Srimathe Rangaramanuja Mahadesikaya Namaha

My fellow student while learning sandhyavandhanam told while doing Gayathri japam

1. Adhamam = Telling it loud
2. Madhyamam = Murmuring
3. Uththamam = Reciting in manas

How do adiyen.know where adiyen stand within the three? Am adiyen capable of reciting in manas directly?

Please enlighten

Dasanudasan