Gun Range Soundproofing | Outdoor Gun Range Noise Reduction
As expanding communities continue to encroach upon rural shooting ranges, solutions to the problem of noise must be found. Remote areas that are suitable for outdoor firing ranges are becoming rare, especially around large population centers.
Indeed, expanding communities are encroaching on outdoor shooting ranges which, a number of years ago, were out in rural areas. It’s no surprise, then, that sound or noise is probably the most common source of complaints concerning shooting ranges from the community at large. Noise is sometimes defined as sound that is too loud, unexpected, uncontrollable, disagreeable, unwanted, annoying, generally irritating, or occurs at the wrong times.
- 1 Government Guidelines For Outdoor Gun Range Noise Reduction
- 2 Anatomy of Gunshot Noise
- 3 Proactive Solutions For Soundproofing a Gun Range
- 4 Other Alternatives for Soundproofing a Gun Range
- 5 Effects of Gun Fire Noise on Health
Government Guidelines For Outdoor Gun Range Noise Reduction
Noise from a variety of sources has been found to reduce the quality of life to the point that state and local laws have been enacted which place an emphasis on community noise from industrial and recreational activities.
While some of these laws include definite methods for measuring sound, and clearly define acceptable levels, others are very vague.
Additionally, agencies that range owners may have to address include the U.S. Department of Housing and Urban Development (HUD) and the Environmental Protection Agency (EPA). Both of these agencies have developed “impulsive sound” guidelines focusing on a day-night average sound level that must be met under all circumstances.
It is very important for range developers/operators to become familiar with all of the requirements and restrictions of laws applicable to their facility. Thus, the recognition of sound and how it affects the public has prompted range developers/operators to address this issue.
Anatomy of Gunshot Noise
Each gunshot normally results in two distinct noise events consisting of a muzzle blast and a supersonic projectile shock wave. This noise event is sometimes called a “crack and thump.” The muzzle blast originates at the end of the muzzle and propagates spherically in all directions.
Further, muzzle blast is directional, being louder in front of the gun compared to behind. The projectile sound is emitted all along the projectile path and continues to travel supersonically for long distances. Any firearm projectile whose velocity is over 1080 feet per second is traveling faster than the speed of sound and will often create a “mini-sonic boom.”
Proactive Solutions For Soundproofing a Gun Range
Range operators should be proactive in assessing potential problems before they impact their facility. Firearms ranges produce high levels of sound and sound waves often travel far beyond the boundaries of the range property.
These escaping sound waves may be perceived as unwanted community noise by neighboring property owners. Numerous noise reduction solutions exist; however, they vary in effectiveness. Thus, site specific solutions should be chosen.
For example, it may be in the best interest of range owners to work with the local zoning board and designate the facility as a noise park. This designation may make the range more visible to zoning planners and developers prior to the actual development of neighboring properties.
Range owners should also implement noise reduction programs. These programs should actively pursue the goal of preventing conflict before it occurs and may include the services of an acoustical consultant. Something as simple as acoustic blankets on walls can do wonders at noise reduction.
Regardless, sound levels should be measured at the property lines during normal operating times. The findings should be documented and evaluated to determine if the range satisfies local sound laws. Of course, these findings may also be used as a baseline comparison as changes are made to, and around, the range.
Sound usually travels from the source to the receiver via multiple paths known as direct and reflected paths. Sound levels can be significantly reduced by blocking, diffracting, refracting, and/or otherwise bending sound waves. These effects may be produced by installing back walls, side walls, and firing line covers complete with insulation material. Note: These structures should be made of a full wooden shingle type construction, since other construction materials are likely to ring when “excited.” The effect of enclosing a firing line in this manner is to direct the sound of the firearm in a forward direction and away from noise sensitive areas.
Other Alternatives for Soundproofing a Gun Range
1. Natural Barriers
Natural barriers such as trees and vegetation (shrubs, undergrowth, grasses, etc.) are often effective in reducing noise by providing interference between direct and reflected sound waves. Planting should be dense to form a natural barrier.
Branches and trunks provide sound scattering: High frequencies are absorbed by foliage and tree spacing, and low frequencies are absorbed by ground vegetation. Furthermore, barriers located close to the source will generate maximum effectiveness.
Backstops and berms located in conjunction with significant land features such as mountains or large hills are often very effective in reducing noise. Backstops and berms bend lower frequencies, reflect higher frequencies, and diffract both frequencies into shadow zones (the area located directly behind the barrier/berm). Typically, barrier/berm(s) should be more wide than high and are more effective the closer they are to the source or receiver. Also, increased mass increases effectiveness and there should be no openings included in the barrier.
Baffle systems are also effective in reducing noise. Effective baffles reflect sound upward into absorbing surfaces several times before the originating sound is reflected back to the shooter.
Some baffle systems cause a 50% loss in loudness. Tube ranges are another solution. Tube ranges require a shooter to fire from a fixed position, usually from a bench.
The muzzle is enclosed and muzzle blast is reduced in many directions. However, the projectile will still generate noise. Generally, tube ranges will not benefit law enforcement officers who must shoot from a variety of positions and during movement.
3. Administrative Control
Of course, some administrative rules may be adopted for sound abatement purposes. For example, “quiet hours” may be established. Quiet hours may be designated which forbid the firing of weapons during certain hours considered to be disruptive to the quality of life of the surrounding community; for example, 11:00 p.m. to 6:00 a.m. Additional quiet hours may preclude firing weapons on holidays and/or Sundays.
Quiet hours may be further extended to comply with existing noise ordinances. Of course, quiet hours may cause a problem for most departments who require dim light/no light qualifications or those who use tactical lighting systems (night vision equipment, invisible lasers, thermal imagers, etc.) during qualifications. Additional administrative controls may focus on the specific use of certain types of weapons and ammunition.
4. Effective Public Relations
Another good preventative step includes the development of a public relations effort designed to cultivate goodwill with neighboring residents and landowners. This effort should include a complaint management procedure; sensitivity to the community’s concerns; and identifying a procedure to notify the public of particularly noisy events in advance.
When handling noise complaints, officials should focus on who is complaining; identify the specific complaint; and reference and/or research any existing noise ordinances, to include noting actual language and annotated exemptions. If there is no ordinance, there should be no violation of the law.
However, it will normally benefit range operators to institute engineering and/or administrative solutions to address noise complaints which may generate costly public hearings and civil/criminal court processes.
Effects of Gun Fire Noise on Health
The body of scientific research related to effects of noise on humans is broad and growing. Except for hearing loss from noise exposure, it is fair to say that research does not always support an express correlation of a particular noise occurrence or exposure to a primary disease. It is difficult to separate an individual from the total environment such that epidemiological evidence strictly correlates noise with a particular disease. For example, human response to an acoustic danger signal such as gunfire may cause various responses related to fear in the respiratory, cardiovascular, voluntary muscle and neuroendocrine systems. Obviously, one cannot exclusively justify the acoustic properties of gunfire to human response, but rather the psychologically imbedded fear of gunfire noise is the stimulating mechanism generating respiratory, cardiovascular and endocrine stress.
On the other hand, it is well known that noise of a certain character and level evokes a physiological response from humans. Some of these responses are known to be detrimental to human safety and health.
Of the many safety and health hazards, hearing loss is the most distinctly observable and measurable effect from noise exposure. The other hazards are more difficult to measure and quantify, but there is strong antidotal and laboratory evidence that noise can be a substantial contributor to respiratory, cardiovascular and endocrine diseases. Perhaps the increase in stress as a result of noise exposure causes an increase in susceptibility to disease and infection.
While no one has yet shown that noise inflicts any measurable damage to the heart itself, an expanding body of evidence strongly suggest a link between exposure to noise and the development and aggravation of a number of heart disease problems. This is probably because of the fact that noise causes stress and the body reacts with increased adrenaline, changes in heart rate and elevated blood pressure. Noise is one of several environmental causes of stress. As such, researchers cannot say with confidence that noise alone caused the heart circulatory problems they have observed. What they can point to is a statistical relationship apparent in several field and laboratory studies, which support the likelihood of noise being a causal factor for heart function abnormalities. Particularly susceptible to harmful effects of noise are heart patients who already suffering from heart disease.
The link between noise and many disabilities or diseases has not been conclusively proved. But, like cigarette smoking statistical correlation with diseases of various sorts, the body of evidence connecting intruding noise exposure and disease is growing.
But even without further evidence, it is universally accepted that the danger of noise intrusion to human safety and health is real.
1.4 Acoustically, what is gunfire noise?
Gunfire noise is characterized as “impulsive and transient” in character, meaning that a sound pressure peak occurs in a short interval of time. For example, typical gunfire noise may have a sound pressure peak of about 150 to 175 dB occurring over a period of several hundred milliseconds. A single gunfire implusive noise may be heard as a discrete event occurring in otherwise quiet conditions, or it may be superimposed upon a background of steady-state on-going noise.
2.0 Short Term Effects
Impulse noise such as that from gunfire (and gun ranges) leads to imbedded “protection” reactions of the human physiology. Short term effects range widely from a brief eye blink to after-effects such as headache, fatigue and emotional distress; these after-effects may be present for hours after exposure. Short-term effects may be categorized as “startle response”, “orienting reflex” and “defense reflex”. Startle response is the sudden stimuli that gets our attention and disrupts whatever activity in which we may be engaged. Orienting reflex is the response to locate and identify the source of disruptive noise, and defense reflex is the unconscious and involuntary response to a perceived threat of danger or harm to our safety. These effects are particularly acute for unexpected impulse noise such as that characterized by gunfire.
2.1 Startle Response
Startle response is characterized a widespread flurry of activity in voluntary muscle. Imbedded in the human makeup is a mental and physical conditioning to automatically respond to any stimuli that may be interpreted as a threat or danger. The purpose of startle response appears to be protective. A gunfire burst of noise will illicit sudden and immediate startle response. Again, the most immediate danger to safety of an individual is the interruption of an ongoing task, which may place the individual in a harmful or life-threatening situation.
In readiness for dangerous and harmful situations, our bodies make automatic and unconscious responses to sudden or loud noises such as noise from gun ranges. Blood pressure rises, heart rate and breathing speed up, muscles tense, hormones are released into the blood stream and perspiration appears. The changes occur even during sleep.
Military studies show that even if we think we can become accustomed to repeated exposure to gunfire noise, biological changes still take place inside us, posturing us for defensive physical activity if necessary.
Gun range noise does not have to be loud to bring on these responses. Our bodies and subconscious minds interpret the noise as a threat and the consequent result is regular and predictable changes in the body.
2.2 Muscular Response
Research conclusively shows evidence that the muscle groups are stimulated to reflex by introducing noise. The response can be visually prominent and even violent as many muscle groups may respond at once to certain sound stimuli – this is particularly obvious when exposed to impulse noise and is often classified as “startle response” (above). Such muscle response is clearly visible to an observer. On the other hand, minimal muscle responses may not be visually apparent; in these cases, muscle tension is detected and measured by electrical activity of the muscle in laboratory studies.
The most likely practical implications are the occurrence of muscle stimuli causing involuntary muscle movements or modification of movements that can interfere with some active critical motor task. For example, should an individual be carrying a dangerous chemical fluid, the extension/contraction of arm and leg limbs can conceivably cause a spill and consequent serious damage to the individual.
Interruption of mental focus, alteration or interruption of a task as a consequence of a loud noise such as gunfire can lead to immediate short-term negative consequences, sometimes serious.
2.3 Respiratory Reflexes
The respiratory system functions to regulate the gaseous content of the blood, including the partial pressures of carbon dioxide and oxygen and to stabilize various aspects of body chemistry.
When exposed to gun range noise, breathing is slowed: minimum breathing movements occur at about 15 to 20 seconds after exposure after which, breathing generally returns to normal.
2.4 Heart and Circulation Effects
“We now have millions with heart disease, high blood pressure, and emotional illness who need protection from the additional stress of noise.” (Dr. Samuel Rosen, Mt. Sinai Hospital)
Research studies show that short term effects of a sudden loud noise of no specific meaning causes changes in heart rate and reduction of diameter of blood vessels in peripheral regions. Exposure to sudden noise (with no meaning) has been shown to cause an increase in heart beat from a low of about three beats per minute to an average high of about eleven beats per minute. Should the noise be identified with a source such as a threat of harm (gunfire noise, e.g., having meaning), the heart and circulation response is substantially intensified over that of noise with no specific meaning.
Stimulus and recovery of the heartbeat exhibits a pattern of sudden rise in heartbeat coincident with a burst of gunfire noise and an undulating reduction in heartbeat with the decay and cessation of the disturbing noise. Recovery of heartbeat to normal level typically occurs in ten to twenty seconds.
Studies performed to determine the extent of changes in the diameter of the small blood vessels in response to sudden noise show that constriction of these vessels (vasoconstriction) begins to occur at about 70 dB in a low-noise background environment. With increasing noise level, vasoconstriction has been measured from a low of 21 percent at low level short-duration intruding noise level of about 70 dB to a high of 64 percent at noise level of about 100 dB. Recovery of the vessels after a noise event is usually measured in seconds. Consequent with vasoconstriction of blood vessels is a rise in blood pressure during and shortly after exposure to gunfire noise.
The time and pattern of stimulus and recovery is related to the character of noise and its content. If meaning is connected to the noise, such as “gunfire”, voluntary muscle response (startle and defense reflex) will magnify the level of heart effects described above.
Research results also show that the influence of external or internal environment affects the degree of response to sudden noise. For example, other powerful physiological responses such as stimuli due to exercise, heat, cold, or emotion will obscure or prevent the degree of vasoconstriction effect to short sudden noises.
Other studies focusing on the effects of impulse noise (such as gunfire) on blood pressure conclusively show that there is a drastic reduction of diastolic blood pressure while the systolic blood pressure is not substantially affected.
2.5 Other Physiological Responses
Our bodies are conditioned to respond to dangerous and harmful situations; they automatically interpret danger signs and respond according to innate conditioning. We automatically and unconsciously respond to sudden or loud sounds. Most noise in our society does not signal danger; however, our bodies still react as if these sounds were always a threat or warning. One can multiply these body reactions to common noise by many-fold when one is exposed to loud and sudden noise such as fire alarms, door slamming, gunfire, glass breakage, etc.
The idea that people get used to noise is a myth; even when we think we have become accustomed to noise, biological changes still take place inside us, preparing us for physical counteraction to the implied threat if necessary. Noise does not have to be loud to invoke these responses. Low impulsive noise levels can cause regular and predictable changes in the body.
“Loud noises once in a while probably cause no harm. But chronic noise situations must be pathological. Constant exposure to noise is negative to your health.” Dr. Gerd Jansen, Ruhr University.
2.5.1 Eye Pupil Responses
Noise can cause a dilation of the eye pupil. With about 75 dB of noise with no meaning, the eye begins to dilate. At 90 dB, an increase in pupil diameter of about five percent has been measured. Dilation varies with noise level. Return of the pupil diameter to pre-stimulus occurs very rapidly with cessation of noise.
No studies were found relating pupil response to impulse noise with meaning. However, it is believed that effects of the pupil dilation observed with noise of no meaning will be substantially amplified in response to noise with meaning such as gunfire noise.
2.5.2 Vestibular Effects
Extensive studies have been completed on the effects of high noise levels on equilibrium. The ability of humans to perform balancing tasks is impaired by high noise levels characterized by both broad band noise and narrow band noise.
2.5.3 Gastrointestinal Effects
Though studies are not distinctively conclusive on the total effect of high and/or sudden noise level on gastrointestinal activity (digestive and elimination system), some studies show that prolonged exposure to high noise level indicated a significantly delayed and lengthened colon motility. The studies reveal that the alterations resemble the well-known dysfunction recognized as “the irritable bowel syndrome.” Early researchers found that workers chronically exposed to noise developed conspicuous digestive changes that were believed to be lead to ulcers.
2.5.4 Lungs and Upper Respiratory Tract
Studies suggest that when humans are exposed to gunfire noise, constrictive reflex of the bronchia occur, thus decreasing respiration and the flow of oxygen to the body. Recovery to normal is a slow relaxation of the bronchia and return to normal respiration.
2.5.5 Biochemical and Endocrinological Reactions
Clear evidence from studies show that the release of adrenaline is significantly increased by exposure to noise. This hormonal stress reaction causes an increase of the membrane permeability and a decrease of concentration gradients at the cell membranes. Electrolyte alterations induced by noise stress have been demonstrated. In one study, a group of test subjects lost five percent of the magnesium content in the blood during a test period of noise exposure.
3.0 Effects on Sleep
Numerous studies show that gunfire noise such as coming from military training camps evoked brain and heart reactions in sleeping subjects. Studies show in general that intruding noise into the sleep environment cause strained wakefulness and intensified fatigue. Even exposure to high noise levels during a daytime period has after-effects on a subsequent noise-undisturbed night sleep. Recovery from noise-disturbed sleep is long and can last for several sleep periods.
It has been determined that our response to noise before and during sleep varies widely among age groups. Elderly and sick people are especially sensitive to disruptive noise. Elderly people are more easily awakened by noise and once awake, have more difficulty returning to sleep.
Community noise complaint studies show that of the kinds of annoyance related to noise intrusion causing the interruption of rest, relaxation and sleep was the most prominent cause of many peoples’ complaints.
Investigators of noise effects have learned that when noise interferes with our sleep, it demands that our bodies adapt. Implications of these demands on our general health and performance are not yet well understood. However, it is known that we need restful sleep and many are not getting it because of exposure to noise and other stimuli.
“no man can get a night’s rest.” (Chaucer, 1350, complaining of noise by blacksmiths)
4.0 Stress Effects
Stress is considered by most investigators to cause the prominent physiological effects of noise. The complex human system is constantly trying to achieve stabilization and physiological equilibrium. This process goes on during both waking and sleeping hours. Along with other stressors, heat, cold, fear, rage or emotions, etc., noise has been shown to affect elementary responses and activate stress of one sort or another to the body systems. For example, noise has been identified as the most prominent overall stress factor at the working place.
No one is immune from stress. It is known that noise can produce serious physiological and psychological stress. Most try to ignore intruding noise, but the fact is the ears are not equipped with earlids and intruding noise continues to bombard our system and the body and mind continues to respond, sometimes with extreme tension, particularly when fear response is invoked.
5.0 Mental and Social Well-Being Effects
The most obvious price one pays when exposed to noise from gun ranges is the annoyance frequently experienced from gunfire noise. When gun range noise causes chronic and repeated noise exposure, initial annoyance may be transformed into more extreme emotional responses and behavior. Newspaper files and police records contain reports of incidents that point to not only gun range noise but also other loud and repeated noises as a trigger of extreme behavior.
Some examples of noise-induced extreme behavior illustrating extreme behavior are presented in headline form below.
“Noisy Neighbors Helped Drive English Man to Suicide, Coroner Finds.” (Headline, The Daily Telegraph, April 1, 1998)
“New Zealand Man Threatens to Shoot Down Air Force Jet Because of Noise.” (Headline, The Dominion, October 23, 1997)
Pennsylvania Man Kills Dirt Biker Over Noise (Headline, The Pittsburgh Post-Gazette, September 8, 1997)
Indiana Man Enraged at Noisy Teen-Agers Charged for Firing a Gun (Headline, The Indianapolis News, July 29, 1997)
New York Man Found Guilty of Killing Neighbor After Feud About Noise (Headline, The New York Times, March 20, 1007)
“The noise, The Noise. I just couldn’t stand the Noise.” (Suicide note left by a desperate homeowner.) – Quote from: Noise: A Health Problem, EPA, 1974.
Some people cope with loud noise by directing their anger and frustration inward, by blaming themselves for being upset and by suffering in silence. Others resort to a denial of the problem altogether, considering themselves so tough that noise does not bother them. Others deal with noise more directly by taking sleeping pills, wearing ear plugs, increasing visits to their doctor, keeping windows closed, rearranging sleeping quarters, spending less time outdoors and complaining to government officials.
Evidence shows that these ways of contending with noise are unlikely to eliminate the noise or any underlying annoyance. Most people who cannot cope with noise in these ways typically direct their anger at others and become more argumentative and moody, though not necessarily violent. This noise-induced, anti-social behavior is considered to be far more prevalent than one may realize.
Research does not irrefutably conclude that noise by itself causes mental illness. There is, however, strong evidence that noise-related stress can aggravate already existing emotional disorders. Research in both the U.S. and England reveals that people living near airports have a higher rate of admission to psychiatric hospitals. Likewise in industry, prolonged noise exposure may lead to a larger number of psychological problems among workers.
Noise Implications to Human Health and Safety
It is widely accepted that as a risk factor for defined diseases, noise seems to be less important than smoking, eating habits, physical exercise and other habits of daily life. All of these factors may adversely affect health only after several years. Many studies clearly support the hypothesis that noise has to be considered as a risk factor to health and safety, particularly leading to disorders such as hypertension, coronary heart disease and biochemical changes.
Long Term Effects of Noise
Specific descriptions of the long-term effects of noise on human physiology are difficult and fraught with uncertainty. This is primarily because it is not reasonable to isolate humans from all other stimuli that have similar or identical effects on human physiology as those of noise and exclusively determine the direct effects of noise.
Long-term effects can be measured in hours, days or even longer. Researchers think long-term effects are attributed to repeated noise stimulation that produce short-term responses and are believed to be cumulative in total effect. Investigators accept that long-term effects of repeated noise exposure change the rate of hormonal secretion of into the bloodstream and thus modifying hormone concentrations for hours, days or longer.
For cardiovascular disorders, experimental results clearly demonstrate that long-term effects of noise exposure on vasoconstriction can be connected to the state of health of an individual as related to noise.
Research conclusively show that manifestations of human response to sudden noise such as from gunfire may include one or all of the following.
- Firm closure of the eyes.
- Facial grimaces of a characteristic nature.
- Bending of the knees.
- General inward flexion of the body.
- Increased neck and shoulder muscle tension tending to draw the head downward.
- Random foot movement.
- Elevation of the arms bringing the hand toward the face with an inward rolling of the forearms.
Manifestations of Noise on General Health
In conclusion, present conditions may exclude some ranges from sound abatement concerns, but situations may rapidly change on the range or in the area surrounding the range, so some type of noise reduction plan should be developed. More often than not, good public relations with range neighbors, community leaders and the community at large is essential. Ranges operated by personnel representing agencies intent on only reacting to a problem (informal and/or formal complaint) after it transpires are likely to see their range shut down and are probably headed for additional legal action.