bell.ogg
https://pixabay.com/sound-effects/ding-small-bell-sfx-233008/

ding.ogg
https://pixabay.com/sound-effects/ding-sound-246413/

pop.ogg
https://pixabay.com/sound-effects/happy-pop-3-185288/

smooth_alert1.ogg
https://pixabay.com/sound-effects/system-notification-alert-toast-warn-274740/

smooth_alert2.ogg
https://pixabay.com/sound-effects/smooth-completed-notify-starting-alert-274739/

smooth_alert3.ogg
https://pixabay.com/sound-effects/smooth-completed-notify-274735/

smooth_alert4.ogg
https://pixabay.com/sound-effects/simple-notify-completed-process-274737/

smooth_alert5.ogg
https://pixabay.com/sound-effects/smooth-simple-notification-274738/

smooth_alert6.ogg
https://pixabay.com/sound-effects/smooth-notify-alert-toast-warn-274736/

alert1.ogg
https://pixabay.com/sound-effects/notification-alert-10-331721/

alert2.ogg
https://pixabay.com/sound-effects/level-up-3-199576/

error.ogg
https://pixabay.com/sound-effects/film-special-effects-error-011-352286/