Bugbears are silent?

Listening at Doors, from the DMG

Race Of Listener Chance Of Hearing Noise

Dwarf 2 in 20 (10%)

Elf 3 in 20 (15%)

Gnome 4 in 20 (20%)

Half-Elf 2 in 20 (10%)

Halfling 3 in 20 (15%)

Half-Orc 3 in 20 (15%)

Human 2 in 20 (10%)

Once you add in the racial modifiers, these are the same percentages as a 1st or 2nd level thief.