We all sing that tune, it was better back then. Well in Psalm 12:v, 1-3 they felt that things reached a high with Adam and have been fallen ever since. Good pun there, dontcha think?
1[For the choir director; on the [sheminith]; a psalm by David.]
Help, O LORD. No godly person is left. Faithful people have vanished from among Adam’s descendants! 2All people speak foolishly. They speak with flattering lips. They say one thing but mean another.
Compare this to 1 Chr 15:21
And Mattithiah, and Elipheleh, and Mikneiah, and Obededom, and Jeiel, and Azaziah, with harps on the Sheminith to excel.
It seems most probable that Sheminith denotes a certain air known as the eighth, or a certain key in which the psalm was to be sung…from Smith’s bible Dictionary.