What is the ruling on raising one's voice during a silent prayer when reciting Al-Fatiha and the remembrances of bowing and prostration? And does the neighboring worshippers hearing the reciter's prayer affect their devotion? And what is the ruling on doubting the pronunciation of letters like "ra" and the nunation (tanween)? And if one is not certain that they are uttered from their proper articulation points except by hearing them, does this necessitate a prostration of forgetfulness (sujood al-sahw) for the transitional takbeers like "Allahu Akbar"?

What you have mentioned about your condition is a result of your giving in to intrusive thoughts (waswasa). The best cure for them, after seeking refuge in Allah and relying on Him, is to ignore them and turn away from them. Sheikh al-Islam Ibn Taymiyyah said that intrusive thoughts disappear by seeking refuge [in Allah] and rejecting doubts. If Satan sees the servant's strength and steadfastness in truth, he will be driven away from him. Ibn al-Qayyim mentioned that waswasa regarding the articulation points of letters and over-pronunciation is from the deception of Iblis. The intention is merely to articulate the letter correctly, but Iblis leads these people beyond the limit of correct articulation and preoccupies them with exaggeration, distracting them from understanding the recitation. If you suffer from waswasa, there is no harm for you to adopt the view of the Maliki school, and the choice of Sheikh al-Islam Ibn Taymiyyah and Ibn Uthaymeen, regarding not stipulating that the reciter must hear himself. Sufficiency is achieved by moving the tongue and lips, even if you do not hear yourself. Then, turn away from any waswasa that comes to you concerning pronunciation, and you are not required to perform the prostration of forgetfulness (sujud sahwi).