Definition of "tsking"

[…] the lights suddenly went out, plunging the entire monastery into damp darkness. A momentary silence followed, and then I heard tiny gasps and frightened tskings, scuffling footsteps, the rustling of rain slickers, and the annoyed mumbling of the priest.

2004, Rosemary Mahoney, The Singular Pilgrim: Travels on Sacred Ground, page 83