Unheard \Un*heard"\, a.

1. Not heard; not perceived by the ear; as, words unheard by those present. [1913 Webster]

2. Not granted an audience or a hearing; not allowed to speak; not having made a defense, or stated one's side of a question; disregarded; unheeded; as, to condem? a man unheard. [1913 Webster]

What pangs I feel, unpitied and unheard! --Dryden. [1913 Webster]

3. Not known to fame; not illustrious or celebrated; obscure. [1913 Webster]

Nor was his name unheard or unadored. --Milton. [1913 Webster]

Unheard of.
   (a) Not heard of; of which there are no tidings.
   (b) Unknown to fame; obscure. --Glanvill. [1913 Webster]

Source: The Collaborative International Dictionary of English v.0.48
 

unheard adj : not necessarily inaudible but not heard

Source: WordNet (r) 2.0
 

Unheard \Un*heard"\, a.

1. Not heard; not perceived by the ear; as, words unheard by those present.

2. Not granted an audience or a hearing; not allowed to speak; not having made a defense, or stated one's side of a question; disregarded; unheeded; as, to condem? a man unheard.

What pangs I feel, unpitied and unheard! --Dryden.

3. Not known to fame; not illustrious or celebrated; obscure.

Nor was his name unheard or unadored. --Milton.

Unheard of.
   (a) Not heard of; of which there are no tidings.
   (b) Unknown to fame; obscure. --Glanvill.

Source: Webster's Revised Unabridged Dictionary (1913)