We calibrate our hearing tests with objective measurements of headphone output levels. In addition we use validation through subjective hearing tests with Mimi users. All headphones are different, and the combination of the two devices you are using for the hearing test (headphone type and smartphone type) will also influence the test results. Calibration ensures we know how to adjust for the differences between the two devices, and helps to normalize the output across devices. By using calibrated headphones, we can give you an accurate hearing test result. We are currently in the progress of calibrating headphones for Android. Because calibration needs to happen for every headphone and device combination; this can take our team quite a bit of time. We are doing our best to make sure we have more calibrated headphone/device pairings available in the future. If you have questions feel free to email us at hello@mimi.health.