Try the following free resources and see if it helps.
Mantras Explained - Benefits of Chanting Mantras and the Science Behind It
Nada Yoga: The Science of Sound
For your specific question of quieting the mind I would recommend the following as it sets you up for experiencing causeless joy in the body and mind you have now as long as you keep at it - or if you fall off the wagon you keep getting right back on at every opportunity.
and for quieting the mind - which this kriya will take time but I can personally vouch that it works:
and finally so that you can build a strong Ida and Pingala which also helps quiet the mind:
Definitely recommend some type of simple joyful physical exercise at least a few minutes a day as well as stretching a few minutes a day if you don't already do so. Eventually simple stretches can be developed into their own specialized discipline alongside Qigong/Neigong or Yoga. The traditional Chinese fascia discipline is Jibengong and the traditional Yoga/Tantric equivalent is Angamardana.
Angamardana – Mastering Your Limbs
One of many reasons for Jibengong/Angamardana can be read in the following:
Issuing Power into the Physical: The Role of Connective Tissue