In a 2014 listening test, 136kbps MP3 was generally rated as somewhere between "Perceptible, but not annoying" and "Imperceptible": http://listening-test.cores

In a 2014 listening test, 136kbps MP3 was generally rated as somewhere between "Perceptible, but not annoying" and "Imperceptible": http://listening-test.coresv.net/results.htm http://listening-test.coresv.net/results.htm