Terminology: Sequence, Overlay, Stream, Sound, and Tone

In Erie, a stream is a unit specification for a sonification, similar to a facet or view in visualizations. Multiple streams can be combined as a sequence or an overlay (see the relevant documentations). Repeated stream (with a repeat channel in encoding) is still a stream or repeated stream. The term, sound, is an actual output audio. A tone is a unit sound that has no puase (except the pause between two tapping sounds) in it. For a continuous tone, itself is a sound; whereas for a discrete tone, it is multiple sounds compose a stream.

Composition

Erie offers two primary options for concatenation-based composition: sequence and overlay.

Sequence: concatenate streams serially

Multiple streams concatenated using sequence are played one by one.

{
  ...
  "sequence" : [
    { ... },
    { ... },
  ]
  ...
}

let stream1 = new Erie.Stream();
...
let stream2 = new Erie.Stream();
...

let sequence = new Erie.Sequence(stream1, stream2);
// alternatively
let sequence = new Erie.Sequence([stream1, stream2]);

Overlay: play streams parallelly

Multiple streams joined using overlay are played simultaneously together. Note: using a speech encoding channel may result in uncoordinated scheduling.

{
  ...
  "overlay" : [
    { ... },
    { ... },
  ]
  ...
}

let stream1 = new Erie.Stream();
...
let stream2 = new Erie.Stream();
...

let overlay = new Erie.Overlay(stream1, stream2);
// alternatively
let overlay = new Erie.Overlay([stream1, stream2]);

Patterns

Erie supports the following patterns for composing multiple streams.

• ✅ A sequence of overlays and/or streams
• ✅ An overlay of streams (without a repeat channel by overlay)

The following patterns are not supported (mostly because it may cause unexpected browser malfunctioning).

• ❌ An overlay of sequencess. Use sequences of overlay instead.
• ❌ An overlay of streams (with a repeat channel by overlay).