Did you ever wonder why we use the word sound with this meaning?
No? Well luckily for you, I have!
The reason is actually pretty simple. The two most common meanings of sound came about completely independently. The most common meaning, something you hear, comes from the Old French son.
The second meaning, free from defect or injury, comes from the Old English gesund, meaning safe, in good condition. This, like most everyday English words, can be traced back to Proto-Germanic, and shares a root with Gesundheit, the German post-sneezing interjection!
Of course if you really think about it, there are two more (admittedly less common) meanings for sound. You can sound the depths of the ocean (i.e. measure them, from the Old French sonder. And there’s a sound, a narrow stretch of water, from the Old Norse sund (as these two are water-related though, there might be some slight link between them).
So, four different meanings for sound, all with quite different origins. The fact that they all look and sound the same is really just coincidence. Well, perhaps not entirely. The olders words these sounds are derived from are all fairly different, yet they all still converged on the specific spelling and sound of sound. Maybe there’s something inherently appealing the word. But there’s also the fact that, no matter how diverse a language might seem, each one is still limited a surprisingly restricted range of sounds. Imagine if the word were sond. Or sund. They sound weird, don’t they? So even though son and sund and so on are all quite different, there weren’t many options for what the English words derived from them would sound like, and so we ended up with so many words called sound.
Hopefully that’s a sound enough explanation!