An assessment of a client's vocal cords requires indirect visualization of the larynx. Which instruction should the nurse give the client to facilitate this procedure?

Indirect laryngoscopy is done to assess the function of the vocal cords or obtain tissue for biopsy. Observations are made during rest and phonation by using a laryngeal mirror, head mirror, and light source. The client is placed in an upright position to facilitate passage of the laryngeal mirror into the mouth and is instructed to breathe normally. Swallowing cannot be done with the mirror in place. The procedure takes longer than the time the client would be able to hold the breath, and this action is ineffective anyway. The tongue cannot be moved back because it would occlude the airway.