Murmur, tweet, and whistle are examples of
anapestic meter
onomatopoeia
alliteration
personification

onomatopoeia

Explanation:

Onomatopoeia occurs when a word phonetically imitates or suggests the sound that it describes. This makes the description of a word more expressive and interesting. Some examples of these words are "oink," "meow," "roar" and "chirp." The word comes from the Greek, and it means "to make names."