can't hear (oneself) think
Cannot concentrate on anything due to overwhelming noise. Can you turn down that blaring music? I can't hear myself think! There's so much construction going on during the day that you can't even hear yourself think over the chorus of jackhammers.
hear oneself think, can't
Be unable to concentrate because there is too much noise. For example, There was so much noise from the jackhammers we couldn't hear ourselves think. [Early 1900s]