If a person of 21 years of age speaks rapidly when excited or anxious, to the extent that their friends cannot understand them, can they do anything to remedy this? They have tried to control it without success.
You will need to develop a practice when you are not anxious. Then, when you become anxious the habits of speaking you consciously develop during your practice sessions will be strong enough to hold up under pressure. That means every day, preferably first thing in the morning.
Work with your breath to keep it full, slow and even. Sustain an “S” or hissing sound for 18 counts. Take 8 counts for each inhalation between the hissing sounds.
Then sustain vowels that resonate in both your chest and head.
Practice making crisp, clear consonants.
Read aloud for a while, using full breaths, resonant vowels and a metronome to keep your pace slow.
End your session by telling yourself that when you get excited you will breathe slowly and speak in this way.
Wear your watch or a ring on the opposite hand to remind yourself to speak slowly. Keep creating new reminders and remember it takes 30 days of continuous awareness to change a habit. After that time, it will start to be a reflex.
Also, people who speak rapidly have reasons for doing so. Try making a list of the reasons you feel there isn’t enough time to say what you have to say. Know that there is enough time. You can also seek the help of a therapist or coach to help you deal with the anxiety.