15.3 Effects of infrasound on humans and structures
2 min read•july 24, 2024
Infrasound, sound below 20 Hz, affects humans in unique ways. It can be heard, felt, and sensed through various body systems. While often unnoticed, infrasound can cause physical and psychological effects, from sleep disturbances to mood changes.
Buildings aren't immune to infrasound either. It can make structures vibrate, especially if the frequency matches the building's natural resonance. Factors like construction materials, distance from the source, and environmental conditions all play a role in how infrasound impacts buildings.
Human Perception and Health Effects of Infrasound
Human perception of infrasound
Top images from around the web for Human perception of infrasound
Frontiers | Motor and Predictive Processes in Auditory Beat and Rhythm Perception View original
Is this image relevant?
Auditory Pathways to the Brain – Introduction to Sensation and Perception View original
Is this image relevant?
Audition and Somatosensation | Anatomy and Physiology I View original
Is this image relevant?
Frontiers | Motor and Predictive Processes in Auditory Beat and Rhythm Perception View original
Is this image relevant?
Auditory Pathways to the Brain – Introduction to Sensation and Perception View original
Is this image relevant?
1 of 3
Top images from around the web for Human perception of infrasound
Frontiers | Motor and Predictive Processes in Auditory Beat and Rhythm Perception View original
Is this image relevant?
Auditory Pathways to the Brain – Introduction to Sensation and Perception View original
Is this image relevant?
Audition and Somatosensation | Anatomy and Physiology I View original
Is this image relevant?
Frontiers | Motor and Predictive Processes in Auditory Beat and Rhythm Perception View original
Is this image relevant?
Auditory Pathways to the Brain – Introduction to Sensation and Perception View original
Is this image relevant?
1 of 3
- Hearing threshold generally falls below 20 Hz varies among individuals depending on age and auditory health
- Perception mechanisms engage auditory system detects pressure fluctuations, tactile sensations felt through skin and internal organs, vestibular system senses motion and balance (inner ear)
- Common physiological effects manifest as pressure or fullness in ears similar to altitude changes, chest vibrations felt internally, feelings of awe or fear evoked by subliminal stimuli
- Factors affecting perception include sound pressure level measured in dB, exposure duration ranging from seconds to hours, individual sensitivity influenced by genetics and prior exposure
Health impacts of infrasound exposure
- Sleep disturbances disrupt circadian rhythms causing difficulty falling asleep and reduced sleep quality leading to daytime fatigue
- Cognitive effects impair mental processes decreasing concentration and task performance (reading, problem-solving)
- Cardiovascular impacts alter physiological functions changing heart rate and potentially affecting blood pressure regulation
- Psychological effects increase stress and levels induce mood changes (irritability, depression)
- Balance and spatial orientation issues arise from vestibular system disruption causing dizziness and
- Chronic fatigue develops over time due to cumulative effects of sleep disturbances and physiological stress
Infrasound Effects on Structures
Infrasound resonance in structures
- Natural frequencies of buildings typically fall within infrasound range dependent on height and construction materials (steel, concrete)
- Resonance phenomenon amplifies vibrations at specific frequencies transfers energy from to structural elements
- Structural responses manifest as swaying or oscillation in tall buildings (skyscrapers), rattling of windows and loose objects (picture frames, dishes)
- Potential damage mechanisms include fatigue stress on building materials weakening structural integrity over time through repeated flexing and vibration
Factors in infrasound vibration severity
- Source characteristics determine impact through frequency content of infrasound (1-20 Hz), sound pressure level measured in dB, duration of exposure from intermittent to continuous
- Structural properties influence susceptibility including natural frequency of the building, damping characteristics absorb vibrations, construction materials and methods (steel frame vs. masonry)
- Environmental factors affect transmission including ground composition and transmissibility (bedrock vs. sediment), presence of other structures in urban vs. rural settings
- Distance from infrasound source impacts intensity follows inverse square law
- Geometry and orientation of structure relative to source affects exposure surface area and angle
- Coupling efficiency between infrasound and structure determines energy transfer effectiveness varies with material properties and structural design
Key Terms to Review (18)
Acoustic Levitation: Acoustic levitation is a technique that uses intense sound waves to counteract the force of gravity, allowing small objects to be suspended in mid-air. This phenomenon occurs when the pressure variations created by sound waves create a standing wave pattern, producing regions of low and high pressure that can trap particles in a stable position. The principles behind acoustic levitation are connected to how sound waves interact with materials, and this has implications across various scientific and industrial applications.
Anxiety: Anxiety is a feeling of unease, such as worry or fear, that can be mild or severe. It often arises in response to stressors, including environmental factors, and can impact both mental and physical health. Understanding how anxiety relates to infrasound and environmental noise is crucial, as both can exacerbate anxiety symptoms, leading to increased stress levels and potential health issues.
Auditory masking: Auditory masking refers to the phenomenon where the perception of one sound is affected by the presence of another sound, making it harder to hear or distinguish the masked sound. This effect is critical for understanding how we perceive sound in noisy environments, and it connects to sound measurement, the impact of low-frequency sounds on humans and structures, and our ability to perceive pitch in relation to critical bands.
Decibel (dB): A decibel (dB) is a logarithmic unit used to measure the intensity of sound, expressing the ratio of a particular sound pressure level to a reference level. This measurement allows us to quantify how loud a sound is in relation to others, which is crucial when discussing the effects of infrasound on humans and structures. The scale is not linear; an increase of 10 dB represents a tenfold increase in intensity, making it a powerful tool for understanding sound levels that can impact our environment.
Disorientation: Disorientation refers to a state of mental confusion where an individual is unable to identify their location, time, or the situation they are in. This condition can occur due to various factors, including sensory overload or deprivation. In the context of infrasound, disorientation can be a significant psychological and physiological effect on humans, impacting their cognitive functions and overall well-being.
Field studies: Field studies refer to research conducted in real-world settings to gather data about specific phenomena, including the effects of infrasound on humans and structures. These studies help researchers observe and measure how infrasound interacts with various environments, providing valuable insights into its potential impacts on health and structural integrity. By collecting data directly from the field, researchers can better understand the real-life implications of infrasound exposure.
Headaches: Headaches are a common health issue characterized by pain or discomfort in the head, scalp, or neck. In the context of infrasound, headaches can arise as a response to low-frequency sound waves that humans may not consciously hear but can still affect their bodies, potentially leading to discomfort and various symptoms that impact daily life.
Hertz (Hz): Hertz (Hz) is a unit of frequency that measures the number of cycles per second of a periodic phenomenon, such as sound waves. In acoustics, Hertz is crucial for understanding the properties of sound, particularly when discussing infrasound, which refers to sound waves with frequencies below the lower limit of human hearing, typically below 20 Hz. The implications of infrasound on both human health and structural integrity are significant, making Hertz an essential concept in studying its effects.
Infrasound Waves: Infrasound waves are sound waves with frequencies below the range of human hearing, typically below 20 Hz. These low-frequency waves can travel long distances and penetrate various materials, making them significant in understanding their effects on both humans and structures. Infrasound can originate from natural sources like earthquakes and volcanic eruptions, as well as man-made sources such as machinery and explosions.
Laboratory experiments: Laboratory experiments are controlled investigations conducted in a dedicated setting where variables can be manipulated to observe their effects on subjects or systems. These experiments are essential for understanding complex phenomena, such as the effects of infrasound on humans and structures, as they provide a systematic approach to isolate and measure specific factors in a repeatable manner.
Man-made sources: Man-made sources refer to sounds generated by human activities or constructions that produce noise in the environment. These sources can range from industrial operations and transportation systems to construction activities and entertainment venues, significantly contributing to the overall soundscape, including low-frequency sounds such as infrasound, which can impact both humans and structures.
Material fatigue: Material fatigue refers to the progressive and localized structural damage that occurs when a material is subjected to cyclic loading, often leading to failure after a certain number of stress cycles. This phenomenon is crucial in understanding how structures respond to repeated stresses, particularly from sources like infrasound, which can cause vibrations that contribute to material degradation over time.
Natural phenomena: Natural phenomena are events or occurrences that happen in the natural world, typically without human intervention, and can be observed and studied scientifically. These phenomena encompass a wide range of activities, from weather events like storms to geological occurrences such as earthquakes, and even include biological processes. Understanding these events is crucial for comprehending how they interact with various aspects of life, including human health and structural integrity.
Nausea: Nausea is a feeling of unease or discomfort in the stomach that often leads to the urge to vomit. It can be triggered by various factors, including motion sickness, certain medical conditions, and exposure to infrasound. Understanding nausea is important, especially in relation to how low-frequency sounds can affect human health and well-being, as these sounds can cause physiological responses that manifest as this unpleasant sensation.
Seismic monitoring: Seismic monitoring refers to the process of observing and measuring seismic waves produced by earthquakes, explosions, or other ground movements. This practice helps in understanding the characteristics of these waves, which can inform us about their sources and impacts on structures and humans. It is crucial for assessing infrasound, as low-frequency sound waves from seismic events can affect both physical structures and human health.
Sound perception threshold: The sound perception threshold is the minimum level of sound intensity that a human can detect, serving as a baseline for hearing. This threshold varies among individuals and is influenced by factors such as age, health, and environmental conditions. Understanding this threshold is crucial when considering how infrasound affects human senses and structures, especially as low-frequency sounds can have profound effects below the audible range.
Subsonic frequencies: Subsonic frequencies refer to sound waves with frequencies below the range of human hearing, typically considered to be under 20 Hz. These frequencies can create significant physical effects and are often associated with infrasound, which can influence both human perception and structural integrity. Understanding subsonic frequencies is crucial as they may induce feelings of discomfort or unease in humans and can resonate with structures, potentially leading to damage or failure.
Vibration resonance: Vibration resonance occurs when a system vibrates at its natural frequency due to an external stimulus, causing it to amplify the oscillations. This phenomenon can lead to significant effects in various structures and living organisms, making it crucial to understand in contexts like infrasound, where low-frequency sound waves can resonate with physical and biological systems, potentially leading to adverse effects.