Sound vs. noise
Sound, as a concept in physics, is defined as a wave disturbance in a gaseous, liquid or solid elastic medium (elastic waves) causing a subjective auditory sensation in humans or animals, or in psychology, a subjective auditory sensation caused by such a disturbance.
At the very least, noise is perceived as annoying sounds of excessive intensity to those around them, emitted over a long period of time, is defined as harmful to human health.
Environmental noise is defined by the World Health Organization (WHO) as harmful and persistent sounds generated by human activities.
Physical parameters describing sound
- Pitch
The unit of measurement for pitch is Herc [Hz], which specifies the number of vibrations per second.
1Hz = 1 vibration/second
Thus, the pitch is dependent on the frequency of vibration.
We can divide sound (tone) into:
- Audible to humans (sounds in the range of 16Hz to 20 thousand Hz)
- Low tone (bass) with frequencies of about 16-200 Hz,
- Mid tone with frequencies of about 200-3000 Hz,
- High tone (soprano) with frequencies of about 3000-10tys. Hz.
- Inaudible to humans
- Infrasound with frequencies lower than 16Hz,
- Ultrasound frequencies above 20,000 Hz.
- Sound volume
Sound pressure as a quantity expressed in Pascals [Pa] that describes the small changes in the air pressure in which sound propagates. Due to the very large range of sound pressures of sounds perceived by humans, a relative measure of sound pressure is used instead of sound pressure, which is the sound pressure level expressed in decibels [dB].
Since the decibel scale is logarithmic then an increase of every 3dB means a doubling of sound intensity. An example is the difference between an ordinary conversation (65dB) and a shout (80dB). 15dB produces 32 times the sound pressure.
Sound pressure, expressed in decibels, is referred to as sound intensity level or noise level.
|
Intensity [dB] |
Source |
|
10-20 |
The rustle of leaves |
|
30 |
Clock ticking |
|
40 |
Normal conversation |
|
50 |
Recommended by WHO |
|
50-60 |
The crowd of people |
|
70 |
Working vacuum cleaner, car on the move |
|
80 |
Trumpeting car, passing train |
|
100 |
Pneumatic hammer |
|
110 |
Motorcycle without a muffler |
|
160 |
Firecracker explosion |
|
190 |
Spacecraft launch |
- Sound color (acoustic spectrum)
A set of sound components (tones) of a certain frequency and amplitude, usually represented in the form of a graph, the distribution of harmonic vibration amplitudes as a function of vibration frequency.
Phenomena associated with sound
Acoustic background (measurement acoustic background) are all sounds that occur continuously at the measurement point during the noise test, which are not the test noise and are not acoustic interference.
Acoustic interference (unwanted sounds) are all sounds occurring accidentally during measurements, which, with properly conducted noise tests (in accordance with applicable standards), can and should be eliminated during measurements.
Noise is defined as a sound where rapid changes in its pitch and volume are not noticeable. Many types of noise are introduced such as white noise, pink noise, red noise, blue noise, among others.
The phenomenon of reverberation, commonly known as echo, is correlated with the duration of sound and occurs when the body stops vibrating and the sound continues to be heard. This happens because the resulting sound waves bounce off surfaces (such as walls or ceilings), and the human ear registers this as an apparent sound. This is a random phenomenon that finds its application in music, for example.
Origin of contamination
With regard to the sources of noise emissions, one can distinguish:
- Traffic noise, and includes:
- Road noise
- Railroad noise
- Aircraft noise
- Industrial noise;
- Everyday noise – defined as sounds that accompany people during daily activities, also called “social noise.”
Impact on health
Long-term exposure to noise can have health effects such as:
- Sleep disorders
Sleep is essential for the effective functioning of living organisms. Noise has the effect of shortening, or interrupting, sleep, which affects a person’s functioning during the day in the form of impaired concentration, reduced productivity and poor well-being. Long-term sleep disorders can lead to changes in metabolism, lack of appetite, memory consolidation disorders and cardiovascular problems.
- Cardiovascular effects
Exposure to noise has the effect of increasing stress levels, leading to increased blood pressure, altered heart rates or the release of unwanted hormones. These chronic effects can lead to premature mortality.
- Mental health effects, including anxiety, depression, irritability
Irritability, defined as a stress response that includes a range of negative feelings, is one of the most common reactions to noise. Long-term irritability can lead to mental health disorders or cardiovascular problems.
- Disorders of the metabolic system
- Hearing impairments
- Disorders of cognitive development in children
In the case of schooling, classroom noise affects lower motivation, impaired concentration and increased irritability in students. As a result, it leads to poorer academic performance and impaired learning.
