473. Interrupting Between a Bracha and Its Action

Brachos 1:7

A person should recite brachos loud enough so that he can hear what he is saying. However, one still fulfills his obligation if he does not recite it out loud, whether he recited the bracha quietly or only said it in his heart.

Brachos 1:8

When reciting a bracha, one may not interrupt between the bracha and the thing that is the reason for which he is reciting the bracha. If one does interrupt with another activity, he must recite the bracha again. If one makes an interruption that is relevant to the bracha, he does not repeat it. An example is one who recites a bracha over bread and before eating must request salt or something else relevant to the act in question. In such a case, one does not repeat the bracha.