Music by Kevin MacLeod. Available under the Creative Commons Attribution 3.0 Unported license. Download link: https://incompetech.com/music/royalty-free/index.html?isrc=USUAN1100073

MacLeod's description:

Genre: Soundtrack
Length: 0:16

If the title doesn't say it... The sound was accomplished by recording a piano, doubling the recording and pitching one down almost an octave while pitching the other up almost an octave. 034
ISRC: US-UAN-11-00073
Dark, Bouncy, Mysterious 2005