+               +
                           / \             / \
                          /   \           /   \
                         /     \         /     \
     TRIANGLE          ./.......\......./.......\.
                                 \     /
                                  \   /
                                   \ /
                                    +

                              +       +       +
                             /|      /|      /|
                            / |     / |     / |
                           /  |    /  |    /  |
     SAWTOOTH            ./...|.../...|.../...|.....
                              |  /    |  /    |  /
                              | /     | /     | /
                              |/      |/      |/
                              +       +       +

                       +----+  +----+  +----+  |
                       |    |  |    |  |    |  |
                       |    |  |    |  |    |  |
                       |    |  |    |  |    |  |
     VARIABLE         .|....|..|....|..|....|..|.
     PULSE             |    |  |    |  |    |  |
                       |    |  |    |  |    |  |
                       |    |  |    |  |    |  |
                       |    +--+    +--+    +--+
                                <-->
                                PULSE WIDTH

                                   .   .       .
                          .     . .          .   .
                           .  .     .       .
     NOISE               ...........................
                             . . .        .
                                      .  . .  .
                            .                   . .



                    Figure 7-3. Sound Waveform Types