How to locally play a song in magnitude?

I recommend you use Coroutines and Debounce. Coroutines so you can accurately check if the player is near the part, and debounce so only play the sound once. Alternatively to coroutines, you can use the PlayerAdded() and CharacterAdded() events, so that it runs on a separate thread and works for every player without having to rescan them. Also, do you want the sound to be played once and once only, or do you want it to play whenever the player steps near the part, so that it will remain repeatable? In the finished script I made, it's repeatable and cuts whenever the player steps out of range.

Finished Script:

--Assuming the sound is named Sound and is located in StarterGui
local debounce = {}

game.Players.PlayerAdded:connect(function(player)
player.CharacterAdded:connect(function(character)
while true do
if not (player or character) then break end
if (character:FindFirstChild("Torso").Position-script.Parent.Position).magnitude<=10 then
if not debounce[player.Name] then
debounce[player.Name] = true
player.PlayerGui.Sound:Play()
end
else
debounce[player.Name] = nil
player.PlayerGui.Sound:Stop()
end
wait()
end
end)
end)