The sound of footsteps, whirring baggage carousels, general hustle and bustle – and yet you are still led out of the terminal quickly and safely in an emergency.

Lounge music, jazz, classical – yet still effortlessly hear every order loud and clear.

Pounding feet, puffing and panting, the clanging of weights – yet still hear the trainer’s instructions for the next exercise.

The clearing of throats, heckling, clanking bottles – yet still manage the debate confidently and authoritatively.