Voice/vocals are really hard to hear on my iPod I have an iPod Touch (4gen), and I listen to a lot of vocal music and spoken-word audio.

Sometime in the past week or so, voice became really hard to hear.  When I play music, it sounds like it's been turned into an instrumental.  When I play spoken voice, it sounds like the Peanuts teacher.

If I turn up the volume to the max, I can hear the voices fine, but then the low-frequency music is overwhelming, so that's not an option.

Is there some equalizer setting (I didn't think the iPod Touch had these but I could be wrong) that I could have screwed up to make this happen?

UPDATE:

I'm suspecting a hardware issue.  I've not mistreated it, but I've found that with some headphones, if I rotate the plug in just the right way, the vocals come back just fine.  I'm not sure how an audio jack can be plugged in and receive non-vocal sound but not vocal sound, but that's what it sounds like.  I'll take it by an Apple Store and see if they can do anything.  The audio jack is certainly the weakest part of the iPod these days, so it's not entirely surprising that it's the first thing to go.
There is in fact an equalizer setting on the iPod touch.  Go to Settings -> Music -> EQ to get a list of all of the different equalizer settings.  The best choices for you are probably "Off", "Spoken Word," or "Vocal Booster."  If your problem continues, feel free to leave me a comment.