Please Note: Side-by-side/simultaneous comparisons are not really productive and is not recommended for data comparison.
There are a lot of factors to consider. Let’s eliminate a few by assuming the latest version of the Inner Balance Trainer (IBT) app and emWave Pro are being compared, and that both devices are set to the same challenge level, and that the emWave2 is not being used as the sensor and (if you are using one) the phone is located in a place with good cell reception. This is important when using a Phone as poor cell connections require the Phone to continuously look for a cell tower connection which causes it to continuously output a lot of radio frequency power which can distort the pulse and subsequent HRV measurements and thus the coherence score.
It’s important to understand that when comparing two devices that each of them are analyzing and scoring the data over the past 64 seconds of HRV that has been collected which is updated every 5 seconds to the last 64 seconds of data. In order to accurately to compare, both devices have to be analyzing exactly the same data series which is very hard to accomplish outside of a laboratory setting for a couple of reasons. This is difficult with two emWave Pro's or emWave2 machines, much less a emWave Pro and an IBT.
To begin with, the time of the recordings being compared have to start at exactly the same time. Even when care is taken to start both devices at the same time, it can be difficult to achieve the same starting time as the two devices go through an auto calibration phase which can take place at different speeds, and you never really know when the recording started. In addition there can be significant difference in the strength and shape of pulse waves arriving at the two earlobes which affects the speed of calibration and the HRV recording.
For example, there can also be artifacts that are detected in the pulse wave at one ear and not the other one, due to subtle differences in the vascular system or the way the head may be turned or tilted during the recording which can cause differences in the scoring. All you need is one small artifact or disruption caught on one side/ear and not on the other to drastically skew the coherence score on one device as the artifact moves through the last 64 seconds of HRV data that is being scored. IBT does not show the artifact (redlines) on the HRV graph like the emWave Pro does, so it can be hard to spot if comparing one to the other.
Overall, a long session run side by side on both as long they are started at the same time, without artifacts from movement, coughing, talking, etc., should end up with a relatively similar overall achievement score and coherence ratios, but having them track each other exactly throughout the session is highly unlikely.