A soft upward blip that opens like a bubble, then a short bright note. Use it for chat messages, badge counts, toasts and anything that wants attention without sounding like an alarm.
sine sliding 400 Hz -> 900 Hz over 15 ms (the "blip") then sine 1568 Hz (G6), 110 ms, 12 ms after the blip small noise tick at the start, 4 ms band-pass 3 kHz envelope: 1.5 ms attack, 110 ms decay on the G6