In the poem "Success is counted sweetest" in the third stanza, what is the ear "forbidden" to hear?

The last stanza of this excellent poem by Emily Dickinson
seals her argument that success can only be savoured and understood most by those who,
ironically, do not succeed, by giving us an example to prove her point. This example
refers to a defeated and dying soldier on a battlefield, who as he lays there, awaiting
death and contemplating his failure to succeed, is described as hearing the sounds of
victory that the winning army make:

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As he
defeated--dying--

On whose forbidden
ear

The distant strains of
triumph

Burst agonised and
clear!

Thus the "ear" relates
to the ear of this dying soldier, who, Dickinson argues, can "tell the definition" of
success much better than any of the victorious army. To understand success, Emily
Dickinson seems to be saying, you have to not achieve it, because if you are successful
you take it for granted.