When chanting psalms, do this in a low voice, with your intellect fully attentive: do not allow any phrase to go uncomprehended. Should anything escape your understanding, begin the verse again, and repeat this as many times as necessary, until your intellect grasps what is being said. For the intellect can attend to the chanting and simultaneously can recollect God. You may learn this from everyday experience: you can meet and speak with someone and also focus your eyes on him. Similarly, you can chant psalms and focus on God through recollectedness.
~Theoliptos, Metropolitan of Philadelphia
Prayerful Life 