What am I?

I never speak unless spoken to, many have heard me but none have seen me. What am I?

related riddles

I have a tongue, but cannot speak. I have a bed but cannot sleep. I have four legs but cannot walk. Yet I move as you do. What am I?

i am not alive, but i grow;i don't have lungs but i need air; i don't have a mouth,but water kills me. what am i?

Canine children. What am I?