It is not safe to shoot a .22 caliber firearm without hearing protection, as doing so can cause immediate and irreversible hearing damage. The sound generated by a gunshot is classified as impulse noise, a short-duration, high-intensity sound pressure wave that instantly exceeds safe exposure limits. The potential for permanent hearing loss from even a single event makes using protective gear a necessary safety practice.
The Acoustic Reality of the .22 Caliber
The sound pressure level (SPL) generated by a .22 Long Rifle round easily reaches hazardous levels, dispelling the common misconception that this small caliber is quiet. Depending on the firearm and ammunition, the peak sound of a .22 LR can range from approximately 140 to over 160 decibels (dB). For comparison, the Occupational Safety and Health Administration (OSHA) sets the absolute maximum limit for unprotected exposure to impulse noise at 140 dB. The primary source of this intense sound is the muzzle blast, the rapid expansion of hot, high-pressure gases escaping the barrel after the bullet exits. Even a .22 Short can produce a peak noise level around 155 dB. Since the decibel scale is logarithmic, a small increase in the decibel number represents a massive increase in sound energy, making any exposure above 140 dB instantly damaging.
How Impulse Noise Causes Permanent Hearing Loss
Impulse noise, like a gunshot, causes trauma to the delicate structures within the inner ear’s cochlea. This short, intense pressure wave physically over-pressurizes the ear canal, causing a mechanical overload. The resulting damage is known as sensorineural hearing loss, which is generally permanent because the damaged sensory cells do not regenerate.
The high-intensity sound wave damages the stereocilia, the tiny, hair-like projections on the cochlear hair cells responsible for converting sound vibrations into electrical signals. A single, high-impulse event can shear off or permanently distort these stereocilia, leading to an immediate loss of function. A common consequence of this trauma is tinnitus, a chronic ringing or buzzing sensation, which results from the auditory nerve fibers reacting to the loss of input.
Factors Influencing Muzzle Blast Loudness
The measured decibel level of a .22 caliber round is not static and fluctuates significantly based on several variables. The type of ammunition is a major factor, contrasting standard velocity with subsonic loads. Standard velocity ammunition propels the bullet faster than the speed of sound (approximately 1,125 feet per second), creating a distinct secondary sound known as the “sonic crack” or “sonic boom.”
Subsonic ammunition is designed to travel below this threshold, eliminating the sonic crack and notably reducing the overall sound signature. The length of the firearm’s barrel also plays a considerable role in noise production. Shorter barrels, typical of pistols, allow the propellant gases to escape earlier and at higher pressure, resulting in a louder muzzle blast compared to longer rifle barrels. The shooting environment further affects the perceived loudness. Sound waves dissipate outdoors but can intensely reflect and reverberate indoors or under a covered firing line, effectively increasing the peak pressure level at the shooter’s ear.
Required Hearing Protection Standards
The solution to mitigating the extreme noise of a firearm lies in effective hearing protection, quantified by the Noise Reduction Rating (NRR). The NRR indicates the potential amount, in decibels, that the protector can reduce noise exposure. Since a .22 caliber shot can reach 160 dB, a high NRR is mandatory to bring the sound below the 140 dB safety threshold.
For impulse noise from firearms, professionals recommend an NRR of 28 dB or higher. To ensure maximum protection, especially in louder environments like an indoor range, shooters often employ double protection by wearing foam earplugs beneath earmuffs. Protection devices are categorized as either passive (standard foam plugs and muffs that provide continuous sound attenuation) or electronic. Electronic hearing protection allows lower-level environmental sounds and speech to be heard, but it instantly cuts off or limits sound transmission once impulse noise exceeds a safe level.