Question

Is this an example of assonance: How now, brown cow?

Answer 1

Yes

Explanation:

Let's first talk assonance - it's the use of the same vowel sound with words close together to create noticeable repetition (there needn't be rhyming, merely repetition).

http://literarydevices.net/assonance/

Does How now, brown cow meet the definition? There is a repeated vowel - "ow" - and the words follow each other, so there is no question the repetition is noticeable.

And so yes, this is an example of assonance.