How can I increase the bass in audio (documentary narration, people speaking)? I have several clips where I want to increase the bass of the audio to make the voices deeper.  The audio content is people talking in normal voices; there's no music or singing.

To edit, I'm using Resolve 12.5, which has no audio plugins of its own but accepts VST plugins.  I'm also open to installing additional software if necessary.

I'm relatively new to audio editing so perhaps I'm missing something obvious, but it seems like most commercial audio plugins (such as MaxxBass) are intended for music, not speaking voices.  What can I use to increase/deepen the bass?
An article by Larry Jordan gives the following idea for using the Equalizer effect in FCPX:


  To warm a voice, here are the settings I recommend you start with:
  Men: Add 3-5 dB around 180 – 200 Hz.


There's more info in the article.  Based on this, I was able to make several improvements to the audio in Resolve.