瑜伽論記 17.517

17.517

為有斯妨，直言法爾五識率爾之心，一念則滅，設有外聲相續而至，耳識不得相續而生。

To resolve this difficulty, it simply says that by nature, the mind of the five consciousnesses in its initial instant ceases after a single moment; even if an external sound arrives in succession, the ear-consciousness cannot arise in continuous succession.