Compression is used for dynamic vocal performances. Dynamic means shifts in loudness to represent the performance of the song. Using compression, vocal engineers can capture a dynamic performance without the audience reaching for their volume knobs every ten seconds. One of the main settings of compression is ratio. The ratio setting determines how much gain reduction is applied to the vocals. For instance, a ratio of 1:1 means no difference, while 3:1 means for every 3 decibel above the threshold there is only a 1 decibel increase.
Limiting sets a threshold the signal cannot surpass. There are two different types of limiting characteristics: hard limiting and soft limiting. Hard limiting does nothing until the vocal track reaches the threshold set by the user. Once the threshold has been surpassed, the user-set gain reduction is applied to the vocals immediately, causing a sharp angle in the slope of vocals. Soft limiting differs from hard limiting in that it slowly applies gain reduction at lower ratios while the vocal signal comes into range of your threshold. Once it surpasses the threshold the set amount of gain reduction is applied, creating a more natural curve.
Reverb is used to compliment the voice of the singer. It does not, however, act as a separate effect, but is meant to blend with the vocals. Voice tracks require low diffusion settings to avoid the effect overpowering the vocals. Adding a high decay to the reverb gives the vocals a crisp sound by adding slight echoes to the "s" sounds prominent in the upper kilohertz range.
Vocal overdubbing is done to give vocals a deeper, more harmonious sound. Overdubbing is effective for singers who record without backup singers, as they can simply go around their recorded mix with a second track providing the back up vocals. Overdubbing gives a stronger sound to the vocal performance, particularly over words which need emphasizing.