I metered my raw data usage while streaming on various qualities on both my
Wi-Fi connection and my 4G connection to see if there was a difference in
the quality it pulled/streamed. Wi-Fi and 4G pulled Extreme quality at all
times as long as I had a connection (Above 190KBs audio quality).
>From there I tested from the same device with 4G toggled off, using 3G
instead and finally saw a drop in quality to what can be assumed as High
quality (below 190KBs but above 120).
Beyond and below that is Normal quality where it's between 90-140KBs. (You
notice static and a 'crunch' to the music).
Most phones have a data metering service in the application>data usage
section on Android so I was able to make easy notes as to the total data
pulled on WiFi and off.