1) Alternative to a tap 2) Alternative to ahem 3) Alternative to an elbow 4) Alternative to being tapped 5) Attention getter 6) Attention getting sound 7) Attention grabber 8) Attention seeker 9) Attention-getter 10) Attention-getter in a library 11) Attention-getting sound 12) Attention-getting whisper 1) In here 
(used to attract someone's attention in an unobtrusive manner.)