A bullet bow shockwave is a physical and audible wave created in the air when a bullet

Bullet

A bullet is a projectile propelled by a firearm, sling, or air gun. Bullets do not normally contain explosives, but damage the intended target by impact and penetration...

 travels at supersonic speeds; meaning faster than the speed of sound

Speed of sound

The speed of sound is the distance travelled during a unit of time by a sound wave propagating through an elastic medium. In dry air at , the speed of sound is . This is , or about one kilometer in three seconds or approximately one mile in five seconds....

.

The bullet bow shockwave is the result of air being greatly compressed at the front-most tip of the bullet as it slices through the air. As the bullet moves forward a broadening wave of compressed air trails out diagonally from the bullet tip. The sides of the bullet create a conical waveform. This conical

Cone (geometry)

A cone is an n-dimensional geometric shape that tapers smoothly from a base to a point called the apex or vertex. Formally, it is the solid figure formed by the locus of all straight line segments that join the apex to the base...

 waveform

Waveform

Waveform means the shape and form of a signal such as a wave moving in a physical medium or an abstract representation.In many cases the medium in which the wave is being propagated does not permit a direct visual image of the form. In these cases, the term 'waveform' refers to the shape of a graph...

 may be audible to a witness

Witness

A witness is someone who has firsthand knowledge about an event, or in the criminal justice systems usually a crime, through his or her senses and can help certify important considerations about the crime or event. A witness who has seen the event first hand is known as an eyewitness...

 as a whip-crack sound.

A bullet bow shockwave will be heard by any witness as long as the bullet speed is faster than the speed of sound, whether the bullet was fired from a weapon giving off an openly audible muzzle blast, or a mechanically-suppress-fired muzzle (Suppressed

Suppressor

A suppressor, sound suppressor, sound moderator, or silencer, is a device attached to or part of the barrel of a firearm which reduces the amount of noise and flash generated by firing the weapon....

weapon) blast. If a bullet is fired from a suppressed weapon, a witness can mistake the bullet bow audible shockwave whip-crack for the weapon muzzle blast audible wave, which is a separate audible event. It might be noted here that if one is involved in such an event, that the sound you hear from a suppressed weapon will not be from the point of origin. Most humans will perceive the sound as being omnidirectional or as emanating from the bullet as it passes by.