The idea that Beethoven would have needed help from his copyist to conduct the orchestra as in the film where he watches her hands -- is ludicrous.
You don't need to hear the orchestra to conduct it. You are conducting them. Not the other way around.
Anyone and everyone who conducts, does so from the written notation, unless of course it's memorized. Though helpful to be able to hear what's going on, it's not necessary ... especially at Beethoven's level, who could compose when he was deaf because he could hear the notes on the page in his head. Also, he would have been able to read the physical cues from the orchestra ... the bows of the violins etc.
You don't need to hear the orchestra to conduct it. You are conducting them. Not the other way around.
Anyone and everyone who conducts, does so from the written notation, unless of course it's memorized. Though helpful to be able to hear what's going on, it's not necessary ... especially at Beethoven's level, who could compose when he was deaf because he could hear the notes on the page in his head. Also, he would have been able to read the physical cues from the orchestra ... the bows of the violins etc.