O ideal seria combinar os dois. O plug de silicone e as conchas. Plugs de plástico, custam entre R$ 1,00 e 2,00 de silicone podem custar o dobro.
As conchas custam a partir de R$ 15,00 e cada uma delas tem especificado o coeficiente de absorção e isolação acústica. Esses produtos você encontra em casas de materiais de segurança do trabalho ou em algumas casas de ferramentas profissionais.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.