"She played a great deal better than either of the Miss Musgroves; but having no voice, no knowledge of the harp, and no fond parents to sit by and fancy themselves delighted, her performance was little thought of, only out of civility, or to refresh the others, as she was well aware." (ch.6)

The context refers to Anne's inability to sing, but how aptly the phrase "having no voice" summarises her wider situation.

Sir W and Elizabeth ignore Anne completely. Though Lady R consulted her about retrenchment she overrules Anne's preference as she did regarding the engagement and about the move to Bath. At Uppercross Anne has some limited success in persuading Mary to think more cheerfully, but mostly everyone just uses her as someone to listen to their complaints. Even then they pay little heed to what she has to say about their concerns, and have no interest at all in what Anne's personal feelings and wishes might be.

Anne having no voice looks to me very like Fanny Price's protest "I really cannot act" (MP ch.15). Fanny is unwilling to perform in the play but the phrase also describes how her circumstances deprive her of the opportunity to decide and to act for herself.