https://www.theverge.com/2018/7/23/17603596/amazon-echo-speakers-equalizer

Today, Amazon announced a new equalizer (EQ) feature for the Echo that will allow you to adjust the way your music sounds when it’s played.

As part of the new feature, you will be able to adjust the bass, midrange, and treble individually, within a range of plus or minus 6dB. After it rolls out, you’ll be able to adjust the EQ via voice commands for Alexa or manually through the Alexa app or on-screen controls with the Echo Show or Echo Spot. There are a variety of ways you can ask Alexa to change the EQ, like “Alexa, turn up the bass,” “Alexa, set treble to maximum,” and “Alexa, reset equalizer.”