1.   And his vocal heft infuses the role with dramatic gravity.

2.   Many critics predicted disaster in this role, which requires vocal heft and stamina.

3.   The South African tenor Johan Botha brought impressive vocal heft but insufficient Italianate style to the role of Enzo.

4.   This opera requires singers with vocal heft, as well as the agility to spin soft legato lines.

5.   To everything she sings, Ms. Laine brings a commanding dramatic authority that matches her vocal heft.

6.   Yet it takes most tenors years to develop the vocal heft and stamina to handle the music.