The present invention relates to engineered heteromultimeric proteins, and more specifically, to methods for producing and purifying heterodimeric proteins, such as bispecific antibodies and. Methods for producing and purifying such engineered heterodimeric proteins and their use in diagnostics and therapeutics are also provided. The present invention also relates to a humanized antibody that specifically binds human TrkB and methods for producing and using the antibody to, inter alia, treat a hearing loss disorder.