Here's some ambience i recorded in 2021 when i went to surf side beach, texas for a weekend vacation with family. This was recorded from the decking of the house we were staying in. The beach was probably around 50 yards away from us, give or take a few feet. The ambience was recorded with the sennheiser ambeo smart headset (no longer made) connected to an apple iphone 8 with an app called backpack studio acting as the actual recorder.
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.