File:Noisetest.wav

400Hz with backgroung white noise. Generated with audacity.

How to generate it:

1) Generate 30 seconds of white noise, amplitude 0.1 2) Into a second track, generate 10 seconds sine wave, 100 Hz, 0.8 amplitude, starting at about 5.0 seconds along the time line. 3) Select both tracks then Mix and Render.