0.8 Jbs2040-an audio graph of a sinusoid

Table of contents

• Preface
  • Viewing tip
    • Listings
• General background information
• Discussion and sample code
  • Three classes are unchanged
  • The class named MusicComposer07
  • The class named AudioGraphSinusoidal
    • Beginning of the class named AudioGraphSinusoidal
    • Beginning of the getMelody method
    • Controlling the output volume for each speaker
    • Miscellaneous operations
    • Map the sinusoidal function values into pulse frequencies
    • Compute the current time
    • Compute the pitch of the pulse
    • Shape the pulse amplitude from beginning to end
    • Compute the gain for the left and right speakers
    • Required audio data format
      • Monaural, channels = 1
      • Stereo, channels = 2
    • Deposit stereo audio data in the melody file
    • Controlling stereo speaker output levels
• Run the program
• Miscellaneous
• Complete program listings

Preface

This module is part of a collection titled Accessible Objected-Oriented Programming Concepts for Blind Students using Java . It explains how to create an audio graph of a sinusoid in a format that isaccessible to blind students. The program could easily be modified to create audio graphs of other functions such as parabolas, exponentials, etc.

Previous modules have created only monaural sound. This module also explains how to create stereo sound.

Viewing tip

I recommend that you open another copy of this module in a separate browser window and use the following links to easily find the listings while you are reading about them.

Listings

• Listing 1 . Beginning of the class named AudioGraphSinusoidal.
• Listing 2 . Beginning of the getMelody method.
• Listing 3 . Declare speaker volume variables.
• Listing 4 . Miscellaneous operations.
• Listing 5 . Map the sinusoidal function values into pulse frequencies.
• Listing 6 . Shape the pulse amplitude from beginning to end.
• Listing 7 . Compute the gain for the left and right speakers.
• Listing 8 . Deposit stereo audio data in the melody file.
• Listing 9 . The class named MusicComposer07.
• Listing 10 . The class named AudioGraphSinusoidal.

General background information

Previous modules have introduced you to the concept of an audio graph consisting of audio pulses that represent points on the graph of a function.Click AudioGraphSquareWave to hear an audio graph of a square wave function. Click AudioGraphSinusoidal to hear an audio graph of a sinusoidal function. (You should be able to play these audio files with any standard media player that can handle the AU file type. In case you are on the OpenStax site and youare unable to download the audio files, click the Legacy Site link at the top of this page to switch over to the same module on the Legacysite. You should be able to download the audio files from there.)

In this module, I will explain how to create the audio graph of the sinusoid. The program could easily be modified to create audio graphs of other functionssuch as parabolas, exponentials, etc.