My closest approximation to the call of Audubon's Warbler "chee chee chee chee chew chew chew." The notes are cleaner and maybe a bit higher pitched than Myrtle Warbler. Myrtle & Audubon Warblers spend a significant amout of time together throughout the year, at least here on the West Coast. They can probably imitate each other. It may not be useful to put a lot of time into separating these two. The call note is a flat "tat"
The difference between Audubon's and Myrtle Warblers is subtle even on the sonogram. "Zee zee zee zee zool zool zool." The Myrtle song is buzzier and a bit lower. The call note is a bit fuzzier that Audubon, but the separation is probably not great enough for regular reliable differentiation.
Townsend's Warbler the second most common wintering warbler in the Pacific Northwest. Its song, at least to my ear is most similar to Black-throated-gray Warbler, but it higher with a buzzy middle piece that is quite distinctive, "tsee tsee tsee tsee ZEE zurt." The breeding range for Townsend's Warbler is the north Cascades and the Olympic Range. They would not be expected in most of the Coast Range. The call note is a high, thin "tip."
Black-throated-gray Warbler is the only breeding Dendroica warbler likely to be encountered in at lower elevations in the Pacific Northwest. Its song is substantially different from other lowland mixed or desciduous forest warblers. Once migration is over and all the Townsend's Warblers are gone, this call becomes easy. I would describe the call as "jerzy jerzy jerzy TSEE tsert." The call note is a "tip" lower sounding than Townsend's.
Hermit Warblers breed in higher elevation coniferous forests of the Coast and Cascade Ranges. The call is described by Peterson as "sweeter sweeter sweeter chup chup." I hear "zooly zooly zooly zur dip." The call note is similar to Black-throated-gray Warbler, perhaps a bit flatter.
Nashville Warbler is most commonly found in drier scrubby habitats. The song is a consistant "tsee-tsur tsee-tsur tsee-tsur tsee-tsur," along a regular set of frequencies. The song may or may not end in a steady trill.
MacGillivray's Warbler is most commonly found in well watered scrubby habitat. It has a distinctive, emphatic "tack" call note and the has been described as having the cadence of the "da-da-dump da-da-dump da-da-dump-dump-dump" part of the William Tell Overture. I think this is only approximately true. I hear "tsee tsee tsee tsur tsur tsur" or "tseetle tseetle tseetle tsur tsur tsur."
Yellow Warblers can be found in desciduous willow wetlands. In some places this species is ubiquitous in others it is declining. The song is a very high "tsee tsee tsee soo soo-soosoosoosoo." The call note is high "SPIT."
Orange-crowned Warbler has one of those impossible to write songs that is best described as a trill, dropping off at the end. The sonogram shows a tight batch of sounds lowering in frequency at the end. The call note "sstick." Orange-crowned Warblers regularly over-winter in black-berry thickets, especially along the coast.
Wilson's Warbler breeds is descidous woodlands and is often associated with Alder woodlands, preferring the middle story. Wilson's Warblers are also the most common breeders residential areas where appropriate habitat is available. The song is a "tcha tcha tcha-tchachachacha" of fairly regular frequency, but speeding up at the end. The call note similar to Orange-crowned Warbler, but crisper.
Common Yellowthroat has the most memorable song, "witchity witchity witchty witchity" and the most easily recognized call note, "chup." The Common Yellowthroat also does a raspy rattle that is distinctive. Common Yellowthroats prefer wetland scrub, willows and Scotchbroom. The males have a cool little fluttery display flight that often accompanies the "witchity" call.
The sonogram pretty much speaks for itself with chats. They have an ecclectic series of whistles, rattles and coughs which they produce day and night. Chats are associated with the dense vegetation along riparian zones. They are down right rare along the coast, but become increasingly regular as one works east over the Cascades into the Great Basin.