| The line between rock musicians and seven-year-olds is often imperceptible. |
| Two were eating out of the bowls that refilled so slowly that it was imperceptible, and two were eating out of regular bowls. |
| On these repeat visits, subtle qualities gradually reveal themselves which were initially almost imperceptible. |
| In addition, fluid flows, airflows, strain forces, and acoustical waves that were previously imperceptible might now be detected. |
| He noticed a beginning, almost imperceptible touch of red around her eyes, a stoop to her shoulders that had not been there before. |
| I could hear the call going along the line, but then at the final moment, instead of ringing, there was a strange, almost imperceptible hiccup. |
