One of the fascinating aspects of this play is the way that Behn used the aside so much to reveal the inner thoughts and fears of her characters. This is a definite aspect of the voice of the play, as there is a very high number of such asides. Let us remember that an aside is a term given to a comment that is uttered by a character in what is known as a "stage whisper," that the other characters in stage are unable to hear. This then allows the character uttering that aside to often express honestly what they are thinking and feeling rather than the pleasing exterior that they wish to present to other characters.
Asides in this play are frequently utilised to chart the development of romantic interest between various characters. For example, when Hellena finds out that Willmore is romantically interested in Angellica, Hellena's asides communicate her love for Willmore and indicate her jealousy, therefore developing the plot whilst showing her feelings secretly to the audience alone.
Asides are also often used to indicate the intention or purpose of a character. Using the same example, Angellica remarks "His words go to the very soul of me," indicating through this aside that she is deeply impacted by her romantic feelings to Willmore rather than just playing the part (that she does so well) of courtesan.
So much of the voice of this play is therefore wrapped up in the use of the aside to reveal character's intentions and inner feelings to the audience, giving us access to the souls of various characters.