In the voice, passaggio (Italian for 'passage') describes the shift in resonance (see vocal resonance) between one part of the voice and the next, e.g. between chest voice and head voice. The region of the passaggio is where muscular adjustment and/or resonance activity make it especially difficult to negotiate a balance between airflow and vocal fold adjustment. Men have about three passage areas in their range, while women can have as many as five or six. Primo passaggio, "the first passage", is the first register change perceived in a voice; the second is secondo passaggio.