The song has been said to resemble that of the chestnut-sided warbler, but the two are really quite distinct; the song of the latter does not end in a trill or in chipperings. It does, however, more closely resemble the song of the Tennessee warbler. Dr. Roberts (1936) heard the two singing at the same time and noted this difference: "The Nashville's song is an utterance of rather greater volume than that of the Tennessee and differs, also, in the fact that it has a short, rapidly weakening trill or slide, following a rather long and deliberate prelude of four or five notes; while the Tennessee has a brief prelude with a long finishing trill, increasing in loudness and intensity to an abrupt ending." Aretas A. Saunders contributes the following study of the song: "The territory song of the Nashville warbler is in two parts, the first a series of 2-note phrases, and the second a series of rapid notes, commonly lower in pitch and just twice as fast as the notes of the first part; _pa tipa tipa tipa tipa tititititititit_. In 26 of my 29 records the second part of the song is lower than the first. In the other three it is higher. "The pitch of songs varies from G´´´ to F sharp´´´´, or five and a half tones. Single songs rarely vary more than one and a half or two tones. They are from 1-2/5 to 2 seconds in length. The quality is rather musical, and some individuals have almost as sweet a tone as the yellow warbler. In my experience field students often confuse the songs of these two species. "The nesting song may be heard commonly on the breeding grounds. I have several records from the Adirondacks. This song is in three or four parts, each part of three or four notes, and a little lower in pitch than the preceeding part. Two-note phrases are not commonly heard in the nesting song." Francis H. Allen's rendering of the song is not very different from the first one of Mr. Saunders', though he noted some variation, and mentions in his notes an aberrant song, which "doubled the common song, which in this case had a first part consisting of only a single phrase, thus; _chip-ee-_(trill) _chip-ee-_(trill)." _Field marks._--The gray head, white eye ring, olive-green back, bright yellow under parts, and the absence of wing bars, with no white in the tail, are the distinguishing marks of the eastern Nashville warbler. The Connecticut warbler has a white eye ring but it has a gray throat, whereas the Nashville is bright yellow from chin to abdomen. The chestnut crown patch is not very conspicuous in the male and is less so, or entirely lacking, in the female; the female is duller yellow below and browner above than the male.