1     Functions

2     Reference Model

3     I/O Data of AI Workflow

4     Functions of AI Modules

5     I/O Data of AI Modules

6     AIW, AIMs and JSON Metadata

1      Functions

The goal of this use case is to restore a Damaged Segment of an Audio Segment containing only speech from a single speaker. The damage may affect the entire segment, or only part of it.

Restoration will not involve filtering or signal processing. Instead, replacements for the damaged vocal elements will be synthesised using a speech model. The latter is a component or set of components, normally including one or more neural networks, which accepts text and possibly other specifications, and delivers audible speech in a specified format – here, the speech of the required replacement or replacements. If the damage affects the entire segment, an entirely new segment is synthesized; if only parts are affected, corresponding segments will be synth­esized individually to enable later integration into the undamaged parts of the Damaged Segment, with reference to appropriate Time Labels.

The speech segments necessary for the creation of the speech model can be flexibly resourced from undamaged parts of the input segment or from other recording sources that are consistent with the original segment’s acoustic environment.

Restoration is carried out by synthesising replacements for the damaged vocal elements as follows:

The Speech Segments for Modelling – Audio Segments necessary for the creation of the Neural Network Speech Model – may be obtained from any undamaged parts of the input speech segment; however, other Audio Segments consistent with the original segment’s sound environment can also be used.

2      Reference Model

Figure 4 gives the Reference Model of the Speech Restoration System.

Figure 4 – Speech Restoration System (SRS) Reference Model

In the SRS use case, the entire Damaged Segment can be replaced by a synthesised segment, or parts within it can be synthesized to enable integration of the replaced segments.

The sequence of events in this Use Case is as follows:

3      I/O Data of AI Workflow

Table 10 gives the input and output data of Speech Restoration System.

Table 10I/O data of Audio Recording Preservation

Input Comments
Speech Segments for Modelling See Table 1.
Text List See Table 1.
Damaged List See Table 1.
Damaged Segment See Table 1.
Output Comments
Restored Speech Segment See Table 1.

4      Functions of AI Modules

The AIMs required by the Speech Restoration System Use Case are described in Table 11.

Table 11 – AI Modules of Speech Recording System

AIM Function
Speech Model Creation 1.     Receives in separate files the Audio Segments for Modelling, adequate for model creation.

2.     Creates the current Neural Network Speech Model.

3.     Sends that Neural Network Speech Model to the Speech Synthesis for Restoration.

Speech Synthesis for Restoration 1.       Receives

1.1.      The current Neural Network Speech Model.

1.2.      The NN Format information specifying the Speech Model’s NN Format.

1.3.      Damaged List as a data structure:

1.3.1.     Containing one element if Damaged Segment is damaged throughout or

1.3.2.     Representing a list in which each element specifies via Time Lab­els the start and end of a damaged section within Damaged Seg­ment.

2.       Synthesizes each Damaged Section in Damaged List.

3.       Sends the newly synthesised segments to the Speech Restoration Assembly as an ordered list.

Speech Restoration Assembly 1.     Receives the Damaged Segment.

2.     Receives the ordered list of synthetic segments.

3.     Receives Damaged List Time Labels, indicating where the synthesized segments should be inserted in left-to-right order. In case Damaged Segment as a whole was damaged, the list contains one entry.

4.     Assembles the final version of the Restored Segment.

5      I/O Data of AI Modules

Table 12 – CAE-SRS AIMs and their I/O Data

AIM Input Data Output Data
Speech Model Creation Audio Segments for Modelling Neural Network Speech Model
Speech Synthesis for Restoration Text List

NN Format

Neural Network Speech Model

Synthesised Speech
Speech Restoration Assembly Damaged Segments

Damaged List

Restored Segment


6      AIW, AIMs and JSON Metadata

Table 13 – AIMs and JSON Metadata

CAE-SRS Speech Restoration System File
CAE-SMC Speech Model Creation File
CAE-SSR Speech Synthesis for Restoration File
CAE-SRA Speech Restoration Assembly File