The test project is linked to my Google drive, i cannot share it on the web.
And when i export it, i have in the zip file, in the samples.json file, an array for the 8 samples for the first class “le”. And for each sample, the frequencyFrames is an array of array like in the screenshot below :
[
{
    "frequencyFrames": [
        [
            -100.85028076171875, -95.83499908447266, -88.74774169921875,
            -88.04293823242188, -82.76179504394531, -78.17805480957031,
            -78.35382080078125, -84.32926940917969, -90.46082305908203,
            -87.03742980957031, -81.06280517578125, -71.03707122802734,
            -70.29259490966797, -79.76622009277344, -84.61842346191406,
            -70.43887329101562, -65.5788803100586, -68.34820556640625

May be it is the data used inside spectrograms in the app ?