A low vibration had become louder and higher: it came from behind them.

Suddenly a deafening screaming sound filled the sky, becoming louder all the time.

A whirring noise that became louder with every second - then stopped abruptly.

If anything the wind had become louder, slamming the door against a wall.

The complaints from large businesses about their soaring health care costs have become louder in recent years.

The footsteps came closer, became louder; a faint shadow appeared on the dark wall.

Though conversation had stopped, the clear tapping and scratching sounds became louder with each stride he took.

It seemed to Zoe that her voice had become louder and screakier.

In a moment there were cackles all around them, and they had become louder.

But at some point the music had become louder, waking her up.