The neighbor's poor baby

The neighbors' baby cries. A lot. And they are obviously of the "let them cry it out" philosophy. I even knocked on their door once at around 11:30 PM to "see if everything was OK" and tell them that their baby's crying was waking up my son, and they explained they were "Ferberizing" the baby. Ugh. This has been going on for several months now, so it's obviously not working, if their goal was to teach the baby not to cry. The poor thing cries off and on much of the day and a lot at night, too. The cries vary, from screaming disturbed cries to repetitive rhythmic cries. He woke me up this morning with his cries at around 6:30 am, what with everyone's windows open from the heat. He's cried on and off this morning. It was so nice and peaceful when they were out of town last week, I had forgotten how obnoxious the crying was. I don't know what else to say except I feel bad for him.