When the voices of children are heard on the green,
And whisperings are in the dale,
The days of my youth rise fresh in my mind,
My face turns green and pale.
Then come home, my children, the sun is gone down,
The ‘whisperings’ are not explained, but these could be the trials that the children will face when they are older.  They could also potentially be the children’s subdued voices, reflecting their lack of autonomy and the oppressive control of the Nurse. In Nurse’s Song (Innocence) the children’s voices are clearly heard, indicating equality and harmony. 
 Furthermore, in ‘Nurse’s Song’ (Innocence) the children are situated on a hill and are therefore closer to God. Here they are in a dale (i.e. a valley) and so are perhaps further away from God, making them vulnerable to corruption and the Nurse’s cynicism.
Nurses Song Songs of Experience