IIf you get really close to a singing Slaty-backed Nightingale Thrush, the song can lose some of the ethereal quality that it gains from reverberation and natural acoustics. This example was recorded for only a few meters away - you'll see what I mean.
Hermit Thrushes (Catharus guttatus) sing one of the most beautiful songs in North America in the springtime. This recording was made on Mingus Mountain, near Jerome, Arizona, 5/31/99
The call of this bird is nothing like the song, in fact it a bit harsh - rather like a Spotted Towhee's mew (that's a warbling vireo in the background). You'll notice that this bird's song is made up of similar short phrases, raised and lowered in pitch with each iteration.