What is 'died into the outer air'?
As the high babbling voice died into the outer air, the onlookers stirred into relief and conversation again.

Does it mean that 1) the high babbling voice could only be heard outside; or
2) the voice could neither be heard inside nor outside the bar?

(Chapter 4 - To Love and Be Wise, http://gutenberg.net.au/ebooks08/0800551h.html#ch04)

Question

What is 'died into the outer air'?
As the high babbling voice died into the outer air, the onlookers stirred into relief and conversation again.

Does it mean that 1) the high babbling voice could only be heard outside; or
                           2) the voice could neither be heard inside nor outside the bar?

(Chapter 4 - To Love and Be Wise, http://gutenberg.net.au/ebooks08/0800551h.html#ch04)

Answer

To die out means to fade out, to become weak and disappear -- in this context