In the heart of a moonlit forest, where shadows danced with the secrets of the night, a chilling silence reigned. The air was thick with anticipation, as if the very trees held their breath in anticipation of some unspoken, spectral occurrence. It was then, amidst the ethereal hush, that a sudden, bone-chilling shriek sound shattered the stillness, sending shivers down the spine of anyone.
The shriek is a high-pitched, piercing sound that can send shivers down one’s spine. It is a sound that evokes a sense of alarm, fear, or distress. The shrillness and intensity of a shriek can vary, but it often serves as a natural warning signal, alerting us to potential dangers or urgent situations. In nature, animals often emit shrieks as a means of communication or defense.
In human culture, the shriek has been used in horror films to create suspense and tension, as well as in music to convey emotions of anguish or despair. It is a sound that can be both unsettling and attention-grabbing, making it a powerful tool for conveying a range of emotions and messages.
The composition of a shriek typically involves a rapid and fluctuating oscillation of sound waves at a high frequency. This creates a sensation of discomfort or disturbance in the listener, triggering a physiological response known as the “fight or flight” reaction. The human ear is particularly sensitive to high-pitched sounds, and a shriek can easily cut through ambient noise.
What causes a shriek sound in machinery?
A shriek or squealing sound in machinery typically indicates a problem with moving parts, friction, or wear and tear. There are several common causes for such sounds in machinery:
- Lubrication Issues: One of the most common causes of shrieking sounds in machinery is a lack of proper lubrication. When moving parts don’t have enough lubrication, they can generate friction and heat, leading to squealing noises. Regular maintenance and lubrication can help prevent this issue.
- Worn or Damaged Bearings: Bearings are used in many types of machinery to reduce friction between moving parts. When bearings wear out or become damaged, they can emit high-pitched squealing sounds. Replacing or repairing the bearings is typically necessary to resolve the issue.
- Misaligned Parts: Misalignment of components in machinery can lead to uneven contact and increased friction, causing squeaking or shrieking noises. Proper alignment of parts is crucial to prevent this problem.
- Belt Issues: In machinery that uses belts (such as conveyor systems or engines with drive belts), worn or misaligned belts can produce squealing noises. Replacing or realigning the belts can often solve the problem.
- Loose Fasteners: Loose nuts, bolts, or other fasteners can create vibrations and lead to noise in machinery. Regular maintenance and tightening of fasteners can help prevent this issue.
- Worn or Damaged Gears: Gears that are worn out or damaged can produce a shrieking sound as they engage with each other. Replacing or repairing the damaged gears is necessary in such cases.
- High-Speed Rotation: In some cases, machinery operating at very high speeds can produce high-pitched sounds due to the rapid movement of components. Proper design and maintenance can help minimize this issue.
- Foreign Objects or Debris: Sometimes, foreign objects or debris can get lodged in machinery, causing parts to rub against them and produce unusual sounds. Regular cleaning and inspection can help prevent this issue.
- Bearing Preload: In some precision machinery, a specific level of preload is applied to bearings to maintain their rigidity. Incorrect preload settings can lead to noise issues.
- Belt Tension: In machinery with belts, improper tensioning can cause noise problems. Ensuring the correct tension is applied to belts can resolve this issue.
It’s essential to address shrieking sounds in machinery promptly because they often indicate mechanical problems that, if left unattended, can lead to more significant issues, reduced efficiency, and potentially costly repairs or downtime.
How can you describe the pitch of a shriek sound?
The pitch of a shriek sound refers to how high or low the sound is perceived by the human ear. It is one of the fundamental characteristics of sound and is primarily determined by the frequency of the sound waves. Here’s how you can describe the pitch of a shriek sound:
- High-Pitched: A shriek sound is generally described as high-pitched. This means that it has a relatively high frequency, and it sounds sharp and piercing to the ear. High-pitched sounds have a shorter wavelength, and they typically evoke a sense of urgency or discomfort.
- Squealing: “Squealing” is a word commonly used to describe high-pitched, shrieking sounds. It conveys the idea that the sound is sharp, shrill, and often unpleasant to listen to.
- Piercing: Another term often used to describe the pitch of a shriek sound is “piercing.” This suggests that the sound has a penetrating quality and can cut through other sounds or ambient noise.
- Ear-splitting: This expression emphasizes the loud and high-pitched nature of the shriek sound. It suggests that the sound is so intense that it feels like it could “split” or damage one’s ears.
- Highbrow: In musical terminology, the pitch of a shriek sound would be considered in the higher registers or treble range. It is the opposite of a low or bass sound.
- Similar to a Whistle: A shriek sound may be compared to a whistle, which is a device that produces a high-pitched tone. This comparison helps convey the idea of the sound‘s pitch to someone who may not be familiar with the specific sound.
Are shriek sounds typically high-pitched or low-pitched?
Shriek sounds are typically high-pitched. A shriek is characterized by a sharp, piercing, and often unpleasant high-frequency sound. It is associated with a higher pitch on the auditory spectrum.
Low-pitched sounds, on the other hand, are deeper and have a lower frequency. Shrieks are the opposite of low-pitched sounds like deep rumbling, bass notes, or growls, which have a lower frequency and are often perceived as more resonant and less sharp.
What safety measures can reduce the risk of hearing shriek sounds in industrial settings?
To reduce the risk of hearing shriek sounds in industrial settings and protect workers from potential noise-related hazards, several safety measures can be implemented:
- Engineering Controls:
- Noise Barriers and Enclosures: Install noise barriers or enclosures around noisy equipment to contain and reduce sound propagation.
- Soundproofing: Use soundproofing materials to reduce noise emissions from machinery or processes.
- Vibration Isolation: Implement vibration isolation measures to reduce the transmission of noise through structures and equipment.
- Equipment Maintenance: Regularly inspect and maintain machinery to ensure that it operates smoothly and quietly, reducing the likelihood of unexpected shriek sounds.
- Job Rotation: Rotate employees through different tasks to limit their exposure to noisy environments.
- Shift Scheduling: Schedule noisy tasks during times when fewer employees are present to minimize overall exposure.
- Training: Provide training on noise hazards, the proper use of personal protective equipment (PPE), and safe work practices to raise awareness among workers.
- Noise Policies: Develop and enforce workplace policies and procedures related to noise control and hearing conservation.
Personal Protective Equipment (PPE):
- Hearing Protection: Provide workers with appropriate hearing protection devices, such as earplugs or earmuffs, and ensure they are trained in their proper use.
- Fit Testing: Conduct fit testing for hearing protection to ensure it fits properly and provides the desired level of protection.
- Regular Noise Assessments: Conduct regular noise assessments to identify areas with high noise levels and assess the effectiveness of noise control measures.
- Audiometric Testing: Implement a hearing conservation program that includes baseline and periodic audiometric testing to monitor employees’ hearing health.
- Ensure compliance with local, national, and international regulations and standards related to noise exposure limits and workplace safety.
- Consider upgrading older machinery with newer, quieter models to reduce noise emissions.
- Encourage employees to communicate about unusual or potentially hazardous sounds they hear, which may indicate machinery problems.
- Develop emergency procedures for responding to unexpected loud noises, including shutting down equipment and evacuating affected areas if necessary.
- Implement a proactive maintenance program to prevent unexpected failures and shrieking sounds due to worn or damaged components.
Noise Hazard Signs and Warnings:
- Use warning signs and signals to alert employees to noisy areas and the need for hearing protection.
Implementing a combination of these safety measures can help reduce the risk of hearing shriek sounds in industrial settings, protect workers’ hearing, and create a safer work environment overall. It’s essential to conduct regular assessments and adapt control measures as needed to address changing conditions and emerging hazards.
Can you identify common sources of shriek sounds in a household?
Shriek sounds can also occur in a household setting. While household shrieks may not be as loud or severe as those in industrial settings, they can still be annoying or indicate issues that need attention. Common sources of shriek sounds in a household include:
- Faucet or Shower Drips: A dripping faucet or showerhead can create a high-pitched, repetitive sound.
- Faulty Toilet Fill Valve: A malfunctioning toilet fill valve can produce a shrieking sound as it refills the tank.
- Refrigerator or Freezer Fan: A malfunctioning fan in the refrigerator or freezer can emit a high-pitched noise.
- Washing Machine or Dryer: Issues with bearings, belts, or motors in laundry appliances can lead to squealing sounds.
- Dishwasher: A malfunctioning water inlet valve or pump can create shrieking or whining noises.
- Microwave: Faulty components like the turntable motor or cooling fan can produce high-pitched sounds.
HVAC (Heating, Ventilation, and Air Conditioning):
- Furnace or Boiler: Problems with fans, motors, or air filters in heating systems can result in high-pitched noises.
- Air Conditioning Unit: Issues with the compressor, fan, or blower motor can lead to shrieking sounds.
Doors and Windows:
- Hinges and Latches: Worn-out or improperly lubricated door and window hinges or latches can squeak when opened or closed.
Smoke Detectors and Alarms:
- Low Battery Warning: Smoke detectors and carbon monoxide alarms may emit a high-pitched chirping sound when their batteries are low.
- Cats and Dogs: Some pets can make high-pitched vocalizations or yowling sounds, especially during mating or when in distress.
- Electrical Wiring: Loose or damaged electrical connections can sometimes emit high-frequency noises, which can be a safety concern.
- As houses settle and experience changes in temperature and humidity, certain structural elements may produce creaking or high-pitched noises.
Insects and Pests:
- Some insects, such as cicadas, crickets, or certain types of beetles, can produce shrill noises during their mating or feeding activities.
- Children’s Toys: Electronic toys and gadgets with sound effects may produce high-pitched sounds that children find entertaining but adults may consider noisy.
- Wind whistling through cracks or gaps in windows or doors can create a high-pitched noise indoors.
Identifying and addressing the source of household shriek sounds may involve maintenance, repairs, or replacements of affected components. Regular home maintenance and inspections can help prevent and resolve these issues before they become more significant problems.
What materials can muffle or dampen shriek sounds effectively?
Muffling or dampening shriek sounds effectively requires materials that can absorb, block, or dissipate sound energy. The choice of material depends on the specific source and frequency of the shriek sound, as well as the context in which you need to reduce the noise. Here are some materials commonly used for this purpose:
Soundproof Curtains and Drapes:
- Heavy, dense curtains or drapes with soundproofing layers can effectively block and absorb noise, including high-pitched sounds.
Acoustic Foam Panels:
- Acoustic foam panels, often used in recording studios, can absorb high-frequency sounds and reduce reverberation.
Mass-Loaded Vinyl (MLV):
- MLV is a dense, flexible material that can be used as a barrier to block sound transmission. It is often used in walls, ceilings, and floors.
- These panels, which come in various materials like fiberglass or foam, can absorb and dampen sound, reducing the reflection of high-pitched noises.
- Cork flooring can help reduce impact noise and footstep sounds, which can be beneficial for muffling sounds from below.
- Installing acoustic insulation within walls, ceilings, and floors can help reduce sound transmission and dampen shriek sounds.
Weatherstripping and Sealants:
- Properly sealing gaps and cracks around windows, doors, and other openings can prevent outdoor noise, including high-pitched sounds, from entering your home.
Carpet and Rugs:
- Thick carpets and rugs can help absorb and dampen sound, reducing the reflection of high-pitched noises.
- Using acoustic underlayments beneath flooring materials can reduce impact noise and high-pitched sounds.
- Soundproof drywall is specifically designed to block and absorb sound, making it effective for reducing noise, including high-pitched shrieks.
- Special acoustic paint can be applied to walls and ceilings to add a sound-absorbing layer.
Massive and Dense Building Materials:
- Materials like concrete, brick, and stone are naturally dense and can block sound effectively when used in construction or as barriers.
- Indoor plants can help absorb and diffuse sound, improving overall acoustics and reducing noise.
- Installing double-glazed windows can provide an additional barrier against outdoor noise, including high-pitched sounds.
Custom Soundproofing Solutions:
- In some cases, custom solutions such as soundproofing drywall, acoustic ceiling clouds, or isolation mounts for machinery may be required for specific noise problems.
It’s important to note that the effectiveness of these materials depends on the noise source, the construction of the space, and the intended level of noise reduction. In some cases, a combination of materials and methods may be necessary to achieve the desired results.
How do animals use shriek sounds for communication?
Animals use shriek sounds for a variety of purposes, including:
- To signal danger. When an animal is in danger, it may shriek to warn other animals of the threat. This is common in prey animals, such as deer and rabbits, which use their shrill cries to alert their herd to the presence of a predator.
- To attract mates. Some animals, such as bats and frogs, use shriek sounds to attract mates. The sound of the shriek may indicate the size, strength, or health of the animal, making it more attractive to potential mates.
- To establish dominance. In some animals, such as chimpanzees and gorillas, shriek sounds are used to establish dominance within the social hierarchy. The animal that produces the loudest or most piercing shriek is usually seen as the dominant animal.
- To defend territory. Some animals, such as squirrels and birds, use shriek sounds to defend their territory from intruders. The sound of the shriek may startle or intimidate the intruder, making them less likely to trespass.
- To express pain or distress. When an animal is in pain or distress, it may shriek to communicate its discomfort to other animals. This is common in injured animals, which use their shrieks to attract help from their mates or herd members.
The specific meaning of a shriek sound can vary depending on the animal species and the context in which it is produced. However, in general, shriek sounds are a powerful form of communication that animals use to convey a variety of messages.
What are some common psychological reactions to sudden shriek sounds?
Sudden shriek sounds can trigger a variety of psychological reactions, including:
- Startle response: This is a natural reflex that occurs when we are suddenly startled by a loud noise. The startle response can cause us to jump, gasp, or cry out.
- Fear: Sudden shriek sounds can trigger a fear response, which is a feeling of anxiety or apprehension. This fear response can be caused by the association of the sound with a past negative experience, such as a car accident or a physical assault.
- Disgust: Some people may experience disgust when they hear a sudden shriek sound. This is because the sound can be associated with pain, injury, or death.
- Anger: Sudden shriek sounds can also trigger anger, especially if the sound is perceived as being threatening or aggressive.
- Tension: Sudden shriek sounds can cause muscle tension and anxiety. This is because the body is preparing for a fight-or-flight response.
- Post-traumatic stress disorder (PTSD): In some cases, repeated exposure to sudden shriek sounds can lead to the development of PTSD. PTSD is a mental health condition that can cause symptoms such as flashbacks, nightmares, and anxiety.
The severity of the psychological reaction to a sudden shriek sound can vary depending on the individual and the context in which the sound occurs. For example, a person who has experienced a traumatic event involving a sudden shriek sound may be more likely to have a strong reaction to the sound than someone who has not had such an experience.
If you are experiencing negative psychological reactions to sudden shriek sounds, it is important to seek help from a mental health professional. They can help you to understand your reactions and develop coping mechanisms.
How can you distinguish between a shriek sound and a squeal sound?
The main difference between a shriek sound and a squeal sound is the pitch. Shrieks are typically higher-pitched and more piercing than squeals. Shrieks are also often associated with fear or pain, while squeals are more often associated with excitement or pleasure.
Here is a table summarizing the key differences between shriek sounds and squeal sounds:
Here are some examples of shriek sounds:
- The sound a woman makes when she is startled
- The sound a child makes when they are in pain
- The sound a car makes when it brakes suddenly
- The sound a bird makes when it is being attacked
Here are some examples of squeal sounds:
- The sound a pig makes when it is happy
- The sound a baby makes when they are laughing
- The sound a dog makes when they are excited
- The sound a cat makes when they are being petted
It is important to note that these are just general guidelines. There is some overlap between shriek sounds and squeal sounds, and the exact meaning of a sound can vary depending on the context. For example, a squeal of pain can be just as loud and piercing as a shriek of fear.
Ultimately, the best way to distinguish between a shriek sound and a squeal sound is to listen to the sound and consider the context in which it is being made.
What are the potential health effects of prolonged exposure to shriek sounds?
Prolonged exposure to shriek sounds can have a number of potential health effects, including:
- Hearing loss: Shriek sounds are typically very loud, and prolonged exposure to loud noise can damage the hair cells in the inner ear, which are responsible for hearing. This can lead to permanent hearing loss.
- Sleep disturbance: Shriek sounds can be very disruptive to sleep, making it difficult to fall asleep or stay asleep. This can lead to fatigue, irritability, and difficulty concentrating.
- Stress: Shriek sounds can be a source of stress, especially if they are unexpected or uncontrollable. This can lead to a number of physical and psychological problems, such as headaches, muscle tension, and anxiety.
- Annoyance: Shriek sounds can be very annoying, and prolonged exposure can lead to a feeling of annoyance or irritation. This can make it difficult to focus or relax.
- Irritability: Shriek sounds can also make people more irritable. This can lead to arguments, outbursts of anger, and difficulty getting along with others.
- Increased blood pressure: Prolonged exposure to loud noise has been linked to an increased risk of high blood pressure. This is because loud noise can cause the body to release stress hormones, which can raise blood pressure.
- Heart disease: Loud noise has also been linked to an increased risk of heart disease. This is because loud noise can cause the heart to work harder, which can damage the heart muscle.
The severity of the health effects of prolonged exposure to shriek sounds can vary depending on the individual and the level of exposure. Some people may be more sensitive to noise than others. If you are concerned about the potential health effects of prolonged exposure to shriek sounds, it is important to talk to your doctor.
What tools or equipment are used to measure the intensity of a shriek sound?
There are a few different tools or equipment that can be used to measure the intensity of a shriek sound.
- Sound level meter: A sound level meter is a device that measures the intensity of sound in decibels (dB). It can be used to measure the intensity of any sound, including shriek sounds.
- Oscilloscope: An oscilloscope is a device that can be used to visualize sound waves. It can be used to measure the frequency, amplitude, and duration of a sound wave, all of which can be used to determine the intensity of the sound.
- Frequency analyzer: A frequency analyzer is a device that can be used to measure the frequency components of a sound wave. The frequency of a sound wave is the number of times it vibrates per second, and it is measured in hertz (Hz). The intensity of a sound wave is related to its frequency, so a frequency analyzer can be used to determine the intensity of a sound.
- Digital recording device: A digital recording device can be used to record a shriek sound and then measure its intensity using software. There are many different digital recording devices available, such as smartphones, tablets, and laptops.
The best tool or equipment to use to measure the intensity of a shriek sound will depend on the specific application. For example, if you need to measure the intensity of a shriek sound in real time, then a sound level meter would be the best tool to use.
However, if you need to measure the frequency components of a shriek sound, then a frequency analyzer would be the best tool to use.
How can I prevent my car brakes from making a shriek sound?
Here are some tips on how to prevent your car brakes from making a shriek sound:
- Inspect your brake pads regularly. Brake pads wear down over time, and when they get too thin, they can start to make a squeaking noise. You should inspect your brake pads every 10,000 to 15,000 miles or as recommended by your car’s manufacturer.
- Clean your brake rotors. Brake rotors can become dirty and corroded over time, which can cause them to make a squeaking noise. You can clean your brake rotors with a brake cleaner and a wire brush.
- Lubricate your brake components. Some of the components in your brake system, such as the caliper pins and slides, need to be lubricated to prevent them from squeaking. You can use a high-temperature brake lubricant to lubricate these components.
- Bed in your new brake pads. When you install new brake pads, it is important to bed them in properly. This process helps to create a smooth surface on the brake pads and rotors, which can help to prevent squeaking.
- Have your brakes serviced by a professional. If you have tried all of the above and your brakes are still making a squeaking noise, it is best to have them serviced by a professional. They can inspect your brakes and identify the problem.
Here are some of the most common causes of brake squeal:
- Worn brake pads: As brake pads wear down, they can become thinner and produce a squeaking noise when they rub against the brake rotors.
- Dirty or corroded brake rotors: Brake rotors can become dirty or corroded over time, which can cause them to make a squeaking noise when they rub against the brake pads.
- Loose or damaged brake hardware: The brake hardware, such as the caliper pins and slides, can become loose or damaged over time, which can cause them to squeak.
- Improper installation of brake pads: If brake pads are not installed properly, they can rub against the brake rotors and produce a squeaking noise.
- Foreign objects in the brake system: Foreign objects, such as dirt or gravel, can get into the brake system and cause the brakes to squeak.
If your car brakes are making a shriek sound, it is important to take action to prevent the problem from getting worse.
Why do some people find certain sounds, like nails on a chalkboard, to be shriek-inducing?
There are a few reasons why some people find certain sounds, like nails on a chalkboard, to be shriek-inducing.
- The sound is high-pitched and piercing. High-pitched sounds are more likely to be annoying or irritating than low-pitched sounds. This is because high-pitched sounds can cause the hair cells in the inner ear to vibrate more forcefully, which can be painful.
- The sound is unexpected or uncontrollable. When we hear a sudden or unexpected sound, it can startle us and cause us to react with fear or anxiety. This is because our brains are wired to be on the lookout for danger, and sudden sounds can be interpreted as a threat.
- The sound is associated with negative experiences. If we have had a negative experience in the past that was accompanied by a certain sound, we may become conditioned to associate that sound with the negative experience. This can make us react to the sound with fear or anxiety, even if the sound is not actually dangerous.
- The sound is a sign of pain or distress. Some sounds, such as the sound of a person crying or screaming in pain, can trigger our natural empathy and make us feel uncomfortable or distressed. This is because we are hardwired to respond to the suffering of others.
If you find certain sounds to be shriek-inducing, there are a few things you can do to cope:
- Avoid the sound. If possible, avoid the sound that you find triggering. This may mean avoiding certain places or activities.
- Wear earplugs or earmuffs. Earplugs or earmuffs can help to reduce the intensity of the sound.
- Take deep breaths. If you find yourself becoming anxious or stressed when you hear the sound, take some deep breaths to calm down.
- Talk to a therapist. If the sound is causing you significant distress, you may want to talk to a therapist. They can help you to develop coping mechanisms for dealing with the sound.
Can exposure to loud shriek sounds cause hearing damage?
Exposure to loud shriek sounds can cause hearing damage. Shriek sounds are typically very loud, and prolonged exposure to loud noise can damage the hair cells in the inner ear, which are responsible for hearing. This can lead to permanent hearing loss.
The amount of time it takes for loud noise to damage hearing depends on the loudness of the noise and the length of exposure. The louder the noise, the less time it takes to cause damage. For example, a noise that is 100 decibels (dB) can cause hearing loss in just a few minutes, while a noise that is 85 dB can cause hearing loss over the course of several years.
There are a few things you can do to protect your hearing from loud shriek sounds:
- Avoid loud noises. If you can, avoid situations where you will be exposed to loud noise. This may mean avoiding concerts, sporting events, and other activities where there is a lot of noise.
- Wear earplugs or earmuffs. Earplugs or earmuffs can help to reduce the intensity of the noise.
- Take breaks from loud noise. If you must be around loud noise, take breaks every 15 to 30 minutes to give your ears a rest.
- Get your hearing checked regularly. If you are concerned about your hearing, it is important to get your hearing checked regularly. This will help to detect any hearing loss early on, so that it can be treated.
It is important to remember that hearing loss is permanent. Once the hair cells in the inner ear are damaged, they cannot be repaired. Therefore, it is important to take steps to protect your hearing from loud noise.
Are there any medical conditions that can cause a person to make involuntary shriek sounds?
There are a number of medical conditions that can cause a person to make involuntary shriek sounds. Some of these conditions include:
- Tourette syndrome: Tourette syndrome is a neurological disorder that causes people to have tics, which are sudden, involuntary movements or sounds. Tics can be simple, such as blinking or clearing the throat, or they can be complex, such as making noises or repeating words. Shriek sounds are a type of complex tic that can occur in people with Tourette syndrome.
- Misophonia: Misophonia is a condition that causes people to have a strong negative reaction to certain sounds. These sounds can be anything from someone chewing to the sound of a ticking clock. People with misophonia may find that they are unable to control their reaction to these sounds, and they may make involuntary noises, such as shrieking, in response to them.
- Dementia: Dementia is a group of brain disorders that cause a decline in thinking, memory, and behavior. People with dementia may make involuntary sounds, such as shrieking, as a result of their cognitive decline.
- Parkinson’s disease: Parkinson’s disease is a neurological disorder that affects movement. People with Parkinson’s disease may make involuntary sounds, such as shrieking, as a result of their muscle contractions.
- Epilepsy: Epilepsy is a neurological disorder that causes seizures. People with epilepsy may make involuntary sounds, such as shrieking, during a seizure.
If you are concerned that you or someone you know may be making involuntary shriek sounds due to a medical condition, it is important to see a doctor for diagnosis and treatment.
The unmistakable shriek sound, often characterized by its sharp, piercing nature, can emanate from a variety of sources, both in industrial and household settings.
Whether it’s the result of malfunctioning machinery, plumbing issues, or even the high-pitched calls of certain pests, identifying and addressing these sounds is crucial for maintaining a peaceful and safe environment.
Employing a combination of engineering controls, regular maintenance, and soundproofing materials can go a long way in mitigating these disruptive noises, ensuring the comfort and well-being of those exposed to them.