Sing a few songs to your baby that explore changes in volume, a good example is:
I hear raindrops
Sing the first verse quietly and say the word ‘thunder’ in a louder voice in the second verse. When you first sing this, only say the word thunder in a slightly louder voice, you don’t want to alarm your baby. As they get used to the song, the loudness can be increased.
I hear raindrops; I hear raindrops from the sky, from the sky
(Tap fingers to imitate raindrops moving them towards your baby’s head)
Patter on my head, patter on my head
(Tap fingers on your baby’s head)
Rub them dry, rub them dry.
(Rub palm of hand over head)
I hear thunder; I hear thunder in the sky, in the sky
(Clap your hands together on the word thunder and say the word thunder slightly more loudly)
Tap on my cheeks, tap on my cheeks
(Tap fingers on your baby’s cheeks)
Now it’s gone, now it’s gone.
(Rub palm of hand over head)