Ambisonics. A Q&A with Chat GPT.
Principles and practices of Ambisonics.
Q: What is ambisonic
ChatGPT:
Ambisonics is a technique used in audio engineering and sound recording to capture, reproduce, and manipulate sound in a three-dimensional space. The term "ambisonic" is derived from the words "ambi" (meaning "both" or "all") and "sonic" (related to sound). Ambisonics is designed to create a full-sphere sound field that can be played back through a multi-speaker setup or converted into various surround sound formats.
The primary idea behind ambisonics is to encode sound information using spherical harmonics, which mathematically represent the spatial properties of sound waves in a three-dimensional space. By capturing sound with multiple microphones or a specialized ambisonic microphone, the sound engineer can obtain not only the sound intensity but also the direction and position from which the sound is coming.
Ambisonic audio is often recorded using different channel configurations, such as first-order, second-order, or third-order ambisonics. Each order adds more spatial information, increasing the precision of sound placement. The higher the order, the more speakers are required for playback. For instance, first-order ambisonics uses four channels (W, X, Y, Z), while second-order has nine channels, and third-order has 16 channels.
During playback, ambisonics can be converted to various speaker layouts, like stereo, 5.1 surround sound, 7.1 surround sound, or even higher-order systems. This flexibility makes ambisonics a versatile technology for creating immersive soundscapes in various applications, such as virtual reality (VR), augmented reality (AR), 360-degree videos, gaming, and concert recordings.
In recent years, ambisonics has gained popularity due to the growing interest in spatial audio and the increasing availability of tools and platforms to process and render ambisonic content.
Q: How can I record and process ambisonic?
ChatGPT:
Recording and processing ambisonic audio involves several steps, including capturing the sound with an ambisonic microphone, encoding it in the desired format, and then processing or decoding it for playback or further manipulation. Here's a general overview of the process:
Recording with an Ambisonic Microphone: The first step is to capture the sound using an ambisonic microphone. Ambisonic microphones are designed to capture sound in all directions around the microphone, allowing you to record a complete 360-degree soundscape. These microphones typically have multiple capsules arranged in a specific pattern to capture the necessary spatial information.
Encoding the Ambisonic Audio: Once you have recorded the sound using the ambisonic microphone, the next step is to encode it in the ambisonic format. The most common format is first-order ambisonics, which consists of four channels: W, X, Y, and Z. Some ambisonic microphones may already provide output in this format, but if not, you will need to use specialized software to encode the recorded audio into ambisonics.
Processing the Ambisonic Audio: Ambisonic audio can be processed in various ways, such as spatial effects, sound positioning, and virtual sound source manipulation. This step involves using ambisonic processing tools or plugins to apply effects like reverb, panning, rotation, and spatialization. These tools allow you to shape the sound field and create immersive audio experiences.
Decoding for Playback: To play back the ambisonic audio, you will need a speaker setup that corresponds to the ambisonic format used during recording and processing. For example, a first-order ambisonic setup requires a minimum of four speakers positioned in a specific configuration to recreate the full 360-degree sound field.
Using Ambisonic Plugins and Software: There are various digital audio workstations (DAWs) and plugins available that support ambisonic audio processing. Some popular DAWs like Reaper, Ableton Live, and Pro Tools have ambisonic capabilities or can be extended with third-party plugins for ambisonic processing.
Working with Ambisonic in VR and 360-degree Content: Ambisonics is often used in virtual reality (VR) and 360-degree content production to provide realistic and immersive soundscapes. VR platforms and video players that support ambisonic audio can decode and render the spatial audio for a more engaging experience.
Keep in mind that working with ambisonic audio might require a learning curve, especially if you are new to spatial audio processing. Experimenting with different ambisonic tools, plugins, and configurations will help you gain a better understanding of how to create captivating immersive audio experiences.
Q: Ambisonic recordings in Logic Pro?
ChatGPT
As of my last knowledge update in September 2021, Logic Pro does not have native support for ambisonic audio. However, there are third-party plugins and tools that you can use to work with ambisonic recordings in Logic Pro. Here's a general guide on how to do it:
Acquiring an Ambisonic Recording: First, you need to record or obtain an ambisonic audio file using an ambisonic microphone or a dedicated ambisonic recorder. Make sure the file is encoded in the ambisonic format you wish to work with (e.g., first-order ambisonics with four channels: W, X, Y, Z).
Importing the Ambisonic File into Logic Pro: Open Logic Pro and import the ambisonic audio file into your project just like you would with any other audio file.
Third-Party Ambisonic Plugins: Since Logic Pro doesn't have built-in ambisonic support, you will need to use third-party plugins to work with ambisonic audio. Some popular ambisonic plugins include:
Ambi Head by Noise Makers: This plugin lets you position the listener's head within the 3D sound field, allowing for binaural monitoring of ambisonic content.
IEM AllRADecoder: This plugin allows you to decode ambisonic B-format recordings to various speaker configurations, including stereo and surround setups.
Creating an Ambisonic Bus: Set up an auxiliary channel strip in Logic Pro, and route the ambisonic audio to this bus. Then, insert the ambisonic plugin on this auxiliary channel.
Processing the Ambisonic Audio: Use the ambisonic plugin to apply spatial effects, rotate the sound field, and manipulate the sound source positions within the 360-degree sphere.
Monitoring Ambisonic Audio: Monitoring ambisonic audio can be challenging since it's meant to be experienced in a 360-degree sound field. One common approach is to use binaural monitoring with headphones. Some ambisonic plugins, like Ambi Head, offer binaural monitoring options to simulate the 3D sound field.
Exporting the Ambisonic Audio: Once you've processed the ambisonic audio to your satisfaction, you can export it for playback in ambisonic-capable media players, VR platforms, or 360-degree content.
Keep in mind that the availability and capabilities of third-party ambisonic plugins may change over time, so it's a good idea to check for the latest plugins and updates specific to ambisonic audio in Logic Pro. Additionally, if there have been updates to Logic Pro since my last knowledge update, it's possible that it may now include native support for ambisonic audio or improved third-party integration. Therefore, I recommend referring to the official Logic Pro documentation and community resources for the most up-to-date information.
Q: Do I need special headphones when working with ambisonic audio?
ChatGPT
Yes, when working with ambisonic audio, it is highly recommended to use special headphones designed for binaural monitoring. Regular stereo headphones are not suitable for accurately reproducing the three-dimensional sound field of ambisonic audio recordings.
Binaural monitoring headphones are designed to provide a more immersive listening experience by simulating the way sound reaches the ears in a natural environment. They take into account the individual's head-related transfer function (HRTF), which is the unique way each person perceives sound based on the shape and characteristics of their ears and head. By using binaural headphones with accurate HRTF modeling, you can better perceive the spatial cues in ambisonic audio.
With binaural monitoring, the ambisonic audio can be decoded and rendered in real-time to match how sound would be perceived if it were played through a 360-degree speaker setup. This helps audio engineers and producers make better spatial decisions during the production and post-processing stages.
Some ambisonic plugins, like the Ambi Head plugin mentioned in the previous answer, provide binaural monitoring options that can be used with standard stereo headphones. However, for the most accurate and realistic representation of ambisonic audio, dedicated binaural headphones are highly recommended.
When choosing binaural monitoring headphones, consider those that offer good sound quality, comfort for extended wear, and accurate HRTF modeling. Several manufacturers offer specialized binaural headphones suitable for ambisonic audio work. Always check the product specifications and reviews to ensure they meet your specific needs and preferences.
Q: How to pan for ambisonic effects?
ChatGPT
In the context of ambisonic audio, traditional panning techniques used in stereo or surround sound setups are not directly applicable. Instead, ambisonic audio employs a different approach to create spatial effects and sound positioning within the 360-degree sound field. This is done using rotation and decoding of ambisonic channels rather than traditional pan controls.
Here are some methods to achieve ambisonic effects:
Rotation of the Sound Field: To change the apparent direction of a sound source in ambisonic audio, you rotate the entire sound field. This means you adjust the azimuth and elevation angles of the virtual sound sources rather than just panning them left or right as in traditional stereo. This can be achieved using ambisonic rotation tools available in various ambisonic plugins.
Higher-Order Ambisonics (HOA) Decoding: Higher-order ambisonics use additional channels beyond the basic four (W, X, Y, Z) of first-order ambisonics. These additional channels provide more spatial detail and allow for more accurate sound positioning. By manipulating the HOA coefficients in the decoding process, you can change the perceived direction and position of sound sources in the 360-degree sound field.
Spatial Audio Effects Plugins: Some ambisonic plugins and tools provide specialized spatial audio effects that can be applied to ambisonic audio. These effects can include sound rotation, distance modeling, reverbs, Doppler effects, and more.
Automation and Animation: Ambisonic audio can be automated or animated to change the sound source positions dynamically over time. This can create the illusion of moving sound sources or evolving soundscapes in a 360-degree space.
Distance Modeling and Volume Attenuation: In ambisonics, distance modeling plays a crucial role in simulating the perceived loudness and directionality of a sound source based on its virtual distance from the listener. By adjusting the distance and volume attenuation parameters, you can make sounds appear closer or farther away in the 360-degree sound field.
Third-Party Ambisonic Plugins: To work effectively with ambisonic effects, consider using specialized third-party ambisonic plugins or software that offer tools for sound rotation, positioning, and spatial manipulation.
It's important to note that creating compelling ambisonic effects requires an understanding of ambisonic principles and experience with ambisonic processing tools. Experimentation and careful listening are essential to achieve the desired spatial effects in a 360-degree sound field.
Q: What are ambisonic principles and some ambisonic processing tools?
ChatGPT
Ambisonic Principles: Ambisonics is based on certain principles that govern how sound is recorded, encoded, and decoded to create a realistic and immersive 360-degree sound field. Some key principles of ambisonics include:
Spherical Harmonics: Ambisonics uses spherical harmonics to represent the spatial properties of sound waves in three-dimensional space. Spherical harmonics are mathematical functions that describe the direction and intensity of sound sources relative to a central point (the listener).
B-Format Encoding: Ambisonics uses B-format encoding to store sound information. B-format consists of four channels: W (omnidirectional), X (front-to-back), Y (left-to-right), and Z (up-and-down). These channels capture the intensity and directionality of sound in a spherical coordinate system.
Spatial Decoding: During playback, the B-format ambisonic audio is decoded and converted to the appropriate speaker configuration or binaural output to create the illusion of sound sources positioned around the listener.
Higher-Order Ambisonics (HOA): Ambisonics can be extended to higher orders beyond the first order (four channels) to capture more spatial detail. Second-order (nine channels) and third-order (16 channels) ambisonics offer increased precision and accuracy in sound positioning.
Ambisonic Processing Tools: To work with ambisonic audio, you'll need specialized plugins and software that can encode, decode, and process ambisonic audio. Here are some popular ambisonic processing tools:
Facebook 360 Spatial Workstation: This is a set of free tools provided by Facebook for spatial audio production. It includes plugins for encoding, decoding, and monitoring ambisonic audio in various formats.
Blue Ripple Sound:
Harpex-B: A high-quality B-format to binaural decoder, useful for monitoring ambisonic audio with headphones.
Harpex-X: A B-format to stereo or surround sound decoder.
IEM AllRADecoder: A flexible and powerful B-format to speaker array decoder developed by the Institute of Electronic Music and Acoustics (IEM) in Graz, Austria.
Noise Makers:
Ambi Head: A binaural monitoring plugin that allows you to position the listener's head in the 3D sound field.
Ambi Pan: A plugin for rotating and positioning ambisonic audio.
SPARTA: Spatial Audio Reproduction Toolbox: An open-source software package for spatial audio processing and research. It includes tools for ambisonic encoding, decoding, and more.
DearVR PRO: While primarily focused on virtual reality (VR) and 360-degree audio, this plugin suite offers spatial processing that can be used for ambisonics.
Reaper with Ambisonic Toolkit (ATK): Reaper is a digital audio workstation (DAW) that can be extended with the Ambisonic Toolkit (ATK) for ambisonic processing.
Please note that the availability and capabilities of ambisonic processing tools may change over time, and new tools may emerge as technology advances. It's always a good idea to research and explore the latest options for ambisonic processing to find the tools that best suit your needs and workflow.
Q: Can I mix stereo audio to be ambisonic?
ChatGPT
Yes, you can convert stereo audio into ambisonic format, but it won't provide true 360-degree spatial information as you would get from a dedicated ambisonic recording. Instead, it involves encoding the stereo audio into ambisonics, which essentially places the stereo content within the ambisonic sound field.
Here's how you can convert stereo audio into ambisonic:
Convert Stereo to B-Format: B-format is the format used to store ambisonic audio. To convert stereo audio into ambisonic, you need to encode the stereo signal into B-format. There are various ambisonic encoding algorithms, such as FuMa (First-order Ambisonic), AmbiX, and others. These algorithms convert the left and right channels of the stereo audio into the W, X, Y, and Z channels of the ambisonic B-format.
Choose the Ambisonic Order: Ambisonics come in different orders, from first-order (4 channels) to higher-order (e.g., second-order with 9 channels, third-order with 16 channels). The higher the order, the more spatial detail and accuracy you can capture. Choose the ambisonic order based on your specific requirements and the capabilities of your ambisonic processing tools.
Use Ambisonic Encoding Plugins: To convert stereo audio to ambisonic, you will need to use ambisonic encoding plugins or specialized software. These plugins take the stereo audio as input and generate the corresponding ambisonic B-format output.
Monitor in Binaural or Decode to Speakers: After encoding the stereo audio to ambisonic, you can monitor it using binaural headphones to simulate a 360-degree sound field. Alternatively, you can decode the ambisonic audio to a speaker array setup if you have the appropriate speaker configuration available.
It's essential to understand that the resulting ambisonic audio won't provide the same spatial accuracy as a dedicated ambisonic recording because the original stereo audio doesn't carry full 360-degree spatial information. However, it can still be useful for creating immersive audio experiences or integrating stereo content into ambisonic projects.
If you're working with stereo audio and want to incorporate ambisonic elements, you can consider blending stereo sounds with other ambisonic sources, such as ambisonic recordings or synthesized ambisonic soundscapes, to create more complex and spatially rich audio environments.
Q: Can I achieve ambisonic recordings without an ambisonic microphone?
ChatGPT
Yes, you can achieve ambisonic-like recordings without using a dedicated ambisonic microphone. While a true ambisonic microphone is designed to capture sound information in all directions simultaneously, you can still create a sense of spatial audio using a regular microphone and some post-processing techniques.
Here's how you can achieve ambisonic-like recordings without an ambisonic microphone:
Record Multiple Channels: Use multiple individual microphones to capture sound from different directions around the sound source. For example, you can set up a stereo pair or a surround microphone array to capture sound from various angles.
Record Room Impulse Responses (RIR): Record or obtain room impulse responses (RIR) for the space where the sound is recorded. RIR captures the acoustic characteristics of the environment, including reflections and reverb. This information can be used to add spatial cues during post-processing.
Create Spatial Audio Mix: In your digital audio workstation (DAW), import the individual microphone recordings as separate audio tracks. You can pan and position each track manually to represent the direction from which the sound is coming.
Add Reverb and Room Modeling: Use reverbs and room modeling plugins to simulate the acoustic characteristics of the environment. Apply different reverb settings and room simulations to each audio track to create a sense of spatial immersion.
Use Panning and Spatial Effects: Apply panning and spatial effects to individual tracks to position the sound sources around the listener. Techniques like stereo panning, surround panning, and rotation can help create a 360-degree sound field.
Encode to Ambisonics: Once you've processed and positioned the sound sources, you can encode the mix to ambisonics using specialized plugins or software. This process involves converting the spatial audio mix into ambisonic B-format, allowing you to work with the audio in a 360-degree sound field.
It's important to note that while these techniques can provide a sense of spatial audio, they won't match the accuracy and precision of a dedicated ambisonic microphone setup. A true ambisonic microphone captures sound information from all directions simultaneously, whereas multiple individual microphones and post-processing methods have limitations in capturing the full 360-degree sound field.
If you want to create high-fidelity ambisonic recordings, it's recommended to use a dedicated ambisonic microphone. However, the techniques mentioned above can still be useful for simulating spatial audio and creating immersive soundscapes in certain situations.
Q: Any recommended software for ambisonic sound design?
ChatGPT
There are several recommended software tools and plugins for ambisonic sound design, each offering different features and capabilities. Here are some popular options to consider:
Facebook 360 Spatial Workstation: This is a set of free tools provided by Facebook for spatial audio production. It includes plugins for encoding, decoding, and monitoring ambisonic audio in various formats. It's widely used for creating spatial audio for VR and 360-degree video projects.
Blue Ripple Sound:
Harpex-B: A high-quality B-format to binaural decoder, useful for monitoring ambisonic audio with headphones.
Harpex-X: A B-format to stereo or surround sound decoder.
IEM AllRADecoder: A flexible and powerful B-format to speaker array decoder developed by the Institute of Electronic Music and Acoustics (IEM) in Graz, Austria.
Noise Makers:
Ambi Head: A binaural monitoring plugin that allows you to position the listener's head in the 3D sound field for accurate binaural monitoring.
Ambi Pan: A plugin for rotating and positioning ambisonic audio.
SPARTA: Spatial Audio Reproduction Toolbox: An open-source software package for spatial audio processing and research. It includes tools for ambisonic encoding, decoding, and more.
DearVR PRO: While primarily focused on virtual reality (VR) and 360-degree audio, this plugin suite offers spatial processing that can be used for ambisonics.
Reaper with Ambisonic Toolkit (ATK): Reaper is a digital audio workstation (DAW) that can be extended with the Ambisonic Toolkit (ATK) for ambisonic processing.
Blue Ripple Sound:
Harpex-B: A high-quality B-format to binaural decoder, useful for monitoring ambisonic audio with headphones.
Harpex-X: A B-format to stereo or surround sound decoder.
Please note that the availability and capabilities of ambisonic sound design software may change over time, and new tools may emerge as technology advances. It's always a good idea to research and explore the latest options for ambisonic sound design to find the tools that best suit your needs and workflow. Additionally, some digital audio workstations (DAWs) like Nuendo and Reaper have native support for ambisonics or can be extended with third-party plugins, making them versatile options for ambisonic sound design.