There are two methods of cybernetically enhancing ears. Both options usually involve both ears as to not unbalance the users hearing.
Surgical modification involves implanting individual enhancements from the list below without replacing the entire ear. This type of modification is not outwardly noticeable.
Cyber replacement replaces the entire ear with an obvious prosthesis. This cyberear will provide perfect hearing within normal ranges and has the additional advantage that enhancements can be added costing up to 1 Essence without further essence loss. So in other words a Cybernetic replacement ear will allow a character to have ear enhancements of up to 1 essence cost while only actually paying 0.5 Essence.