In Zayd ibn Thabit's report, the Messenger of Allah ﷺ said that, were it not for the possibility that people would stop burying their dead, he would ask Allah to let them hear the punishment in the graves that he was hearing.
The sound of grave punishment is not necessarily audible to ordinary people. Hearing or failing to hear it depends on the limits of normal perception, while its reality is affirmed through transmitted revelation and report.
The statement cautions against making ordinary human senses the sole test for the unseen.