Hola a todos:Estoy realizando una i

Hola a todos:
Estoy realizando una investigación en que tengo que grabar las voces de ciertas personas. El otro día le dije a una amiga que podría necesitar grabarle la voz, pero ahora sé que no es necesario. Hoy quiero decirle que puede participar en la investigación, pero no es obligatorio. ¿Puedo decir lo siguiente? ¿Suena nautral?

Results (English) 1:

Hello everyone:I am doing a research in which I have to record the voices of certain people. The other day I told a friend that he might need to record her voice, but now I know that it is not necessary. Today I want to tell you that you can participate in the investigation, but it is not mandatory. Can I say the following? Sound nautral?

Results (English) 2:

Hello everyone
I am doing research that I have to record the voices of certain people. The other day I told a friend who may need to record your voice, but now I know it's not necessary. Today I want to tell you that you can participate in research, but not required. Can I say this? It sounds nautral?

Results (English) 3:

Hi everyone:I am conducting a Research in which I have to record the Voices of certain people. The other day I told a friend that may need to record your Voice, but now I know that's not necessary. Today I want to tell you that you can participate in the investigation, but is not mandatory. I can say the following? Nautral Sounding?