He opened the door and sauntered into the living room, humming under his breath.

He was humming to himself under his breath and seemed so deep in thought that Mark felt the moment unsuitable for an interview.

He began to hum under his breath: He was happy.

Someone was humming under her breath, high and sweet.

He could hear her humming under her breath as she worked.

She became absorbed in this task and soon found herself humming under her breath.

You walk in silence, although Diamond seems to be humming under his breath.

To his side, Jenny began to hum under her breath.

When he returned, humming a little under his breath, she knew he'd hit paydirt of some kind.

Then he walked twice up and down the room, humming tonelessly under his breath.