Acoustic Waves in Physics
An acoustic wave can simply be described as a longitudinal wave. A longitudinal wave is a wave that vibrates and moves in the direction of its propagation. This means the medium is either in the same or opposite direction of the way the wave travels. Acoustic waves are a form of Mechanical longitudinal waves; these waves are otherwise known as compression waves or compressional waves. Compressional waves obviously produce compression, decompression, and rarefaction to travel.
In Physics, the acoustic wave has an equation to describe the evolution of acoustic pressure and particle velocity as a function. The general equation is:
Acoustic waves have multiple equations, but this version is the simplified form. In a simplified acoustic wave equation there is only one spatial dimension. In other more complex equations there is a possibility of two or maybe even three dimensions. [5] The letter “p” in the general form equation pictured above is to show the acoustic pressure . The letter “c” represents the speed of sound. Both acoustic pressure and speed of sound are the key ingredients to describing the behavior of sound in matter.
A solution for this particular acoustic wave equation is:
“F” and “g” both show two twice-differentiable functions, and “c” again, is the speed of sound. [5]
After reading the first paragraphs you may be wondering why are acoustic waves so important in normal life or “why would I ever need this equation?’ Acoustic waves are important because sound is all around us. When you think of the word “acoustic” a few words may come to mind. Guitars, stereos, and many other items involve acoustic waves. For example, when the bass on a stereo is turned all the way up you m...
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...smits the waves from one direction but as soon as it reflects it blocks them from the other. [1]
Many people hear both terms, acoustic and sound waves and think they are basically the same. That seems to be untrue because sound waves do not have polarization. [3] The reason why they don’t have polarization is because sound waves oscillate in the same directions they move. This means sound waves cannot reflect while acoustic waves can. For example, when you are in a domed shaped building the acoustics allow you to hear an echo or a projection of a noise from the other side of the room.
There is not many information on acoustic waves but it was interesting researching this topic. The little that I found was really cool and I’m glad I did this essay on such a topic. Acoustic waves are all around us and are important in science.
The purpose of this experiment was to determine whether if the sound is affected when it travels through different length pipes. The method used to do this experiment was created by using 5 different PVC pipes in the lengths of 10, 20, 30, 40, and 50 centimeters. Then, using a tuning fork, sound will be produced on one end of the PVC pipe and measured with a decimeter on the other end. This experiment was recorded using 5 trials for each independent level and the average decibels (dB) for each pipe length were recorded.
If you put your finger gently on a loudspeaker you will feel it vibrate - if it is playing a low note loudly you can see it moving. When it moves forwards, it compresses the air next to it, which raises its pressure. Some of this air flows outwards, compressing the next layer of air. The disturbance in the air spreads out as a travelling sound wave. Ultimately this sound wave causes a very tiny vibration in your eardrum - but that's another story.
waves were reflected back to the transducer as they crossed interfaces of different acoustic impedance. More simply, the ultrasound bounced off the
A longitudinal wave on the other hand is where the particles of the medium move in the same direction as the wave. Energy is passed along the air molecules through the lengthway vibrations of a longitudinal wave. This process continues throughout the entire wave, and t...
...ype of chain reaction. The pressure wave consists of what is known as compressions and rarefactions. The compression parts are areas of high pressure, where the air molecules are compressed into a small space. On the other hand, the rarefactions are areas of low pressure, where the air molecules are spread out. The result of the compressions and rarefactions is a longitudinal sound wave (Henderson).
Ultrasound is sound waves that have a frequency above human audible. (Ultrasound Physics and Instrument 111). With a shorter wavelength than audible sound, these waves can be directed into a narrow beam that is used in imaging soft tissues. As with audible sound waves, ultrasound waves must have a medium in which to travel and are subject to interference. In addition, much like light rays, they can be reflected, refracted, and focused.
Sound is a type of longitudinal wave that originates as the vibration of a medium (such as a person’s vocal cords or a guitar string) and travels through gases, liquids, and elastic solids as variations of pressure and density. The loudness of a sound perceived by the ear depends on the amplitude of the sound wave and is measured in decibel, while its pitch depends on it frequency measured in hertz, (Shipman-Wilson-Higgins, 2013).
Sounds are produced by the vibrations of material objects, and travel as a result of
The vibration of the strings of a guitar causes the sound wave, but is not actually what you are hearing. The amplification of the sound wave is what is actually heard. The differences in the tension of the stings and the mass of the strings affect the pitch of the sound produced. The ends of each string are nodes, or where the wave does not travel from its initial position. The note you hear from the string is actually the first harmonic of the wave; other harmonics created when plucking a string form the undertones and overtones of a note. The waves on a guitar string are transverse waves, meaning they travel perpendicular to the original position. The waves are also standing waves, because they remain in the same position.
... middle of paper ... ... Designs, C. & B. 2013. ProSonic Acoustic Cubes -. [online] Available at: http://www.customaudiodesigns.co.uk/acoustic-cubes.htm [Accessed: 1 Dec 2013].
Sound is essentially a wave produced by a vibrating source. This compression and rarefaction of matter will transfer to the surrounding particles, for instance air molecules. Rhythmic variations in air pressure are therefore created which are detected by the ear and perceived as sound. The frequency of a sound wave is the number of these oscillations that passes through a given point each second. It is the compression of the medium particles that actually constitute a sound wave, and which classifies it as longitudinal. As opposed to transverse waves (eg. light waves), in which case the particles move perpendicular to the direction of the wave movement, the medium particles are moving in the same or opposite direction as the wave (Russell, D. A., 1998).
Sound does however perform much more important, intricate and complex functions than commonly accepted. Sound combines with moving pictures in various ways to create meaning but is diverse and has numerous other uses.