Load the audio file you want to manipulate into your audio editing application of choice. The application can be anything from a basic audio editor, such as Audacity or Amadeus, to a full-blown digital audio workstation (DAW) like Logic or Pro Tools. Whatever application you use, it must have a built-in equalizer or the ability to host a third-party equalizer plug-in. The majority of audio editing applications will have a built-in equalizer, however.
Load the equalizer so it will process the audio file's signal. The procedure for doing so varies between application types. If you are working with a DAW or sequencer, it is loaded directly on the track associated with the file. If you are using a basic, single-track editor, it will be loaded universally and affect the entire signal output. Consult your application's documentation for instructions on instantiating or turning on the equalizer.
Zero all sliders on the equalizer (EQ) by placing them all at zero decibels. Equalizers generally adhere to a graph format. The vertical represents volume in decibels and the horizontal represents frequency in hertz and kilohertz. Each slider on the EQ is associated with a particular frequency range, or "band." The lowest frequencies are on the left; the highest frequencies are on the right. Some EQs have only three bands, but EQs with up to 30 are available. Generally, the more bands the EQ has, the easier it will be to reduce the level of the vocals. An EQ with only three bands will produce relatively poor results. Most software EQs have at least five bands.
Press "Play" to play back the audio file. If possible, set the audio file to loop continually until you are finished equalizing it.
Lower the sliders associated with the 85 to 155 hertz (Hz) range to manage male vocals; lower the sliders associated with the 165 to 255 Hz range to manage female vocals. Listen carefully as you manipulate the sliders. In many cases, there will be other sound information that falls within these ranges. For example, if you are trying to reduce a female vocal on a track that also prominently includes trumpet, the trumpet will also be affected. Although often unavoidable, it is sometimes possible to locate a particular band that will lower the vocals while minimally affecting accompanying sounds.
Experiment with different bands within the specified ranges for the type of vocal you are dealing with. For example, don't turn all bands within the 85 to 155 Hz range down at once to deal with a male vocal. Turn each slider associated with that range down one by one, returning them to zero before moving to the next. This helps determine which band in particular will most directly affect the vocals and help to avoid affecting accompanying voices you may want to preserve. Equalization is generally a subtle art, so it is best to move the sliders in small increments and give yourself time to hear the results before adjusting again. With time, you will eventually locate the band that needs to be reduced to lower the vocals.
Raise frequencies outside of the specified frequency ranges for each voice type. For example, raising the bass and high treble frequencies while reducing the frequencies associated with the vocals will often help to reduce the level of the vocals. This also helps to preserve the clarity of the overall sound.