David's Tip of the Day: Different Types of Tremolo and Vibrato - Part 18, Hand Fanning

When watching players like Sonny Terry and Rice Miller on video you'll sometimes see them move their hands left to right or fan the harmonica while playing. Though they don't touch the harmonica, this rhythmic movement in front of the harmonica does alter their tone and volume in a rhythmic way. It's hard to call this a full-on tremolo due to its short duration and small tonal change, but it's cool and worthy of mention.