Default Voice Assistants: Alice / Alpha Question

Hi all,

i have these two Voice Assistant's on my G2, i like them booth, but there is a major problem for me,
when i'am @ home i want-'t that Alice or Alpha running in the Background and listen for some commands,
but when they run in listen mode booth of them are produce a very annoying Sound while listening

how can i turn off this sound?

booth apps have a setting for this, booth turned off with no effect .....

thx for help
Device: LG G2 D802 EUR XX
Rom/Kernel: Optimus LG G3 Port 1.1 / Dorimanx 6.0
Baseband: KK_Baseband_D802_AUT_20D
Provider: 1&1 (Vodafone)