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Circuit Description

The applet on this webpage demonstrates how to integrate the Hades simulation framework with the FreeTTS text-to-speech synthesizer. This results in a multimodal learning environment, where the interactive simulation with its animation and visualization is accompanied by context-sensitive speech output and explanations.

The circuit shown and explained here is the standard D-type latch, built from four NAND2 gates. For a textual explanation without the text-to-speech comments, please click here.

Setup

If audio output still does not work on your system, please also check the following:

• check that audio functions are enabled by your operating system.
• check volume controls and speaker/headphone cables.
• on Linux, stop all other programs that play audio (e.g. mp3 playback), then restart the Hades application or your browser (Hades applet). On many Linux systems, several incompatbile drivers (e.g. alsa/oss/artsd) are installed, and a running application will often access the sound device directly instead of accessing it via a mixer device. In such cases, other applications are denied access to the sound device.

If the applet doesn't work at all, and you are sure that Java is enabled in your browser, chances are that the applet simply did run out of memory. The default memory limit of 64 MBytes used for Java applets is a bit low when running Hades with text-to-speech output, because the speech dictionary, phoneme data, and audio sample buffer are all pretty large. Please check the applet usage page for information about increasing the memory limit; a value of 128 or 256 MBytes should be fine.