Laryngeal tension for those new to voicing is normally caused by uncoordinated respiration, phonation, and/or articulation.
Help students understand the basic processes of respiration and phonation and how tension adversely effects functional speech. Identify what tense voice feels like- this could be tense muscles that can visually be seen in the neck or experiencing fatigue after voicing in a conversation. If a student has hearing access, explore what a tense voice sounds like. With relaxation exercises, guide the student to reduce tension with simple segments, like vowels, before moving onto words, phrases, and sentences. Facilitate generalization of relaxation to more complex linguistic scenarios.
See Introduction - Laryngeal Tension for tips and a script on how to explain laryngeal tension to students in speech therapy sessions.