Abstract:

This paper presents the design and software development of a multimedia application for creating original e-learning content for viewing and processing audio files using the Matlab programming environment. The purpose of the application is to build a practical multimedia lab work that facilitates the interpretation of audio signals and their basic structural editing procedures. The application's specifications include designing an interactive user-friendly interface to facilitate student access to editing and processing tools for audio signals.

The first part of the paper presents the physical principles and properties of sounds, the noise and the behavior of sounds in the environment. The second part contains information about analogue to digital audio conversion, including capture, analogue-to-digital conversion and storage methods, as well as introduction to sound editing. The third part is reserved for the application description, both conceptually and functionally. The e-learning content application also contains an online laboratory platform designed to accommodate students with the virtual study of the available audio processing methods.

The main menu on the Home page of the application, for both the signal display area and the user interface, was implemented using the Matlab Audio Editor class. This creates a graphical interface used to edit audio signals. Users can read and write files in WAV format and apply editing options as Cut, Copy and Paste by calling Undo and Redo functions.

The main menu has two buttons, File (Open, Save, and Recent Files) and Edit (Undo, Redo, Select All, Cut, Copy, and Paste). It is possible to develop the application by adding new types of files that can be opened or saved. In the toolbar, there are buttons for uploading, viewing, playing and editing an audio file: Play, Pause, Stop, Open, Save, Zoom-In, Zoom-In Selection, Entire Signal, and Zoom-Out. For instance, the Zoom-In Selection button applies a Zoom-In operation to the selected area so that it only appears on the screen. The Entire Signal button uses a Zoom-Out operation so that the entire signal can be viewed.

The developed application does not aim to rise to the level of top commercial software, its goal being to develop students' learning and working skills with fundamental structural visualization and editing methods in audio processing.

The developed application achieves the main design requirements, the interface being simple, intuitive and easy to use, its teaching functionality consisting of visualizing, playing and editing the audio signals with basic sound processing operations. The character of the application is a highly didactic one, the purpose of designing and implementing it is to create an e-learning tool useful in the virtual study of multimedia applications integrated into the Easy-Learning online learning platform, a proprietary product of the Department of Applied Electronics and Information Engineering.

For possible further development and optimization of the application, the following topics can be addressed: support for multiple types of audio files, application of audio filters, signal analysis, or microphone recording. In conclusion, through this application, students can acquire basic knowledge and abilities in the field of audio editing, using the application in conjunction with the laboratory platform, all these being integrated into the virtual environment provided by the Easy-Learning online learning platform.

Keywords:

e-learning content, Multimedia application, Learning environment, Virtual class, On-line platform, Audio editor, Automatic-generated tools.