Increased

Atmospheric

Pressure Decreased

Sound wave

Pressure

Pressure

Propagation of

sound

Motion of air molecules

associated wim sound.

speed of the sound propagation C = 344 m/sec, t = 20⁰C

The physical characteristics of the sound wave

• Sound pressure, P, N/m² - Pa

• Sound energy, I, W/cm²

Not all mechanical vibrations can be perceived by the human ear.

• The vibrations have to be of a certain magnitude to be audible

• The frequency has to be within certain limit

10

210^? 2^10²

N/fll* I 2

Sound pressure, N/m² = Pa

«T*

iff

ur*

₁₀-16

0.02 OJB 0.1 02 a5 1 2 5 10 20

16 r'ecje^.cv fn kHz - -20 000

Frequency, Hz

-2

Sound energy, :^e

⁷ic" 2^10^-5

W/cm²

Sound pressure level, L, Decibel

p

Weber-Fechner law: S=k*lgI

Sound pressure level

L = 10lg— = 20 lg ^P

I

o

o

, dB

Noise is an unwanted sound

The main sources of noise are

• Transport

• Industrial equipment

• Home appliances

• Musical instruments

• People

• Nature sounds

ealth effects from noise

The somatosensory system

• is a diverse sensory system comprising the receptors and processing centers to produce the sensory modalities such as

• touch,

• temperature

• proprioception (body position),

• and nociception (pain).

The sensory receptors cover

the skin and epithelia, skeletal muscles, bones,

internal organs, and the cardiovascular system.

Self-study task, topic 3.

The main function of the somatosensory system

• touch

• temperature

• proprioception,

• and nociception

Taste: the principle elements of sensory system smell: the principle elements of sensory system

Lecture 4-5 Technogenic hazards. Radiation safety

1. Nature of Radioactivity. Ionizing radiation

2. Assessment Criteria

3. The main sources of the Ionizing Radiation

4. Radiation damages : biological effects

5. Radiation Protection

H

1. Nature of radioactivity. Ionizing radiation iRadiation is a form of energy I

r

Scientists classify most forms of energy as either potential energy or kinetic energy

• Kinetic energy is the energy that matter has because of its motion and mass

• moving car *flow of water * charged particles

• Potential energy is the energy stored in object as a result of the position of its parts

• a stick of dynamite,

• still water behind a dam,

• the nuclear energy stored in the atoms

Non-ionizing radiation

Low-energy radiation: radiation that does not have energy enough to ionize atoms.

Non-Ionizing Radiation

* *

Radio Waves Infrared Light

Levels of matter's organization

Subatomic level

Atomic+ level

Atoms

Biosphere

Molecule

Community

Body

system

Organ

Organism

Population