This is answer 5C in "BizQuiz: Working with overeager horse owners."
5C. Really wrong. It doesn't work when speaking to foreigners, and it doesn't work for equine clients. If clients didn't understand you, there are better ways than volume modulation to improve your communication style.
One reason a client may not absorb what you've said is that he or she has a different communication style. Listen to your client's word choice, and pay attention to his or her nonverbal communication-then try to match your communication style. For example, if your client uses lots of hand gestures, he or she's likely visual and will respond well to diagrams and demonstrations. With practice, you'll get better at identifying people with different communication styles.
Another strategy: Direct your client to someone else within your organization. Maybe a technician or assistant could present the information to the client in a different way.
If your client's compliance falls short even after you've made your recommendation clear, consider other underlying causes. Has your client had a bad experience with the procedure you're recommending? Or is your client pressed for time or money? Again, your communication skills are paramount here.