Final answer:
The voice of the fugitive slave, calling for justice, is the loudest in 'Song of Myself' by Walt Whitman.
Step-by-step explanation:
In Walt Whitman's 'Song of Myself,' the loudest voice among the many recorded is the voice of the fugitive slave, calling for justice. This is evident in the lines that describe the voices of the interminable generation of prisoners and slaves, and the sorrow expressed through their songs. The voice of the fugitive slave represents the deep emotions and the struggle for freedom, making it the loudest voice in the poem.