Possible Clues:

• You might get a blow from the pair of them, by the sound of it
• 'Herzog' author
• To start with its ring is loud
• Cry as of bull
• Deep roar as of bull
• Loud deep sound as by bull
• Carrying voice of a writer
• 'We shall be at Hebron before they - their eyelids' (Disraeli, Tancred)
• Buy-one-get-one-free item?
• "Humboldt's Gift" author Saul