Parshas Ha'azinu opens with Hashem describing how He will address Klal Yisrael: "Listen, Shamayim, and I will speak; and let the earth hear the words of my mouth."
The Imrei Chaim ztz"l notes that this hints at how each different audience needs the message packaged differently. When talking to talmidei chachamim (as the term Shamayim suggests), one can use firm, even harsh language, as v'adabra-speak implies, as they are able to hear the rebuke and take it to heart. When speaking to simple people (as the term aretz suggests), one needs to speak softly and gently, as imrei-fi—the words of my mouth implies.
People are familiar with the idea of adapting the style to the recipient when it comes to chinuch (chanoch l'na'ar al pi darko), but the truth is that this lesson applies to all relationships. While choosing the right words is of course extremely important, the manner in which we speak them is no less so.
At Kabbalas HaTorah we find a similar concept, with the Torah given to men in a different manner from women. Bringing together these two ideas teaches us that just as each person is unique, each person needs a unique approach. There are boys and men who need a gentler approach, and girls and women who would benefit from a stronger tone. Each case should be judged individually, and hopefully we will get it right and communicate effectively with everyone we encounter.