Concepts of ultrasound physics

The steps shown in the above diagram can be found in any acoustical event or process. There are many kinds of cause, both natural and volitional. There are many kinds of transduction process that convert energy from some other form into sonic energy, producing a sound wave. There is one fundamental equation that describes sound wave propagation, the acoustic wave equationbut the phenomena that emerge from it are varied and often complex.

Concepts of ultrasound physics

The Human Ear A sound wave, like any other wave, is introduced into a medium by a vibrating object. The vibrating object is the source of the disturbance that moves through the medium.

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The vibrating object that creates the disturbance could be the vocal cords of a person, Concepts of ultrasound physics vibrating string and sound board of a guitar or violin, the vibrating tines of a tuning fork, or the vibrating diaphragm of a radio speaker. Regardless of what vibrating object is creating the sound wave, the particles of the medium through which the sound moves is vibrating in a back and forth motion at a given frequency.

The frequency of a wave refers to how often the particles of the medium vibrate when a wave passes through the medium. The frequency of a wave is measured as the number of complete back-and-forth vibrations of a particle of the medium per unit of time.

If a particle of air undergoes longitudinal vibrations in 2 seconds, then the frequency of the wave would be vibrations per second.

This is sensible since each particle vibrates due to the motion of its nearest neighbor. The first particle of the medium begins vibrating, at say Hz, and begins to set the second particle into vibrational motion at the same frequency of Hz.

The second particle begins vibrating at Hz and thus sets the third particle of the medium into vibrational motion at Hz. The process continues throughout the medium; each particle vibrates at the same frequency.

Concepts of ultrasound physics

And of course the frequency at which each particle vibrates is the same as the frequency of the original source of the sound wave.

Subsequently, a guitar string vibrating at Hz will set the air particles in the room vibrating at the same frequency of Hz, which carries a sound signal to the ear of a listener, which is detected as a Hz sound wave. The back-and-forth vibrational motion of the particles of the medium would not be the only observable phenomenon occurring at a given frequency.

Since a sound wave is a pressure wavea detector could be used to detect oscillations in pressure from a high pressure to a low pressure and back to a high pressure. As the compressions high pressure and rarefactions low pressure move through the medium, they would reach the detector at a given frequency.

For example, a compression would reach the detector times per second if the frequency of the wave were Hz. Similarly, a rarefaction would reach the detector times per second if the frequency of the wave were Hz.

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The frequency of a sound wave not only refers to the number of back-and-forth vibrations of the particles per unit of time, but also refers to the number of compressions or rarefactions that pass a given point per unit of time.

A detector could be used to detect the frequency of these pressure oscillations over a given period of time. The typical output provided by such a detector is a pressure-time plot as shown below. Since a pressure-time plot shows the fluctuations in pressure over time, the period of the sound wave can be found by measuring the time between successive high pressure points corresponding to the compressions or the time between successive low pressure points corresponding to the rarefactions.

As discussed in an earlier unitthe frequency is simply the reciprocal of the period. For this reason, a sound wave with a high frequency would correspond to a pressure time plot with a small period - that is, a plot corresponding to a small amount of time between successive high pressure points.

Conversely, a sound wave with a low frequency would correspond to a pressure time plot with a large period - that is, a plot corresponding to a large amount of time between successive high pressure points. The diagram below shows two pressure-time plots, one corresponding to a high frequency and the other to a low frequency.

Frequency, Pitch and Human Perception The ears of a human and other animals are sensitive detectors capable of detecting the fluctuations in air pressure that impinge upon the eardrum. For now, it is sufficient to say that the human ear is capable of detecting sound waves with a wide range of frequencies, ranging between approximately 20 Hz to 20 Hz.

Any sound with a frequency below the audible range of hearing i.

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Humans are not alone in their ability to detect a wide range of frequencies. Dogs can detect frequencies as low as approximately 50 Hz and as high as 45 Hz.

Cats can detect frequencies as low as approximately 45 Hz and as high as 85 Hz. Bats, being nocturnal creature, must rely on sound echolocation for navigation and hunting. Bats can detect frequencies as high as Hz.Comprehensive Review for the MCAT Physics Organized by Officially Tested Topics.

Concepts of ultrasound physics

Comprehensive Review for the MCAT Physics Organized by Officially Tested Topics. Gulfcoast Ultrasound Institute. Click on our logo to go to our new homepage. Go directly to one of our specialties. Abdominal.

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A sound wave, like any other wave, is introduced into a medium by a vibrating object. The vibrating object is the source of the disturbance that moves through the medium. Acoustics is the branch of physics that deals with the study of all mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound.A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical torosgazete.com application of acoustics .

Acoustics is the branch of physics that deals with the study of all mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound.A scientist who works in the field of acoustics is an acoustician while someone working in the field of acoustics technology may be called an acoustical torosgazete.com application of acoustics is present in almost.

Pitch and Frequency