All sounds taken from https://freesound.org

beep_up.ogg         https://freesound.org/people/paep3nguin/sounds/388046/      Creative Commons Zero license
tiny_noize.ogg      https://freesound.org/people/kwahmah_02/sounds/254182/      Creative Commons Attriution license
retro_game.ogg      https://freesound.org/people/AlienXXX/sounds/204983/        Creative Commons Attriution license
pixel_beep.ogg      https://freesound.org/people/18hiltc/sounds/319200/         Creative Commons Attriution license
beep_positive.ogg   https://freesound.org/people/PaulMorek/sounds/330052/       Creative Commons Zero license
good_chime.ogg      https://freesound.org/people/unfa/sounds/154887/            Creative Commons Attriution license
cellular_click.ogg  https://freesound.org/people/milton./sounds/244437/         Creative Commons Zero license
bleep.ogg           https://freesound.org/people/Davidsraba/sounds/347167/      Creative Commons Zero license
mono_u.ogg          https://freesound.org/people/janhgm/sounds/237994/          Creative Commons Attriution license
plop.ogg            https://freesound.org/people/Greencouch/sounds/124903/      Creative Commons Attriution license
ether.ogg           https://freesound.org/people/Eternitys/sounds/141258/       Creative Commons Zero license
pop.ogg             https://freesound.org/people/elmasmalo1/sounds/377017/      Creative Commons Attriution license
computer_chime.ogg  https://freesound.org/people/TheAtomicBrain/sounds/351879/  Creative Commons Zero license 
beep_a.ogg          https://freesound.org/people/jobro/sounds/33784/            Creative Commons Attriution license
