So this is a 1-Section song. It consists of one Phrase that is repeated over and over. (A Phrase is a group of different Elements that are repeated several times.) The Phrase is intricate, with 4 Elements.
Notice that each Phrase covers a lot of frequencies, including some that are very low. The first Element of each Phrase looks like a very straight line. This indicates many frequencies being sung at the same time, creating a very strong accent or even noise-like sound. Although it really has two Elements, it's so fast that it sounds to us like one Element, and so we treat it as such. The Elements in the rest of the Phrase sound staccato, as they are short, and have a much smaller pitch range. And they rise in pitch, one to the next.
All of the suggested species share this same basic structure: 1 Section with several repeated Phrases, each of which consists of a few Elements. Let’s first look at Kentucky Warbler and see if it fits.
The first thing we hear (and see) is that all of these Elements are very similar to each other. There is nothing like the variety of sound we hear in the target song. Also, the pitch is low and doesn’t cover nearly the same range, making the song sound duller and less strident.
Common Yellowthroat’s song does have a lot of variety in its Elements.
And it covers a very wide range of frequencies, although it doesn’t go nearly as low as the target song. Also, the Elements are somewhat longer, and thus sound less staccato or accented. The speed of the Phrases is also noticeably slower, in fact about half as fast. That enhances the more melodic quality of the Common Yellowthroat’s song.
Finally the pitch profile of each Phrase is a slower, more gentle, up/down form. All in all, Common Yellowthroat sounds more mellow or sing-songy than the target song, which has a very strong accent followed by a rapidly rising series of short Elements.
All of the features of the target song fit the various, variable songs of Carolina Wren. The key to identifying this species, and separating it from other species, is each Phrase’s very fast, sharp, accented Element that is then followed by a series of short Elements with either a rising or falling overall pitch profile. The fairly fast speed and wide pitch range, adds to the song’s effect.