Final answer:
Emily Dickinson employs assonance and alteration in her poem to create sonic effects.
Step-by-step explanation:
The sound device(s) employed in the phrase, 'too cool for corn,' and the line, 'But when a boy and barefoot,' are assonance and alteration.
Assonance refers to the repetition of vowel sounds in nearby words. In the phrase, 'too cool for corn,' the repetition of the long 'o' sound in 'cool' and 'corn' is an example of assonance.
Alteration, also known as consonance, is the repetition of consonant sounds in nearby words. In the line, 'But when a boy and barefoot,' the repetition of the 'b' sound in 'boy' and 'barefoot' is an example of alteration.
Learn more about Sound devices in poetry