Typically, between any two languages, many words (and expressions for that matter) don't have a direct equivalent between the two languages (even if the two are of the same language family).
This said, in Arabic, the word صوت notes sound in general (as well as voice). On the other hand, there is another specific word for "noise" in Arabic and that is ضوضاء (DhawDhaa2). There are even a number of other words.
Referring back to the situation when someone hears something unfamiliar, I think it is a cultural thing where English speakers would call unfamiliar sound as (noise) maybe, while in Arabic we would say (sound), i.e. صوت. The word for noise in Arabic ضوضاء is typically kept for loud continuous noise, high volume sounds, or even technical noise (specially grains in photos for example).
TJ your point on how loud the noise is interesting...if something is noisy that definitely means loud....but we do use noise for quiet sounds that are unexpected/unwanted..." What's that noise?".... and yes we use noise for interference (or electrical devices) as well... but talk about sound in science "sound waves"....
We have also other words for the noise in Arabic, like جَلَبَة (jalabah) and typically it is used for (i'd say) medium level noise of moving objects or steps and maybe shouting people somehow, or things falling on the floor. I think there are others as well but i can't remember them well right now
Yeah I've never really thought about the difference between noise and sound.... noise i would say is an unwanted sound...so there is normally something negative about noise (i say normally because there are always some people you like noise!). If the neighbours are drilling...we would call that noise...but if the birds are singing we might say " "what a lovely sound".