Jasper (in Washington state), to help you, check out some western USA warbler sonograms:
Using them in combination with audio recording of each species’ song may be a good strategy to successfully “reading” corresponding sonogram for a given species.
Two sound-alike western species sonograms — the Hermit and Black-throated Gray Warbler — are shown here. Where their nesting ranges overlap (e.g., Mendocina County in northern California, among other places), you can sometimes hear them singing in the same forest.
In addition to these sonograms, my solution is to listen carefully when afield. Both species appear to possess dialects that may vary be region. But, for what it’s worth,
my description of the Hermit’s song is that it’s more wheezy and less articulate/focused than the Black-throated Gray’s.
At http://www.pacifier.com/~mpatters/archive/warbler/sonoguide.html, the author has his own description of how to distinguish each warbler’s song.
In addition: Donald E. Kroodsma’s book “The Singing Life of Birds” provides clues on how to “read” a sonogram as does his chapter “Vocal Behavior in the Cornell Lab of Ornithology produced “Home Study Course” that you can purchase (See:
Ultimately, it’s my humble opinion that getting out as often as possible during the breeding season and listening is the best remedy. Simply: What You Sow, Yee Shall Reap by listening carefully each time you’re afield where the warblers sing.