Double-click the desktop icon to launch the digital audio workstation with which the vocals were recorded, for example Mixcraft, Audacity or Pro Tools.
Open the "File" menu and launch the relevant session.
Click on the lead vocal to highlight it. This assigns subsequent commands to that audio file, as opposed to the entire mix.
Click "Play" so you can hear you changes in real time.
Open the "Effects" menu and select "Compressor." This effect minimizes the gap between the quietest and loudest part of a piece of audio, effectively "squashing" the sound wave. By doing so, you remove any volume spikes. Once compressed, you can boost the overall volume of the vocal so the quietest part is more audible, without the louder parts peaking, or dominating the mix.
Adjust the "Threshold" dial so the threshold line sits half way between the top of the highest volume peak and the "Average Volume" line. This means only sounds significantly over the average volume are compressed.
Open the "Effects" menu again and select "Reverb." This effect adds ambiance to a sound, creating similar results to rapping in a cave.
Set the "Depth" and "Time" settings low for a subtle, yet effective modification. The reverb will create the illusion of space and the sustained ambiance of the rap vocal will lift it in the mix.
Open the "Mixer" interface. The process for doing this varies according to which digital audio workstation you use, but typically you click the "Mixer" tab on the bottom or top of the interface.
Move the virtual "Gain" slider for the vocals up as far as it will go before the red meter warning light begins to flash. This light flashes when the signal is too high and will cause audio distortion. Find the loudest level before distortion.
Adjust the "Hi" and "Mid" dials in the equalizer section of the channel strip to around 80 per cent. These control the high and mid-range frequencies. By boosting these, you strengthen the top part of the vocal audio, giving it more "bite" and presence. This will help the vocals stick out and cut through even an extremely dense backing mix.