What is Ambisonic Sound?

Ambisonic sound is a type of immersive audio that allows listeners to feel as if they are inside the environment where the sound is coming from. It is commonly used in virtual reality (VR) applications, but can also be used in other types of media, such as video games and movies.

Ambisonic sound is created by placing microphones in strategic positions around the recording area or by using a specialised soundfield microphone that has multiple capsules to capture sound from all directions onto separate tracks. Capturing sound from all directions gives the listener a more realistic and immersive experience.

Another benefit of ambisonic sound is that it can create a more believable environment for listeners. This is because ambisonic sound takes into account the way humans hear sounds in real life. For example, when you are standing in a room, you not only hear sounds coming directly from in front of you, but also from the sides behind you and even above and below. Ambisonic sound captures this natural hearing process and replicates it, making it feel more true to real life.

Benefits of Ambisonic Sound

There are many benefits of Ambisonic sound for virtual reality, especially when it comes to immersive experiences. Here are just a few:

1. Spatialised audio gives the VR user a better sense of presence and immersion in the virtual environment.

2. Ambisonic sound can help create a more realistic and believable VR experience for the user which is especially useful when trying to invoke a specific emotional response for example creating fear and tension in a horror game.

3. Spatialised audio can also help with orienting the user in the virtual space, as well as providing auditory cues for events happening outside of their field of view.

4. Ambisonic sound can provide an enhanced sense of immersion and presence in VR by enveloping the listener in 360 degrees of audio.

Basics of VR Sound and How Ambisonics Works Within it

Virtual reality (VR) is a three-dimensional, computer-generated environment that can be explored and interacted with by a person. This immersive environment is created using a headset and sometimes glove-like controllers.

Sound is an important element in VR as it can help create immersion and a sense of presence. In traditional two-dimensional media, sound is usually recorded and played back from speakers placed around the room. However, this doesn't work as well in VR as the direction of sounds can change as the user's head moves. This can result in sounds coming from the wrong direction or not being audible at all if they are coming from behind the user.

Ambisonics is a system for recording, storing and reproducing 3D sound. It uses multiple audio channels to capture all of the information needed to recreate sound in three dimensions. These recordings are then played back through headphones or loudspeakers placed around the room, allowing the listener to experience sound coming from all directions, just as if they were there when it was recorded.

Ambisonics has been used in VR applications to create more realistic and immersive soundscapes. One example is using it to record ambisonic soundfields which can be played back through loudspeakers placed around the room, giving the listener a sense of being inside the recording.

Another example is using directional microphones to record sounds coming from different directions and then playing these back through headphones. This can give the listener a sense of direction.

3D Audio Formats and Methods

Most people are familiar with stereo audio, which is two channels of audio played back through either two speakers or headphones. In contrast, Ambisonic sound is recorded using four channels and requires special playback equipment.

There are several different Ambisonic sound formats, each with its own advantages and disadvantages. The most common format is First Order Ambisonics (FOA), which offers good sound quality and compatibility with existing stereo equipment. Higher order Ambisonic formats offer better sound quality but require more specialised playback equipment. Higher order Ambisonics mainly use B-format recordings, this means that each channel from the multichannel format does not correspond directly to a speaker feed, there needs to be a decoding step.

SoundField Microphone - Image Credit SoundField Website

There are several different methods for recording Ambisonic sound, including using microphone arrays and specialised Ambisonic microphones. The most common method is to use an omnidirectional microphone in conjunction with a SoundField microphone, which captures the direct sound and the reflections off of surfaces in the environment.

When played back, Ambisonic sound creates a three-dimensional soundscape that can be used to create a realistic sense of immersion in VR applications. The listener feels as if they are inside the recording space, surrounded by the sounds of the environment.

In addition to recording and playback, there are several Ambisonic sound processing techniques available to improve the realism of the experience. These include using reverberation and distance attenuation to create spatial echoes and realistic sound propagation.

Different Mixing Strategies for VR Surround Sound

With the release of Facebook's 360-degree spatial audio technology, Ambisonics has become one of the most popular methods for creating surround sound in virtual reality (VR). While traditional recording and mixing techniques are based on two channels (left and right), Ambisonics uses four channels (W, X, Y, Z) to capture a full sphere of sound. This allows for more realistic and immersive soundscapes in VR.

There are several different mixing strategies that can be used to create surround sound using Ambisonics. The three most common strategies are:

1. FuMA Mixing: FuMA is the standard mixing format for Ambisonics. It uses four channels (W, X, Y, Z) to represent the entire spherical soundfield. This allows for full control over the direction and level of each sound source.

2. First-Order Mixing: First-order Ambisonics uses only three channels (W, X, Y). This reduces the number of degrees of freedom and makes it more difficult to precisely control each sound source. However, first-order mixing is often sufficient for many VR applications.

3. Second-Order Mixing: Second-order Ambisonics uses five channels (W, X, Y, Z, R). This adds an additional degree of freedom that can be used to create more complex soundfields. Second-order mixing is typically only used for more advanced applications.

Decoding Software by Rode Image Credit - Rode Website

Depending on the project, different mixing strategies may be preferred for different types of VR sound. For example, FuMA mixing may be best for creating realistic and immersive audio experiences, while first-order or second-order mixing can be used to create more detailed soundscapes. Ultimately, the choice of which mixing strategy to use should be based on the end goal and creative vision of the sound designer.

Best Practices for Setting Up an Ambisonic Recording Setup

There are a few key things to keep in mind when setting up an Ambisonic recording setup:

1. Use a high quality microphone: This is crucial for getting the best possible sound quality. Ambisonic microphones are specially designed to pick up sound from all directions, so make sure to choose one that will suit your needs.

2. Position the microphone properly: The microphone should be placed at the center of the action, in the middle of the room or area you're trying to capture. This will ensure that it captures sound evenly from all directions.

3. Use multiple microphones: If you're recording with more than one person, it's best to use multiple microphones to capture each person's voice clearly. This way, you can avoid any bleed-over between different voices.

4. Make sure the audio is clean: Avoid any background noise or interference by making sure the recording environment is as quiet as possible. Any unwanted noise will only detract from the final product.

Advantages of Using Ambisonic Technology

There are many advantages to using Ambisonic technology for virtual reality applications. One of the biggest advantages is you are able to hear sounds coming from all directions, it helps your brain to better process and understand the virtual environment you are in. This can lead to a deeper level of immersion and connection with the VR world.

Another big advantage of Ambisonic sound is that it is much less likely to cause nausea or discomfort than traditional stereo sound. This is because Ambisonic sound provides a more natural and lifelike auditory experience. It can also help to reduce motion sickness by allowing your brain to better process movement within the VR environment.

Finally, Ambisonic technology is relatively easy to set up and use. Most VR headsets on the market today support Ambisonic sound, so you won't need any special equipment or knowledge to get started. You can simply turn on your VR headset and enjoy an immersive, realistic audio experience without any hassle.

Conclusion

To wrap it up, understanding the basics of ambisonic sound is a good starting point for those who are entering the world of Virtual Reality. It's important to remember that while ambisonics can be viewed as a complex audio field solution, when used properly, this type of technology can really bring an immersive experience and realistic 3D sound dimension to virtual reality applications. With its rich features and high definition capabilities, Ambisonics offers one of the best ways to make your VR projects come alive with sound you'll love experiencing.

Breaking Down the Basics of Ambisonic Sound for Virtual Reality