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=USUAN1100424

MacLeod's description:

Genre: Soundtrack
Length: 3:12
Instruments: Strings, Synths

A very long dark note. Use under dialog, or to kill site noise. 037
ISRC: US-UAN-11-00424
Dark, Mysterious, Somber, Suspenseful 2008