Any way to adjust phone audio output?

[AC Question]

I sometimes have a problem hearing high range voices, such a high pitched women voices. My hearing is somewhat split, left ear hears high tones well, right ear hears low tones well. I can't switch and use my left ear for high range voices because that ear has a major hearing loss. I was looking into equalizers, but they seem to only work with earphones. Does anyone know if there is an app that will change the base and treble of the phone speaker?

Thanks.