Sound is a sequence of waves of pressure which propagates through compressible media such as air or water. During their propagation, waves can be reflected, refracted, or attentuated by the medium. The purpose of this experiment is to examine what effect the characteristics of the medium have on sound.
Ground Wave or Surface Wave Propagation
A ground wave travels along the surface of the earth. These waves are vertically polarized. So, vertical antennas are useful for these waves. If a horizontally polarized wave is propagated as a ground wave, due to the conductivity of the earth, the electric field of the wave gets short-circuited. As the ground wave travels away from the transmitting antenna it gets attenuated. To minimize this loss the transmission path must be over the ground with high conductivity. With respect to this condition, sea water should be the best conductor but it was observed that large storage of water in ponds, sandy or rocky Soil shows maximum losses. Hence, high power low-frequency transmitters, using ground wave propagations, are preferably located on ocean fronts. As ground losses increase rapidly with frequency, this propagation is used practically for signals up to frequency 2 MHz only.
Sky Wave Propagation
Every long radio Communication of medium and high frequencies are conducted using skywave propagation. In this mode reflection of EM waves from the ionized region in the upper part of the Atmosphere of the earth is used for transmission of waves to longer distances. This part of the atmosphere is called ionosphere which is at about 70-400 km height. Ionosphere reflects back the EM waves if the frequency is between 2 to 30 MHz’s. Hence, this mode of propagation is also called as Short wave propagation. Using sky wave propagation point to point communication over long distances is possible. With the multiple reflections of sky waves, global communication over extremely long distances is possible.
Space Wave Propagation
When we are dealing with EM waves of frequency between 30 MHz to 300 MHz, then space wave propagation is useful. Here properties of Troposphere are used for transmission. When operating in space wave propagation mode, the wave reaches the receiving antenna directly from the transmitter or after reflection from troposphere which is present at about 16km above the earth surface. Hence space wave mode consists of two components .i.e. direct wave and indirect wave.
Short wave broadcasting usually takes place in the frequency range of 1.7 – 30 MHz. As we have seen above the frequencies in this range are propagated through Skywave propagation mode. Depending on the frequency or wavelength the Electromagnetic Waves produce different affected in various materials and devices. Hence, the different parts of the electromagnetic spectrum are utilized for various applications.
Audible and Inaudible sound
Whenever an object vibrates ,sound is produced. When a simple pendulum vibrates, a sound is produced. But the sound produced by a vibrating simple pendulum is not heard by us. This is because the frequency of vibration of a simple pendulum is very low. It may be 2 or 3 hertz only.And our ears cannot hear sounds of such low frequencies. It is an inaudible sound which cannot be heard by us. An object must vibrate at the rate of at least 20 times per second to be able to produce audible sound.
The sounds having too low frequencies which cannot be heard by human ear are called infrasonic sounds. Rhinoceros can produce infrasonic sounds having frequency less than 20 hertz. They can also hear infrasonic sounds.
The human ear can hear sounds which have frequencies between 20 hertz and 20,000 hertz. The lower limit of frequency of human hearing is 20 Hertz and upper limit of human hearing is 20000 Hz. The sounds having too high frequency which cannot be heard by human ear are called ultrasonic sounds. The sounds of frequency greater than 20,000 hertz are called ultrasonic. The ultrasonic sounds cannot be heard by human beings.
The human beings can neither produce ultrasonic sound nor can they hear ultrasonic sounds.But there are some animal which can produce ultrasonic sounds as well as hear ultrasonic sound.
Noise and Music
The distinction between music and noise is mathematical form. Music is ordered sound. Noise is disordered sound. Music and noise are both mixtures of sound waves of different frequencies. The component frequencies of music are discrete (separable) and rational (their ratios form simple FRACTIONS) with a discernible dominant frequency. The component frequencies of noise are continuous (every frequency will be present over some range) and random (described by a Probability distribution) with no discernible dominant frequency.
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Sound is a form of energy that travels in waves. It can travel through solids, liquids, and gases. The speed of sound depends on the medium through which it is traveling. Sound travels fastest in solids, then liquids, and slowest in gases.
Audible sound is sound that can be heard by humans. The range of human hearing is from about 20 Hz to 20 kHz. Sound waves with frequencies below 20 Hz are called infrasound, and sound waves with frequencies above 20 kHz are called ultrasound.
Inaudible sound can be harmful to humans. Infrasound can cause nausea, vomiting, and headaches. Ultrasound can cause damage to the eardrum and other parts of the inner ear.
Noise is unwanted or unpleasant sound. Noise can be caused by many things, such as traffic, construction, and machinery. Noise can be harmful to humans. It can cause Stress, anxiety, and hearing loss.
Music is sound that is pleasing to the ear. Music is made up of tones, which are sounds of different frequencies. Tones can be combined to create chords, which are groups of three or more tones. Chords can be combined to create melodies, which are sequences of tones that follow a particular pattern.
Music has many benefits for humans. It can improve mood, reduce stress, and boost the immune system. Music can also help to improve cognitive function and memory.
Sound is a powerful force that can have a significant impact on our lives. It is important to understand the nature of sound and its effects on us so that we can use it wisely.
Medium of Propagation
Sound can travel through three different States of Matter: solids, liquids, and gases. The speed of sound depends on the medium through which it is traveling. Sound travels fastest in solids, then liquids, and slowest in gases.
In solids, sound travels in the form of compression waves. These waves are caused by the vibration of the atoms in the solid. The atoms vibrate back and forth, causing the neighboring atoms to vibrate as well. This vibration travels through the solid in the form of a wave.
In liquids, sound travels in the form of compression waves as well. However, the waves are not as strong as they are in solids. This is because the Molecules in liquids are not as close together as the atoms in solids. As a result, the waves are not able to transfer as much energy as they are in solids.
In gases, sound travels in the form of compression waves as well. However, the waves are even weaker than they are in liquids. This is because the molecules in gases are very far apart. As a result, the waves are not able to transfer any energy at all.
Audible and Inaudible Sound
Audible sound is sound that can be heard by humans. The range of human hearing is from about 20 Hz to 20 kHz. Sound waves with frequencies below 20 Hz are called infrasound, and sound waves with frequencies above 20 kHz are called ultrasound.
Infrasound is sound that has a frequency below 20 Hz. It is produced by many natural phenomena, such as Earthquakes, Volcanoes-2/”>Volcanoes, and wind. Infrasound can also be produced by man-made sources, such as large machinery and jet engines.
Ultrasound is sound that has a frequency above 20 kHz. It is used in many medical applications, such as ultrasound imaging and ultrasound therapy. Ultrasound can also be used to clean surfaces and to detect flaws in materials.
Noise and Music
Noise is unwanted or unpleasant sound. Noise can be caused by many things, such as traffic, construction, and machinery. Noise can be harmful to humans. It can cause stress, anxiety, and hearing loss.
Music is sound that is pleasing to the ear. Music is made up of tones, which are sounds of different frequencies. Tones can be combined to create chords, which are groups of three or more tones. Chords can be combined to create melodies, which are sequences of tones that follow a particular pattern.
Music has many benefits for humans. It can improve mood, reduce stress, and boost the immune system. Music can also help to improve cognitive function and memory.
Conclusion
Sound is a powerful force that can have a significant impact on our lives. It is important to understand the nature of sound and its effects on us so that we can use it wisely.
What is sound?
Sound is a form of energy that travels in waves. It is produced when an object vibrates, causing the air molecules around it to vibrate as well. These vibrations travel through the air until they reach our ears, where they are converted into electrical signals that our brains interpret as sound.
What is the medium of propagation of sound?
Sound can travel through any medium that has molecules, such as air, water, or solids. The speed of sound depends on the density of the medium. Sound travels fastest through solids, followed by liquids, and then gases.
What is audible sound?
Audible sound is sound that can be heard by humans. The range of human hearing is from about 20 Hz to 20 kHz. Sound waves with frequencies below 20 Hz are called infrasound, and sound waves with frequencies above 20 kHz are called ultrasound.
What is inaudible sound?
Inaudible sound is sound that cannot be heard by humans. This includes infrasound and ultrasound. Infrasound can be produced by earthquakes, volcanoes, and even some animals. Ultrasound is used in medical imaging and in some types of communication.
What is noise?
Noise is unwanted sound. It can be caused by a variety of sources, such as traffic, construction, and machinery. Noise can be harmful to our Health, both physically and mentally. It can cause hearing loss, stress, and sleep problems.
What is music?
Music is a form of art that uses sound to create a pleasing effect. It is often used to express emotions, tell stories, and create a sense of atmosphere. Music can be made with a variety of instruments, including the human voice.
What is the difference between noise and music?
Noise is unwanted sound, while music is a form of art that uses sound to create a pleasing effect. Noise can be harmful to our health, both physically and mentally, while music can have a positive effect on our health.
- Sound is a form of energy that travels in waves. It can travel through solids, liquids, and gases. True or False?
- The speed of sound is different in different materials. True or False?
- The frequency of a sound wave determines its pitch. True or False?
- The amplitude of a sound wave determines its loudness. True or False?
- When two sound waves meet, they can interfere with each other. True or False?
- Constructive interference occurs when two waves meet in phase. True or False?
- Destructive interference occurs when two waves meet out of phase. True or False?
- Echoes are caused by sound waves reflecting off of a surface. True or False?
- The Doppler effect is the change in the frequency of a sound wave as the source of the sound or the observer moves. True or False?
- Infrasound is sound with a frequency below 20 Hz. True or False?
- Ultrasound is sound with a frequency above 20 kHz. True or False?
- White noise is a sound that contains all frequencies at equal intensity. True or False?
- Pink noise is a sound that contains frequencies that decrease in intensity with increasing frequency. True or False?
- Brown noise is a sound that contains frequencies that increase in intensity with increasing frequency. True or False?
- Music is a form of sound that is organized in a way that is pleasing to the ear. True or False?
- Noise is unwanted sound. True or False?
- Sound can be used to carry information. True or False?
- Sound can be used to control machines. True or False?
- Sound can be used to create art. True or False?
- Sound can be used to heal. True or False?