146
The fading light hides the look of concern which has overtaken the face of your deaf party member, but everyone notices when they stop walking, shush everyone, and crouch to put their hand on the ground.
If appropriate in your system, everyone may make a perception check against a Hard difficulty. Deaf or blind party members make the check against Tricky difficulty.
If anyone succeeds, the party has time to sprint for the treeline to the south and can continue with entry 121. Otherwise, the party is surprised and must continue with entry 120.