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. UCS Category: TEST. Duration: 00:19.
Telephone tone when the phone rings in Europe. This is a sound wave frequency of 440 Hz sinusoidal. This sound is easy to loop. UCS Category: COMTelph. Duration: 00:40.
Sound atmosphere of a cave. Created on computer, with sounds from LaSonotheque: Rain, drops of water and reverberation. Easy to loop. UCS Category: AMBUndr. Duration: 01:11.