High frequency signal:
-
Electronic signal, energy buildup
-
High frequency squeak
-
Geiger counter
-
Welcome, Morse code
-
Radio Setup
-
High frequency pulsating electronic signal
-
SOS signal transmission, Morse code
-
Police radio
-
White noise
-
Morse code transmission
-
SOS signal reception, Morse code
-
Horrifying throbbing low-frequency rumble
★★★★★