It is common that we are told that loud noises which we can hear can be harmful to the ear. Usually we believe that if we can not hear the sound than it can not be affecting our hearing. The study done on the link below suggests that these low frequencies which we can not hear can still be damaging. The study measured faint sounds called otoacoustic emissions which are faint sounds that are naturally emitted from the inner ear as part of the hearing process. Study researchers then investigated how these faint sounds would change when the ear was exposed to low frequency sounds. With this exposure to the low frequency sounds, the sounds emitted from the ear began to slowly oscillate in frequency showing that even sounds that we can not hear can have an effect on our ears.