Testing Your Sound Card: Task Two

You will now run a couple of tests on the input section of your sound card, using three simple PD patches. The first patch sets a reference gain. The second patch measures the noise level. The third patch measures the frequency response.

To run the first patch, follow these steps:

1. Download the PureData patch 001.pd, and open it in PureData.
2. In PureData, choose Media $\rightarrow$ Audio settings...
3. Verify that the intended sound card is selected. If the sound card has several inputs, verify that the intended input is selected.
4. Start the patch: check the box Media $\rightarrow$ audio ON.
5. Load the CD player with the RealSimPLE CD.
6. If the CD player has any "bass boost" or other "sound enhancement" features, make sure that they are turned off.
7. Play the CD, track one. That track plays a continuous sine wave. You should now see a window similar to the figure below. The box frame displays the incoming signal.

   Figure 1: Correct behavior in PureData

   
8. In Volume Control (or its equivalent), find the input gain setting that allows as high a signal level as possible without clipping or visible distortion of the sine wave.

For the rest of the sound card test, do not change this setting.