Artificial Reverberation

Each Virtual Room in SPAT can have its own artificial reverberation. Reverberation is essential in the psycho-acoustic perception of localized sources and immersive sound fields. The reverb processor in SPAT is a multichannel algorithmic 3D reverb based on feedback delay networks. The SPAT reverberation engine is designed to synthesize the experience of the virtual sources and the listener, all being placed within the same virtual acoustic space. Virtual spaces can be tuned, scaled, and stored. Open the Artificial Reverberation graphical editor by clicking on the Reverb at the bottom of the list of sources on the left side panel of the Room.

Internally, the SPAT Revolution reverb engine models many technical acoustic parameters, but the user interface has been simplified a great deal to make artificial reverb design more straightforward and functional.

Note

Some Spat Reverb parameters control how the acoustics are perceived.

Alongside conventional tuning parameters, which you might be familiar with, you will also find perceptual parameters, such as heaviness, liveness and presence.

These Perceptual Reverb parameters have been derived from the same IRCAM research experiments which were used to define the Perceptual Factors 28.2 of sources such as warmth, envelopment and brilliance. These can be found among the parameters for each virtual source.

The SPAT reverb designer can be used for much more than only simulating a “normal” acoustic space. For example, you could design an unreal space with continuously modulating acoustic properties or infinite reverberation.

Note

Try to switch the Infinite option for an immediately impressive immersive effect.

Reverb Parameters

Every variable of the Virtual Room reverberation can be directly edited through the onscreen controls in real-time.

The reverb designer excels at creating static acoustic settings that add dimensionality and immersive depth to a virtual scene. It also invites more creative reverberation ideas. Remember, it works in 3D and interacts deeply with the parametric design of all virtual objects that are expressed through it.

This is no ordinary reverb.

The SPAT Reverb is a true acoustic modeling multichannel reverb, not just a so-called true stereo reverb. Despite its internal complexity, the user is invited to morph and modulate the characteristics of the virtual acoustics. To make this process fluid and natural, the parameter controls have been carefully designed so that they do not glitch. This invites continuous parametric modulation ideas for designing out-of-this-world reverberant spaces in real-time.

Reverb Design Presets

The Artificial Reverberation editor has its own preset management system, where you can save pre-designed models into a user-defined preset list or to disk.

This is useful for building up a collection of pre-designed reverberation spaces and for designing models that might closely match the measurements of actual spaces you already know.

Reverb General

Reverb enable

Turn on/off the entire reverberation engine for the room. All sources’ components (early, cluster, and tail) will be affected.

Tail

Turn on/off the tail of the reverberation engine for the room.

Reverb Density

Internally, spatial variations are computed using a kind of 3D network of reverb, and this setting toggles between an 8x8 (standard) or 16x16 size (high). The choice of which sounds best is left up to you, as this depends on the source material at hand. However, it must be emphasized that the high-density setting consumes fairly more CPU and that the color of the reverb can be altered by this setting, particularly at some extreme parameter setting combinations.

Size

This is a meta-parameter that takes care of several other parameters to quickly set the equivalent size of the virtual room, adjusting early, cluster, and tail reverb parameters to match the room characteristics.

Reverb Start

Reverb start sets the duration between the direct, dry source signal, and the first late reflections, or beginning of the reverb tail.

Note

Please note that its value can never go below the cluster minimum time, as the reverb tail is fed with a signal derived from the cluster section.

Perceptual Factors

Reverberance

Reverberance affects how the listener perceives the music to be prolonged by the reverb when the musical message suddenly stops. The effect of this setting is also apparent when the source material is percussive. Reverberence is tightly related to the overall decay time of mid-frequencies, which is the time the late reflections take to vanish into silence.

Heaviness

The relative decay time of low-frequency content.

Liveness

The relative decay time of high-frequency content. Describes the liveliness and movement associated with the reverb tail (late reflections).

Room Response Parameters

Early refers to the Early Reflections stage of the Room response, one of the most significant stages involved in our rapid aural perception of spatial properties and sound source localization.

Cluster refers to a secondary iteration of room response reflections and is significant in the cognition of room acoustics.

Tail refers to the diffuse reverberations that eventually decay in a direct relationship with the size and reflectivity of an acoustic space. The tail section of a reverb does not contribute much to the localizability of a sound source in a space, but instead gives a sense of depth and ambiance.

Early Min

Early reflections minimum time, i.e., the time at which the early reflections appear, in milliseconds. This is a similar setting to the ubiquitous “pre-delay” found on most reverberation processors. It represents the time between the direct sound and the first early reflection.

Early Max

Early reflections maximum time, i.e., the time these cease to appear.

Early Dist

Early reflections’ distribution. Determines how early reflections are scattered in time, inside the Early Min. / Early Max. interval. The default setting of 0.5 corresponds to regularly spaced reflections; above, these are more grouped towards the Early Max. value, and vice versa.

Early Shape

Governs the amplitude rise or fall of early reflections. The default setting of 0.5 corresponds to early reflections, all having the same level. This mimics an acoustic space where reflective surfaces are located roughly the same distance from the listener. Below 0.5, early reflections decay with time; above 0.5, they rise with time. Decreasing levels of the early reflections would be typical of a space where most reflective surfaces are grouped at a range closest to the listener.

Cluster Min

See Early Min. Please remember that the cluster is fed with the input of the early reflections’ processor section, as shown on the display.

Cluster Max

See Early Max.

Cluster Distribution

See Early Distribution.

Options

Infinite

When activated, decay time temporarily rises to infinity, making the signal recirculate indefinitely inside the reverberation engine. This is best suited for on-off special effects such as “deep-freezing” audio material or if you want to create something somewhat less conventional than a fade-out for the end of your track.

Air Absorb

Simulates the frequency-dependent absorption of air, where high frequencies roll off quicker than low frequencies with respect to distance. You have probably noticed this real-world phenomenon when you are far away from a concert venue and can only hear the bass and gradually start to hear the whole mix as you get closer.

Abs. RollOff

Roll-off frequency for the air absorption simulation. Signal content above this frequency vanishes faster.

Crossover

Crossover L

Sets the frequency below which decay time is determined by the heaviness setting, expressed in Hertz (Hz). Default value: 177 Hz

Crossover H

Sets the frequency above which decay time is determined by the liveliness setting, expressed in Hertz (Hz). Default value: 5657 Hz