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=USUAN1100431

MacLeod's description:

Genre: Classical
Length: 1:32
Instruments: Basses, Cellos, Oboe

Long broad notes with a solo oboe. 036
ISRC: US-UAN-11-00431
Dark, Somber, Unnerving 2008