Black-chinned Sparrows (Spizella atrogularis) can be identified by the "bouncing ball" finish to their songs. Here are two examples, sung alternately by the same bird who was in the Scrub Oak/Chaparral near Wilhoit, Arizona, 7/20/98.
These are Brewer's Sparrows (Spizella breweri) singing their hyped-up Spring songs. These guys are the winners of the "fast talking sparrow" award in these parts! The songs are sung at low volume, however, so recording them is a challenge.
Chipping Sparrows (Spizella passerina) gather in small flocks and sing these wispy songs in the Springtime. Like the Brewer's, above, they sing very quickly and very quietly, making it difficult to pinpoint just which individual is singing.