"Dynamics," as we're using the term here, means the difference in volume between the softest part of your song and the loudest. Dynamics give your song peaks and valleys. The quiet moments make the louder moments pop, which adds excitement to a song. Moreover, a song with no dynamics can cause ear fatigue, as a non-stop barrage of loud sounds eventually exhausts the listener.
If you find that your song has no dynamics, the first thing to check is the mix. If you have a song that should be dynamic but your recorded mix isn't, check that you're not over compressing or limiting tracks or the full mix.
If you're not over compressing/limiting, it may be the arrangement that is causing your song to lack dynamics. It's a common trap to fall into, especially in heavy music where you want to sonically pummel your audience. But even then, dynamics can make your pummeling even heavier.
The most basic and powerful way to create dynamics in an arrangement is to remove instruments from specific sections of the song. You can create dynamics between verse and chorus by using fewer tracks in one than the other. Or by having a few instruments drop out right before going from one to the other. Perhaps you can write a "pre-chorus" or "chorus outro" that is beat-only, to add dynamics.
The opposite works too — if you have a sparse song that doesn't really have parts to remove, you can add parts to add dynamics. You can double guitars or add new keyboard lines to verses or choruses, or a lead solo in the bridge, and so on. However you change your arrangement, arranging for dynamics will help keep the listener engaged and make your song more textured, powerful, and interesting.
Usually abbreviated "EMI," electromagnetic interference is a disturbance in the radio frequency spectrum generated by an external source, which affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data.
Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI: automobile ignition systems, mobile phones, thunderstorms, the sun, and the Northern Lights. EMI frequently affects AM radios. It can also affect mobile phones, FM radios, and televisions. Most audio devices and audio gear that isn't properly shielded is susceptible to EMI, and if the interference is strong enough, even shielded gear is vulnerable.