Microsoft has applied for the above sound as a trademark for computer software and communication services. In a detailed description:
The mark consists of a sound sequence in four-four time lasting two seconds, starting with a whoosh sound on the upbeat that is held for one and three-quarters beats, after the first half beat of which a low-pitched synthesized bubble sound is struck as a quarter note and at the same time a first synthesized bowed-string sound starts on F#3 and makes a glissando up to F4 with crescendo over three beats. After the first three-quarters of a beat of the whoosh sound, a second synthesized bowed-string sound starts on C#3 and makes a glissando up to F#4 with crescendo over two and three-quarters beats. A staccato high-pitched synthesized bubble sound is struck as a quarter note on the first beat following the glissando.
I don’t recognize the sound; is this a new/prospective startup or shutdown sound?