Dr. Helen Czerski investigates the extraordinary science behind sounds we’re familiar with and sounds we normally can’t hear. At the Palace of Westminster,she teams up with scientists from the University of Leicester to carry out state-of-the-art measurements to reveal how Big Ben vibrates to create pressure waves in the air at particular frequencies. With soprano singer Lesley Garrett, Helen explores the science of the singing voice. At the summit of Stromboli, Helen and volcanologist Dr. Jeffrey Johnson use a special microphone to record the extraordinary deep tone produced by the volcano as it explodes frequency far too low for the human ear to detect. Finally, at the University of Cambridge’s Institute of Astronomy, Helen meets a scientist who has discovered evidence of sound waves in space created by a giant black hole. These sounds are one million billion times lower than the limit of human hearing and could be the key to figuring out how galaxy clusters grow.