I don’t know how I stuck with the super annoying default notification sound for a successfully expanded Text Expander snippet for all these years, but I finally got around to finding a suitable and non-intrusive replacement.
Here’s the sound in .mp3 format, for previewing it; and the .aif sound file to download and drop into your
~/Library/Sounds/ folder (both are Dropbox links).
Notifications sounds on macOS have to be in .aif format, and it’s a bit convoluted to do it with iTunes.
I edited the original sound file, which I obtained here.
Some nice Zen bell and gong ringtones, already in the Apple .m4r ringtone format. Nice-sounding tones, and great clean recordings of the sounds. Great for meditation timing or just for unobtrusive alarms sounds. Free.