A 1khz wave, often used as an effect for a flatline, test pattern, censorship, etc. This one more for effect (such as a movie) than a test tone. This was built with a square waveform for maximum loudness.
Exploring the medium wave frequencies. Everything here sounds creepy. Radio used was a grundig yacht boy 207 with a broken antenna, recorded on a tascam dr-05x.
Busy calm waves crashing on a beach with a hint of fizzy bubbles. Recorded in walton-on-the-naze, essex, uk. Recorded with a zoom h5 msh-6 stereo mic on a calm winter evening.