The Yaka typically turn to a ngoombu (diviner) when seeking identification of an illness or misfortune. It is the ngoombu's responsibility to identify the cause of the aliment and recommend a remedy, without prior knowledge of the client or his/her situation. A n'koku ngoombu slit drum (also called n-kookwa ngoombu in some sources; meaning 'diviner slit drum') is an object that forms part of the divination ensemble. While divination is in progress, the ngoombu taps the drum with a small gong attached to it. It is believed that the sounds made are used to call on spiritual powers and also represent words from the mouth of the diviner and in turn he must translate the sounds to reveal the cause of the misfortune inflicted upon the client.
The drum is also used in a number of different ways: