The Secret of Hell’s Ladder The Biomedical Building at Brown University has an elevator called the “Ladder to Hell”. Once the elevator door is closed, although no what abnormality will be heard, passengers can feel their ears vibrating about four times a second and their bodies vibrating without coats. This is a typical old elevator, with an inner diameter of about 2 m × 2 m × 3 m, a buzzing fluorescent lamp and a curved blade of the fan on the ceiling. All these make it a perfect low frequency acoustic resonator. Even if one takes the elevator to only two floors, one will feel sick and uncomfortable. The power of this fan is not large, but the broken Read More …