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How surround movie/music sound is made?

If you ever been to a classical concert you have probably seen this kind microphone set ups.

Have you wondering why need so many microphones?

To explain this we first need to discuss how we hear sounds. Although we only have two ears but they can hear sound up to 360 degrees and perceive the depth/distance of the sound objects. We can easily identify where the violins and double bass are located on the stage with our eyes closed.

Microphones were designed to hear sounds like our ears but they can only hear certain frequency ranges and limited depth and resolution. Not like our ears microphone can not pickup depth of the sound. Especially when a lot sounds are playing together. This is why they need many microphones to record different parts of the sounds. We put the microphones in certain layout to achieve the best recording result that is close to what we hear in the concert. Different microphone locations provides reference sound object depth when we combine them together. The result is to recreate the immersive sound experience like we were in the concert hall.

How about movies? Are they recorded using many microphones?

Movie sound recording is very different to the acoustic music recording. In fact movie sounds are recreated and reconstruct from isolate recorded sound parts in the studio instead recorded live. Every part of the movie sound are designed and created from scratch. They are divided into different groups. For example: Main characters dialogue, footsteps , environment sound, sound effects...etc. Below is Hugh Jackman re-record the sound for the movie "Logan"

So what's make it sound so real and immersive?

After sound producer collected all sound clips for the movie. All clips will then input to a mixing session. This is where film sound engineers and producer recreate the sounds for the movie. The process involve using a lot acoustic simulation(reverberation/delay.....etc) to recreated realistic sound experience.

After they finished the final combining the sound clips. Both Movie and music sound are delivered in two different ways to us. In order to be able to be play back and streaming online. The first and most popular way of delivery is two channels stereo audio. This can be DSD, wav, mp3, aac... etc. formats. This delivery is accessible to all of us and can be playback use our daily devices.

Another way of delivery is multichannel audio. This delivery usually included 6 to 13 channels of audio information for the equal amount of speakers to play back. It comes with name of WAV, AC3, DTS......etc. They will require special decoding device and many speakers to playback. The cost of the devices and speakers are much higher then the stereo speakers.

Both delivery methods contain the exactly same amount of audio sound information. Sometimes stereo has higher audio resolution due to smaller file size. The difference is the amount of speaker used to recreate the immersive experience to our ears. The multichannel audios delivery method split the sound information into many speakers that positioned surround listeners to achieve the multi directional sound source output. So we can hear the sound from different directions. However, This method makes the sound reproduction expensive and less accessible in normal daily situations.

This is why we don't use multi channels in our daily devices. We simply can not carry many speakers with us and have them layout correctly every time we want to play a song or watch a movie.

What we do in Preter Audio?

Since the stereo audio format contain the same audio sound information like the multichannel audio. The challenge is to recreate a multi directional audio from the stereo sound source. Preter Audio achieve this by using the walls, ceiling, and floors that every room already has. Our technology use the wall reflections efficiently to recreate the sound objects around the room.

With a good recorded and produced stereo audio source. Preter Audio speaker can recreate true 360 immersive front and rear surround sound in the room use just two units.


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