Small brook, blackbird, fly, birds, 2 different sounds of the brook (on the left, a deeper "meander" and on the right another shallower one, so I put myself in the middle!). Forest of Signy-l'Abbaye (Ardennes). Duration: 05:00.
Two-tone siren of the French Gendarmerie. Doppler-Fizeau effect of a passage from left to right, made by computer. No engine noise, it's up to you to choose the noise of your vehicle according to your project. Duration: 00:20.
Pink noise or 1/ƒ noise (sometimes also called flicker noise) is a signal or process with a frequency spectrum such that the power spectral density (energy or power per Hz) is inversely proportional to the frequency: en.wikipedia.org/wiki/Pink_noise. Duration: 00:19.