Ear training is equally important for both musicians and sound engineers. Distinguishing a frequency apart from another in an accurate way is essential for recording, mixing, and doing live sound. If musicians train on perfect pitch than audio engineers should train on perfect frequency recognition.First, being able to identify frequencies is vital to being able to mix well. Second, you'll be much better at live sound applications - especially controlling feedback - if you can identify frequencies. Also, understanding where your hearing range in way of sensitivity or attenuation of certain frequencies will help you avoid compensating for hearing issues when mixing.How To Use These TonesYou can use them to help identify and learn frequencies apart from others simply by hearing them. Quiz yourself on the frequencies you hear. You can also use them as calibration tones for live sound equipment. It's up to you what you use them for - let your imagination do the work.