chuckle **
chortle
laugh softly

Chance was laughing softly as he came up behind her.

She laughed softly, then turned her head to look at him.

We both laughed softly for a moment, and then I grew serious.

He laughed softly and his bright eyes took in the company.

She could hear him laughing softly as he went toward the kitchen.

She turned to the men in green, who were laughing softly among themselves.

He was close behind her and she could hear him laughing softly to himself.

The two young women looked at each other and laughed softly.

The man watching her laughed softly then turned his attention to the two young men.

All alone in the room, he laughed softly to himself.