and see.

The title picture comes from: News BBT

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