Because of its title and first-person point of view, “song of myself” is often perceived as autobiographical. when reading a poem, should readers assume that the author is the speaker?

No; poems are products of imagination and express beliefs that may not be the writer's, so that readers should not assume that the author is the speaker of the poem.

"Song of Myself" is a poem by Walt Whitman (1819-1892) that appears in his work Leaves of Grass. The poem is written in free verse style.

In "Song of Myself," Whitman highlights an all-powerful "I" which is the narrator, and who should not be confused with the person of the historical Walt Whitman.

the two answers are

get thee back into the tempest and the night's plutonian shore

on the pallid bust of pallas just above my chamber door