Paris apartment. First floor. Closed window (some glass vibrations at low frequencies), before crossing a boulevard (acceleration and braking of vehicles). UCS Category: AMBRoom. Duration: 04:02.
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.
Several beeps of an active sonar. This is a low frequency sonar (long range but low definition). It is a sine wave of 1040 Hz frequency easy to put in loop. In reality, a military submarine usually has passive sonar, more sonar info: en.wikipedia.org/wiki/Sonar. UCS Category: BOATSub. Duration: 00:21.