Deëscalation tip #57: Follow this advice: Don't follow advice without due diligence.

Follow this advice: Don't follow advice without due diligence. 

This is certainly true with deëscalation. 

One source will tell you to approach an escalated person and match their intensity and volume and then slowly dial it down. 

Experience plus many other sources will dictate otherwise. Emergency first response to escalation: 

• remain calm and composed without seeming smug
• talk in a soto voce, quiet and few words
• use a greeting that feels respectful, neither inappropriately familiar nor coldly impassive
• use affirming body language, sometimes including a caring expression, sometimes a soft smile, sometimes nodding (but not rote and repetitive, nor overly emphatic)
• without simply repeating them, offer them a brief summation of even one or two points that you heard from the escalated person, but do so in a way that invites them to correct any misinterpretation or misrepresentation you've made
• once you feel you've heard their points and they have clarified them, begin your inquiry toward the reasons, starting with Why do you want that? or Why do you feel that way?

Indeed, your body language is far more important in many ways than your spoken words. All you have is your body language when someone is taking up the entire spoken environment, ventilating with a determination you should not interrupt with your own verbosity. 

Current neuroscience is telling us that it is more likely that we naturally emulate angry behavior via mirror neurons than to reflexively engage in mirror neuron-driven emulation of calm. This means your calm affect and engagement may need a longer application to effectively draw down the rage than rage takes to stimulate emulation. In short, your deëscalation skills take far more discipline.

The overarching message you are conveying is respect. You listen; you don't judge. You respect the emotional content of their behavior by acknowledging that it's intense and you hope they will help you understand. Speak softly. That's your big schtick.