Generally, I like movies with an ambiguous ending. In this instance I thought it was used more as a "gimmick" (being as we've been discussing gimmicks
) than a did he or didn't he. Not to be redundant with what I posted earlier, but if the writer knew anything about detectives,
Warning: Spoiler! (Click to show)
he would know a detective would never leave that property until he found the source of that noise - it would wear on him.
Detectives will work for 20 years, or however long it takes, to solve a cold case file because they just can't let it go.
I'm not nitpicking an excellent thriller, I'm just saying if the writer thought he was leaving me with an ambiguous ending, he didn't. Because this is what any good detective would have done.
That ending wouldn't have changed my opinion of the movie one iota, and I don't believe anyone would have given it a second thought. I'm okay with the ending, just don't expect me to be intrigued.