“The world is constantly changing. This state of continuous development means that the way we interact with the world, equipment, and others is also changing. In addition to profit, there are two important forces that dominate this change: one is the development of technology, which promotes our continuous innovation and brings a variety of devices and applications that we are accustomed to today; , It is driven by the new crown epidemic that people are more concerned about their health.
“
Author: Jon Gabay
introduction
The world is constantly changing. This state of continuous development means that the way we interact with the world, equipment, and others is also changing. In addition to profit, there are two important forces that dominate this change: one is the development of technology, which promotes our continuous innovation and brings a variety of devices and applications that we are accustomed to today; , It is driven by the new crown epidemic that people are more concerned about their health.
When people have more time for entertainment, immersive technology ushered in development opportunities. Consumers can now purchase virtual reality and augmented reality headsets from many manufacturers, and amateur developers and professionals can also use development tools to render virtual worlds and scenes. These display technologies are hitting media headlines from time to time, and at the same time the corresponding audio technology has not been left behind.
Among the five recognized perceptions, sound may be the first that people feel. Whether it is the abundance of nature, the richness of orchestral music, or the agitation of spiritual songs, sound, like any other perception, will have a profound impact on our emotions and physiology.
development path
The reason why we have been able to multiply so far is largely inseparable from our ability to focus on listening. For example, when our ancestors were hunting, they used sound to track and find food to maintain the livelihood of the family or the village. With the help of sound, they can locate potentially deadly factors in a 3D immersive way, thereby avoiding predators. As long as we hear the sound, we can perceive which direction it is in, how far away it is from us, and how fast it is approaching.
Immersive audio is a high-tech audio processing and sound technology. Its realization is inseparable from high-quality audio processing, as well as a series of carefully designed, calibrated and arranged high, medium and woofer speaker units, so as to provide dynamic Full spectrum auditory experience.
Although ordinary enthusiasts in the past did not pursue such a configuration, movie theaters and various performance venues have been using this technology for many years. Like all pioneering technologies, it will eventually find its own way to benefit other fields.
Modern entertainment systems will use many specialized filters and dynamic processing to create solutions that can be affordable for more people. Today, the popularity of home theaters has reached a new high, and the rampant new crown epidemic has further promoted this trend. In the ubiquitous game equipment and home theaters, immersive audio is a logical need.
Although stereo can achieve basic surround sound capabilities, Dolby Digital 5.1 (Dolby Digital 5.1) technology is the most widely used surround sound and 3D audio solution today. Such systems include Dolby Digital, Dolby Pro Logic II (Dolby Pro Logic II), DTS, SDDS and THX and other technologies. They all use a six-speaker configuration (five full-bandwidth channels, one subwoofer) arranged around the listener )(figure 1). These surround sound technologies were first applied in movie theaters, which promoted their further development and reduced the cost to a level acceptable to the public.
Figure 1: 5.1 surround sound uses five full-range speakers placed in specific locations and a subwoofer. Audio processing engineers can mix the sound to make the listener feel that the sound seems to move around them. The subwoofer can usually be placed anywhere. (Photo source: Zern Liew/Shutterstock.com)
In such a system, multiple speakers are driven by independent audio streams, so that listeners can feel virtual sound surrounding themselves. Among them, the left rear and right rear channels are responsible for the spatial depth; the left front, right front and front center channels are responsible for the horizontal depth; the subwoofer is responsible for the low frequency sound of the entire space.
For a single listener in the center of the listening area (that is, the sofa), this configuration is ideal. In the case of multi-person listening, there will be slight differences in the experience of the listeners in different positions, but overall they are relatively consistent, and everyone can feel the movement of the sound. Nowadays, some sound engineers have provided 5.1 surround sound tracks in their new records and promoted them as “immersive”.
An interesting fact is that the front center channel is optimized for the voice range of the sound, which helps the listener to be able to distinguish between the characters and the dialogue while immersed in the 3D sound effects. As rich and thick voices become more and more popular, it will become more difficult to distinguish human voices. Through the filtering and amplification of the center channel, it is easier for the listener to hear the dialogue of the characters.
On the basis of 5.1 surround sound, if the left and right rear channels are cancelled and replaced with left surround, right surround and rear center channels, it can be upgraded to 6.1 surround sound (Figure 2); if it is based on 6.1 surround sound Cancel the rear center channel, change to the left and right rear channels, it becomes 7.1 surround sound (Figure 3).
Figure 2: 6.1 Surround sound is equipped with speakers on the left and right sides, which can enhance the mobile sound effect when the audio object moves from the front to the side or the back. The subwoofer can still be placed at will, and the topic of bass is not discussed here. (Photo source: Zern Liew/Shutterstock.com)
7.1 surround sound technology adds more speakers and independent channels, so a 2.5D cubic or polygonal sound field can be constructed, with more high, mid, and woofers in important positions, so that the listener can be immersed in 2D and limited 3D audio (image 3). For the sound effect from directly above or below the listener, it can be approximated by signal processing to a certain extent, but it cannot achieve a perfect effect unless there is a speaker above or below.
Figure 3: Placing more speakers at a smaller angle helps eliminate possible audio hotspots, especially if the audio track is not properly mixed or processed, or the audio converter fails to properly handle surround sound. (Photo source: Zern Liew/Shutterstock.com)
It is worth noting that we can process the picked-up stereo audio signal through the audio source converter to create a synthesized multi-speaker surround sound signal. In other words, only with the help of digital signal processing technology, we can largely separate the location of the sound source from the stereo. Of course, the most ideal solution for 3D audio is still to pick up the sound through a 3D microphone, and then use the same 3D speaker configuration to play it, but this approach is troublesome and difficult, and since the signal processing can achieve a very similar effect, it is Few people will toss like this.
But is signal processing really a panacea? Our keen sense of hearing can be fooled by signal processing and a limited number of speakers? If this is not the case, do we have to use wall-to-ceiling speakers?
Figure 4: There is an old saying that “the more the better.” Many artists like to equip a lot of speakers and amplifiers on site. This may be necessary in large outdoor performances, but do you really want to cover the entire wall with speakers? In some cases, do you prefer to experience better sound effects than louder volume? (Photo source: tommistock/Shutterstock.com)
Object-oriented audio
The latest practice of immersive audio comes from Dolby Atmos, which was originally designed for cinema applications. So far, nearly 5,000 theaters have been transformed to bring this new listening experience through 64 speakers. The technology supports a large array of up to 128 channels, which can use full range, bass, subwoofer and tweeter.
Unlike traditional audio, Dolby Atmos (and its competitor Sony 360) uses the concept of “audio objects”. The audiovisual receiver (AVR) will automatically adapt the number, type and position of speakers, and process the spectral composition, amplitude position, speed and direction of each audio object. However, the “audio object” does not only contain the sound itself, it also carries various metadata to help the object audio renderer (OAR) move the object. Of the 128 channels, 10 are used for environmental effects, and the remaining 118 can be used for audio objects.
These channels do not necessarily correspond to specific speakers. The channel information corresponds to the sound object, and the object audio can be processed, combined with other object audio, and finally distributed to each speaker at an appropriate volume. Throughout the process, AVR uses metadata to process the signal in real time, and perform real-time mixing and distribution.
It is conceivable that this kind of technology is not like stereo, as long as you put two speakers at hand, it can be realized. For Dolby Atmos and many other surround sound and 3D sound systems, the speakers must be calibrated after they are placed in order to collectively present an accurate sound field. Dolby Atmos also has a program suitable for home theater, but not all 128 channels are used. This home solution should be configured with 34 speakers.
Dolby Atmos is not completely new. In 2012, a theater in Los Angeles hosted the premiere of a Disney movie, which was the first practical application of the technology. Since then, large theaters, IMAX, planetariums, musicals, theater, and other audio applications have actively adopted this technology, making it the de facto audio pickup standard for new movies and events. Dolby Atmos also builds a complete sound hemisphere through the speakers on the ceiling, which not only makes the sound really come out from above, but also makes real-time processing easier.
Once upon a time, Dolby Atmos was too complicated and expensive for ordinary enthusiasts, but now for enthusiasts with enough space and budget, it has become a must-have configuration that amazes friends, with a five-star rating.
If you have already spent a lot of money on other surround sound technologies, you can also start with a Dolby Atmos converter and continue to use your existing speakers and amplifiers. However, you will not stop there, at least you definitely want to have ceiling speakers. This converter can convert Dolby 5.1 into a 7.4.1 surround sound configuration with 17 speakers.
It is worth noting that Dolby Atmos can also be achieved through sound bars instead of surround speakers. Various forms of soundbar technology are becoming more and more popular. Obvious advantages such as reduced costs, simplified settings, reduced power consumption, reduced cables, and reduced size have promoted the development of this technology.
Phased array vertical sound bars have proven that they can simulate the complete audio spectrum with good clarity and separation. Musicians who use them will tell you that a soundbar column with 6-inch speakers can provide the equivalent of 18-inch speakers for subwoofer applications. This should be enough to attract some people’s attention. Therefore, horizontal soundbars and soundbar-based hybrid systems (including remote speakers) are popular in many home theaters and studios.
The top speakers and side speakers of the soundbar make the sound reflect on the wall and ceiling surfaces, making the listener feel as if it comes from above and behind. The modern Tesla Model 3 uses the front soundbar technology as part of its 15-speaker audio system, thus making surround sound and immersive audio a selling point. Turn off the rear speakers of the Model 3 and enable the immersive audio mode with signal processing and reverberation to experience this feature. Those who have tried it firmly believe that the sound comes from behind. However, its actual feedback is mixed, and many people don’t like such sound effects. The views of the assessors also show a tendency of polarization, many of which mentioned that different types of music are suitable or not suitable for soundbar-style immersive solutions. This makes sense, because the quality of sound reproduction is inseparable from the mixing technique of the sound engineer. The ability of the sound bar to land successfully in this scenario means that accurate, immersive speaker technology with up and down directions can almost be achieved without floor and ceiling speakers.
Pick and render
Immersive video experiences such as games use a completely created environment composed of 3D structures with surface rendering and specified physical properties. Real video clips can be captured and digitally stitched together to form a panorama including upper and lower images.
Immersive experiences, such as walking in a national park, can integrate rich visual effects, and audio can be synthesized or created by combining pre-recorded clips. These clips can be picked up in a 3D sound system and used as part of an immersive experience. Just like video controlled by head tracking, audio must also be controlled by head tracking. For example, when you face a gurgling creek, the sound you hear will be significantly different from when you face it with your back. If there is no head tracking to control the sound, the immersive experience will be greatly reduced.
Fortunately, you don’t have to invent a 3D audio pickup solution for immersive purposes. Well-known audio manufacturers such as Sennheiser have used segmented axes and digital tools to create professional truly omnidirectional microphones to pick up highly directional sounds (Figure 5). AMBEO VR Mic contains multiple sensitive wide-spectrum microphone elements and uses a surround sound configuration. DearVR MICRO processing software can render directional audio to provide a standard surround sound configuration.
Figure 5: Sennheiser AMBEO VR Mic and other immersive audio pickup technologies enable the digital audio engine to render the sound field according to the geomagnetic pole and direction. Through digital summation, it is possible to create composite audio that combines multiple sound sources at different distances. (Source: Sennheiser)
For this, the audio engine needs to know the direction and movement of your head. According to today’s standards, this is easy to achieve when using head-mounted display devices, because they all have a built-in head tracking function for video rendering. But how can an immersive audio system based on head position be realized through headphones limited to two ears? We can place multiple miniature speakers in the headset to simulate the surround sound experience. For most applications, stereo is sufficient, but it is still not at the same level as true surround sound.
Non-entertainment applications
Although immersive audio-visual technology is used for entertainment purposes in most cases, it also has a place in professional use. For example, product design engineering can benefit from immersive technologies including video and audio. From a video perspective, the mechanical design of complex components can be constructed, rendered, and inspected in a virtual way. For virtual components generated in an immersive manner, such as jet engines, we can build, push in, and inspect them immersively to ensure gears and turbines are aligned. Factory experts immersed in the manufacturing environment can guide maintenance technicians on the other side of the world.
Immersive audio can also help in engineering applications. The engineering team designing the car can hear the simulated rendered engine and gearbox noise. They can extract environmental control elements such as airflow, vibration, and swing from the virtual design. They can also design and test the car windows in the virtual environment to avoid popping when the car windows are rolled to a specific position at a specific speed – this It is a problem that still occurs in many new cars today.
In various use cases, audio is part of an immersive experience, but not all situations require surround sound. At least until the real surround sound problem is solved with binaural headphones, simulated surround sound may be sufficient.
Author: Jon Gabay
introduction
The world is constantly changing. This state of continuous development means that the way we interact with the world, equipment, and others is also changing. In addition to profit, there are two important forces that dominate this change: one is the development of technology, which promotes our continuous innovation and brings a variety of devices and applications that we are accustomed to today; , It is driven by the new crown epidemic that people are more concerned about their health.
When people have more time for entertainment, immersive technology ushered in development opportunities. Consumers can now purchase virtual reality and augmented reality headsets from many manufacturers, and amateur developers and professionals can also use development tools to render virtual worlds and scenes. These display technologies are hitting media headlines from time to time, and at the same time the corresponding audio technology has not been left behind.
Among the five recognized perceptions, sound may be the first that people feel. Whether it is the abundance of nature, the richness of orchestral music, or the agitation of spiritual songs, sound, like any other perception, will have a profound impact on our emotions and physiology.
development path
The reason why we have been able to multiply so far is largely inseparable from our ability to focus on listening. For example, when our ancestors were hunting, they used sound to track and find food to maintain the livelihood of the family or the village. With the help of sound, they can locate potentially deadly factors in a 3D immersive way, thereby avoiding predators. As long as we hear the sound, we can perceive which direction it is in, how far away it is from us, and how fast it is approaching.
Immersive audio is a high-tech audio processing and sound technology. Its realization is inseparable from high-quality audio processing, as well as a series of carefully designed, calibrated and arranged high, medium and woofer speaker units, so as to provide dynamic Full spectrum auditory experience.
Although ordinary enthusiasts in the past did not pursue such a configuration, movie theaters and various performance venues have been using this technology for many years. Like all pioneering technologies, it will eventually find its own way to benefit other fields.
Modern entertainment systems will use many specialized filters and dynamic processing to create solutions that can be affordable for more people. Today, the popularity of home theaters has reached a new high, and the rampant new crown epidemic has further promoted this trend. In the ubiquitous game equipment and home theaters, immersive audio is a logical need.
Although stereo can achieve basic surround sound capabilities, Dolby Digital 5.1 (Dolby Digital 5.1) technology is the most widely used surround sound and 3D audio solution today. Such systems include Dolby Digital, Dolby Pro Logic II (Dolby Pro Logic II), DTS, SDDS and THX and other technologies, all of which use a six-speaker configuration (five full-bandwidth channels, one subwoofer) arranged around the listener )(figure 1). These surround sound technologies were first applied in movie theaters, which promoted their further development and reduced the cost to a level acceptable to the public.
Figure 1: 5.1 surround sound uses five full-range speakers placed in specific locations and a subwoofer. Audio processing engineers can mix the sound to make the listener feel that the sound seems to move around them. The subwoofer can usually be placed anywhere. (Photo source: Zern Liew/Shutterstock.com)
In such a system, multiple speakers are driven by independent audio streams, so that listeners can feel virtual sound surrounding themselves. Among them, the left rear and right rear channels are responsible for the spatial depth; the left front, right front and front center channels are responsible for the horizontal depth; the subwoofer is responsible for the low frequency sound of the entire space.
For a single listener in the center of the listening area (that is, the sofa), this configuration is ideal. In the case of multi-person listening, there will be slight differences in the experience of the listeners in different positions, but overall they are relatively consistent, and everyone can feel the movement of the sound. Nowadays, some sound engineers have provided 5.1 surround sound tracks in their new records and promoted them as “immersive”.
An interesting fact is that the front center channel is optimized for the voice range of the sound, which helps the listener to be able to distinguish the dialogue of the characters while immersing in the 3D sound effects. When rich and thick voices become more and more popular, it will become more difficult to distinguish human voices. Through the filtering and amplification of the center channel, it is easier for the audience to hear the dialogue between the characters.
On the basis of 5.1 surround sound, if the left and right rear channels are cancelled and replaced with left surround, right surround and rear center channels, it can be upgraded to 6.1 surround sound (Figure 2); if it is based on 6.1 surround sound Cancel the rear center channel, change to the left and right rear channels, it becomes 7.1 surround sound (Figure 3).
Figure 2: 6.1 Surround sound is equipped with speakers on the left and right sides, which can enhance the mobile sound effect when the audio object moves from the front to the side or the back. The subwoofer can still be placed at will, and the topic of bass is not discussed here. (Photo source: Zern Liew/Shutterstock.com)
7.1 surround sound technology adds more speakers and independent channels, so a 2.5D cubic or polygonal sound field can be constructed, with more high, mid, and woofers in important positions, so that the listener can be immersed in 2D and limited 3D audio (image 3). For the sound effect emitted from directly above or below the listener, to a certain extent, it can be approximated by signal processing, but it cannot achieve a perfect effect unless there is a speaker above or below.
Figure 3: Placing more speakers at a smaller angle helps eliminate possible audio hotspots, especially if the audio track is not properly mixed or processed, or the audio converter fails to properly handle surround sound. (Photo source: Zern Liew/Shutterstock.com)
It is worth noting that we can process the picked-up stereo audio signal through the audio source converter to create a synthesized multi-speaker surround sound signal. In other words, only with the help of digital signal processing technology, we can largely separate the location of the sound source from the stereo. Of course, the most ideal solution for 3D audio is still to pick up the sound through a 3D microphone, and then use the same 3D speaker configuration to play it, but this approach is troublesome and difficult, and since the signal processing can achieve a very similar effect, it is Few people will toss like this.
But is signal processing really a panacea? Our keen sense of hearing can be fooled just by signal processing and a limited number of speakers? If this is not the case, do we have to use full-wall, full-ceiling speakers?
Figure 4: There is an old saying called “More is better.” Many artists like to equip a lot of speakers and amplifiers on site. This may be necessary in large outdoor performances, but do you really want to cover the entire wall with speakers? In some cases, do you prefer to experience better sound effects than louder volume? (Photo source: tommistock/Shutterstock.com)
Object-oriented audio
The latest practice of immersive audio comes from Dolby Atmos, which was originally designed for cinema applications. So far, nearly 5,000 theaters have been transformed to bring this new listening experience through 64 speakers. The technology supports a large array of up to 128 channels, which can use full range, bass, subwoofer and tweeter.
Unlike traditional audio, Dolby Atmos (and its competitor Sony 360) uses the concept of “audio objects”. The audiovisual receiver (AVR) will automatically adapt the number, type and position of speakers, and process the spectral composition, amplitude position, speed and direction of each audio object. However, the “audio object” does not only contain the sound itself, it also carries various metadata to help the object audio renderer (OAR) move the object. Of the 128 channels, 10 are used for environmental effects, and the remaining 118 can be used for audio objects.
These channels do not necessarily correspond to specific speakers. The channel information corresponds to the sound object, and the object audio can be processed, combined with other object audio, and finally distributed to each speaker at an appropriate volume. Throughout the process, AVR uses metadata to process the signal in real time, and perform real-time mixing and distribution.
It is conceivable that this kind of technology is not like stereo, as long as you put two speakers at hand, it can be realized. For Dolby Atmos and many other surround sound and 3D sound systems, the speakers must be calibrated after they are placed in order to collectively present an accurate sound field. Dolby Atmos also has a program suitable for home theater, but not all 128 channels are used. This home solution should be configured with 34 speakers.
Dolby Atmos is not entirely new. In 2012, a theater in Los Angeles hosted the premiere of a Disney movie, which was the first practical application of the technology. Since then, large theaters, IMAX, planetariums, musicals, theater, and other audio applications have actively adopted this technology, making it the de facto audio pickup standard for new movies and events. Dolby Atmos also builds a complete sound hemisphere through the speakers on the ceiling, which not only makes the sound really come out from above, but also makes real-time processing easier.
Once upon a time, Dolby Atmos was too complicated and expensive for ordinary enthusiasts, but now for enthusiasts with enough space and budget, it has become a must-have configuration that amazes friends, with a five-star rating.
If you have already spent a lot of money on other surround sound technologies, you can also start with a Dolby Atmos converter and continue to use your existing speakers and amplifiers. However, you will not stop there, at least you definitely want to have ceiling speakers. This converter can convert Dolby 5.1 into a 7.4.1 surround sound configuration with 17 speakers.
It is worth noting that Dolby Atmos can also be achieved through sound bars instead of surround speakers. Various forms of soundbar technology are becoming more and more popular. Obvious advantages such as reduced costs, simplified settings, reduced power consumption, reduced cables, and reduced size have promoted the development of this technology.
Phased array vertical sound bars have proven that they can simulate the complete audio spectrum with good clarity and separation. Musicians who use them will tell you that a soundbar column with 6-inch speakers can provide the equivalent of 18-inch speakers for subwoofer applications. This should be enough to attract some people’s attention. Therefore, horizontal soundbars and soundbar-based hybrid systems (including remote speakers) are popular in many home theaters and studios.
The top speakers and side speakers of the soundbar make the sound reflect on the wall and ceiling surfaces, making the listener feel as if it is coming from above and behind. The modern Tesla Model 3 uses the front soundbar technology as part of its 15-speaker audio system, thus making surround sound and immersive audio a selling point. Turn off the rear speakers of the Model 3 and enable the immersive audio mode with signal processing and reverberation to experience this feature. Those who have tried it firmly believe that the sound comes from behind. However, its actual feedback is mixed, and many people don’t like such sound effects. The views of the assessors also show a polarization trend, many of which mentioned that different types of music are suitable or not suitable for soundbar-style immersive solutions. This makes sense, because the quality of sound reproduction is inseparable from the mixing technique of the sound engineer. The ability of the sound bar to land successfully in this scenario means that accurate, immersive speaker technology with up and down directions can almost be achieved without floor and ceiling speakers.
Pick and render
Immersive video experiences such as games use a completely created environment composed of 3D structures with surface rendering and specified physical properties. Real video clips can be captured and digitally stitched together to form a panorama including upper and lower images.
Immersive experiences, such as walking in a national park, can integrate rich visual effects, and audio can be synthesized or created by combining pre-recorded clips. These clips can be picked up in a 3D sound system and used as part of an immersive experience. Just like video controlled by head tracking, audio must also be controlled by head tracking. For example, when you face a gurgling creek, the sound you hear will be significantly different from when you face it with your back. If there is no head tracking to control the sound, the immersive experience will be greatly reduced.
Fortunately, you don’t have to invent your own 3D audio pickup solution for immersive purposes. Well-known audio manufacturers such as Sennheiser have used segmented axes and digital tools to create professional truly omnidirectional microphones to pick up highly directional sounds (Figure 5). AMBEO VR Mic contains multiple sensitive wide-spectrum microphone elements and uses a surround sound configuration. DearVR MICRO processing software can render directional audio to provide a standard surround sound configuration.
Figure 5: Sennheiser AMBEO VR Mic and other immersive audio pickup technologies enable the digital audio engine to render the sound field according to the geomagnetic pole and direction. Through digital summation, it is possible to create composite audio that combines multiple sound sources at different distances. (Source: Sennheiser)
For this, the audio engine needs to know the direction and movement of your head. According to today’s standards, this is easy to achieve when using head-mounted display devices, because they all have a built-in head tracking function for video rendering. But how can an immersive audio system based on head position be realized through headphones limited to two ears? We can place multiple miniature speakers in the headset to simulate the surround sound experience. For most applications, stereo is sufficient, but it is still not on the same level as true surround sound.
Non-entertainment applications
Although immersive audio-visual technology is used for entertainment purposes in most cases, it also has a place in professional use. For example, product design engineering can benefit from immersive technologies including video and audio. From a video perspective, the mechanical design of complex components can be constructed, rendered, and inspected in a virtual way. For virtual components generated in an immersive manner, such as jet engines, we can build, push in, and inspect them immersively to ensure gears and turbines are aligned. Factory experts immersed in the manufacturing environment can guide maintenance technicians on the other side of the world.
Immersive audio can also help in engineering applications. The engineering team designing the car can hear the simulated rendered engine and gearbox noise. They can extract environmental control elements such as airflow, vibration, and swing from the virtual design. They can also design and test the car windows in the virtual environment to avoid popping when the car windows are rolled to a specific position at a specific speed – this It is a problem that still occurs in many new cars today.
In a variety of use cases, audio is part of an immersive experience, but not all situations require surround sound. At least until the real surround sound problem is solved with binaural headphones, simulated surround sound may be sufficient.
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