New research has found that the distinctive sound of sticky tape as it peels away is caused by a series of tiny shock waves that can reach supersonic speeds.
The familiar screeching sound that erupts when clear tape is ripped off has long been treated as an everyday mystery.
Now, a new published in Physical Review Ephysicists has revealed the precise mechanism behind the noise and discovered that it is a microscopic version of a sonic boom.
Using ultra-high-speed cameras and sensitive microphones, the team led by Er Qiang Li recorded what happens when a standard strip of clear adhesive tape is removed from a glass surface. Their experiments show that the shrill sound is not produced by the simple vibration of the tape in the air, as previously thought, but by a rapid series of tiny shock waves created within the adhesive layer itself.
When the tape is removed, it does not come off smoothly. Instead, it undergoes a sudden “stick and slide” movement: the adhesive briefly adheres to the surface (stick) and then suddenly releases (slide), repeating this cycle several times per second. During each sliding phase, the adhesive does not separate evenly across the width of the tape. Instead, narrow cracks laterally tear the tape from one end to the other.
Researchers have discovered that these microscopic fractures move at surprising speeds, ranging from approximately 250 to 600 meters per second. For comparison, the speed of sound in air at room temperature is about 342 meters per second. This means that some of the fractures propagate at supersonic speeds, briefly exceeding the speed of sound itself, explains .
As each fracture propagates through the adhesive tape, it leaves behind a small ephemeral cavity that acts as a partial vacuum between the tape and the glass. Air cannot get in fast enough to fill this cavity as it forms. When the fracture reaches the edge of the ribbon, the cavity suddenly collapses as air enters, releasing a weak shock wave into the surrounding air. These repeated shock waves form a rapid “train” of sound events in miniature that, together, produce the characteristic sound of the adhesive tape being removed.
To confirm the origin of the sound, the team compared the moment when the noise reached two microphones placed on opposite sides of the tape. Temporal analysis showed that each shock wave originates from the edge of the tapeand not along the fissure itself. Although elastic vibrations in the loose tape can also generate some sound, the researchers concluded that shock waves dominate the acoustic signal.
The findings complement decades of previous research that linked tape noise to cracking and vibrations, but stopped short of pinpointing the exact cause.
