It is the "default" setting of the human voice. When we don't have the words, or when words are too heavy to carry the weight of a moment, we retreat into the "La." The Shield and the Song
Phonetically, "La" is effortless. It requires a simple flick of the tongue against the alveolar ridge—the roof of the mouth just behind the teeth. Because it is so physically easy to produce, it is often among the first sounds a child utters and the last sound a humming adult clings to when a melody remains but the lyrics have faded. LaLaLa
When we sing "LaLaLa," we aren't just filling space; we are celebrating the fact that we are alive, breathing, and capable of making sound. It is the sound of the soul taking a deep breath and letting it out as music. It is the "default" setting of the human voice