Separation of the various frequency ranges (lows, low-mids, high-mids and highs) is not an exact science. Many engineers and many various equalizers will give you a different definition and they very often overlap. For the purposes of these exercises, we will assume that the low-mids are between 250Hz and 2kHz, with the high-mids starting at 2kHz and running to just around the 6kHz mark.The fundamental frequencies of a lot of instruments lie in the low-mids (250Hz-2kHz). If you want to achieve definition, clear out the mud and really separate your mix well, you will need to get familiar with the frequencies in this range.The high-mids (2k-6k) contain complex harmonics that our ears pick up on very easily. Loudness, brightness, clarity, presence and speech intelligibility are all associated with this range, so it’s essential that we train our ears to differentiate between the various frequencies in this range.Most people usually master low-end or high end frequencies first and then start to get more attuned to what is going on in the midrange. Being able to further differentiate and fine tune between the low and high-mids can take a lot of work, but is worth it in the long run.There are two exercises folders. One contains "Guess" mode exercises (1-13) and the other one "Correct" mode exercises (14-26).Enjoy!