A right to free speech is separate from, and in conflict with, a right to be heard

There has been some discussion of late about what free speech really means, with some saying that unless it comes with a right to be heard, speech isn't truly free, and others like myself saying that speech is free so long as the government doesn't do anything to limit it. I hope this logic exercise will explain why free speech and a right to be heard are separate rights, and that if they are both considered rights, would be in direct conflict with each other.

Adam and Betty are standing next to each other, giving their opposing views on the one topic, talking at the same time and with the same volume. Chuck and Diane are also standing next to each other, across from Adam and Betty. Adam wants to be heard by Chuck, and Betty by Diane, but neither can be heard because the two speakers are making each other unintelligible.

In a world where free speech is a right, this is an acceptable situation. No one is preventing Adam or Betty from saying anything, the words are still exiting their mouths in a public space. But what happens if we include a right to be heard?

Adam wants to be heard by Chuck, so for that to happen, Betty would have to stop talking, or become quieter in comparison, and vice versa if Betty wants to be heard by Diane. The only way for either Adam or Betty to exercise a right to be heard, is for one or the other's right to speech to be infringed.

Canadian constitutional law does allow for the infringement of rights when justifiable, but what justification is there to infringe on Adam or Betty's right to speak in this case?