

audio frequency spectrum
In order to optimize loudness, audio signals must be in good sonic balance. Too much power in the low-end of the sound spectrum wastes much of the sound energy on frequencies that don't project over low fidelity sound systems. The result will be audio playing back at a perceived lower volume. Conversely, too much energy in the high-end will make the sound thin and empty. Getting the sonic balance right is essential.
audio volume level
To get your music as loud as other professional projects, it must be optimized for loudness. This complicated process performed by the Sound Engineer, allows the audio to be as loud as possible without damaging sound systems during playback. Limiting is a part of loudness mastering. Making the audio safe to play on all systems is crucial, especially if your music is going to be played back over radio stations.
audio fine tuning
Every recording and mix is uniquely different. Even if they are recorded back to back on the same system, on the same day, by the very same musicians. This can make significant differences to the perceived loudness of a group of songs played in succession. Audio mastering can equalize each song so that they are consistent in loudness and sonic balance, thus not disturbing the listening experience.