Using PianoSens, it is now possible to tune perfect unisons to within a fraction of a cent without matching them by ear. PianoSens is a new electronic sensor which directly isolates and measures the vibration characteristics of a single string or a combined unison set. With this new technology, we are able to dispel long held myths about tuning and piano string behavior by showing what is actually happening as strings vibrate. Resulting benefits include: 0.1 cents accuracy tuning unisons, no loss of tuning quality in a noisy environment, better false beat detection and resolution, and consistent measurement, no longer dependent on placement of a mic. Comparisons are made showing why there is currently no better way to accurately tune unisons and measure.