Your voice

When preparing to pass a slower person (bicyclist, skater, or pedestrian), it is normal to say or shout "On your left", then pass to their left. However, they might not understand you. Wait until they look back, and you think they have understood the situation, then pass to their left.

No matter how you signal, you must be alert. People might dart into your path, in spite of your signaling.

If you approach a horse and rider from behind, use your voice instead of a bell or horn. The horse is accustomed to hearing human voices, but an artificial noise could startle it.