RTC popular science video丨Talk about the principle of spatial audio and the acoustic principle behind it

In many online real-time interactive scenarios, we not only pay attention to the interactive experience, but also enhance the sense of immersion. In many scenarios, spatial audio technology alone can bring an immersive experience. What is the principle of spatial audio technology?

After watching our new RTC popular science video, you will know.

Spatial audio technology reconstructs the real sense of hearing in the digital world in an algorithmic way. Since it is reconstruction, to understand this process, we need to understand how we perceive the position of a sound in space through our ears and brain in reality.

To solve this problem, we can disassemble the process of judging the position of the sound, namely:

● How to judge the sound source and your horizontal position

● How to determine the sound source and your vertical orientation

● How to judge the distance between the sound source and you

In fact, we rely on the difference in volume, time and timbre between the ears to determine the direction of the sound. Since the two ears are located on both sides of the head, if the sound comes from the right side, the time it takes for it to reach the right ear is relatively shorter, which results in a binaural time difference; in the process of sound propagation, the frequency will be attenuated, so the distance between the two ears will be attenuated. The sound you hear will also be different.

In an indoor environment, the sounds heard by the ear include direct sound, early reflection sound, and late reverberation sound. The direct sound is literally the sound that is transmitted directly from the sound source to the ear; the early reflection is transmitted to the ear after being reflected by the indoor wall, which is 50-80ms later than the direct sound; the sound that arrives after the early reflection is Late reverb. As just said, there will be attenuation in sound propagation, so the distance between the sound source and the ear can be heard. Generally speaking, doubling the distance between the sound source and the ear will reduce the sound pressure of the direct sound by 50%, while the sound pressure of the early reflections and late reverberation will not be so significantly affected. Our brain will judge the distance of the sound source based on the sound pressure ratio of the direct sound to the early reflection + late reverberation.

In this popular science video, we explain the above principles. In order to allow more people to have a sense of picture and to imagine the process of sound transmission, we use "water" as an analogy. However, I would like to remind you again that the propagation of water waves is very different from the propagation of sound waves in the air.

In addition, we briefly explain how to reconstruct spatial audio in virtual reality (VR) in the video. We have not explained the algorithms mentioned in it in depth. If you are interested, you can check our previous articles .

Finally, if you still want to know what technical principles, please leave us a message.