steveo_1965, unfortunately, I could hear a song a thousand times and, if I start singing it the next day, I will not be in the right key. I'll hear the song but I won't hear the key. However, if only, say, an hour goes by, and I don't hear any other music in the interim, I more than not would be in the same key. But unlike that lady violin player, I will never in a million years be able to hear any piece of music and recognize the key. I don't believe that that can be taught either. I think that's an "either you have it or you don't" kind of thing. I'll never forget reading about a guy who had perfect pitch, fell and hit his head, and then didn't have perfect pitch anymore. And he was okay in every other way, too. The man was a Broadway composer of some note, too, but I have forgotten his name. It was in the NY Times a number of years ago. I've read about that in other cases as well.
You can plan the piano on the internet to find your key from youtube if you want. Here is the link:
http://www.pianoworld.com/fun/javapiano/javapiano.htm
I don't know what keys the songs you mentioned are in. I do know that the original sheet music for This Guy's In Love With You is in Eb, but that doesn't mean that Herb Alpert was in that key of course. Wouldn't it kind of surprise you if Burt, himself, played anything in "C"? It would me.
I know that certain musicians can hear enormous differences between keys. Laura Nyro saw each key in a different color. And I've heard musicians say that they don't like a particular song in a particular key... that it doesn't sound right in, say, Bb.... but sounds great in G, for example. (I'm not talking about a singer, of course.) I, on the other hand, can discern no difference between keys when hearing a song. I'm sure that 99.9% of people can't either. If they hear, say, "Pacific Coast Highway", it wouldn't make a difference if it were in C or Ab.
That's just terrific that you can get the chords without needing the sheet music. That has bothered me more than anything over the years.
Do you know the proper chords to "Danger" by any chance? I consider that to be one of Burt's most incredible compositions… and, yet, the song seems to unknown and un-talked about anywhere. I can't imagine that Burt was anything other than totally thrilled with it after he recorded it.
Here's an example of something I love that Burt is so great at: In the song "The Balance of Nature", when the lyric goes "Day by day, we search for love, the way we all were born to do, not one by one, but two by two." I just love what Burt does there. Let's say that the song is in the key of "F". Then, on "Day by day", he switches briefly into Ab and does a I, VI, IV in Ab, but on the VI (Fm7 chord), the note of the song is a Db (“we”) – so there’s real tension there since the Db note is nowhere in the Fm7 chord, and on “love” (as in “we search for love”), he’s back to the Db note (while still in Fm7—you can really hear the tension when Burt sings that one note, too, between that note and the chord—it almost sound “off key”, but it’s not – it’s simply the work of a musical genius) and then the chord drops to the IV (Db chord) for “the way we” and then on “all” he goes back to the key of “F” with the Bb/C chord (or C11). I loved that Bridge from the moment I heard the song. And that's why.
Also, in "Finder's of Lost Loves", Burt changes the key in a most unusual place in the song and you don't even know it… it's that seamless. It's in the sheet music, too, that the key changes… it's not simply done with sharps, flats and accidentals (as the Bridge in "The Balance of Nature" is done).