There are two important aspects to an ultrasound calibration:
 :
1. Tuning. Each ultrasound transducer (crystal) reacts to a specific, unique frequency. When a sine wave of this frequency is applied, the crystal operates in a most efficient manner (highest performance with minimal effort). The tuning process alters the applied sine wave frequency in order to match the physical properties of the crystal.
2. Output power adjustment. Adjustments made during the calibration process to match the measured output and the indicated output.
The physical properties of the synthetic crystals used to generate ultrasound change over time. The rate of change is highest early in the crystal’s life and lesser as the crystal ages. Because of this characteristic, manufacturers will allow new crystals to age for a year or more before using them in their new ultrasound heads.