# Sound Waves

## Sound waves are a mechanical oscillation of pressure. It is a series of vibrations that can be heard.

Frequency

### What happens to the intensity of the received sound when a surface receiving sound is moved from its original position to a position three times farther away from the source of the sound?

It will be 1/9 as intense (or badly phrased, "nine times lower"). Intensity is defined as the energy crossing per unit area in unit time. So intensity will be inversely proportional to the square of the distance. So as distance is multiplied by 3 times then intensity would be reduced by 3² i.e. 9 times. (A meter reveals that the sound level has dropped by 9.54 dB.) For sound intensity (acoustic intensity) we use in the free field (direct field) the inverse square law = 1/r². I1 and r1 belong to the close distance and I2 and r2 belong to the far distance. I2 = I1 * (r1/r2)² I2 = I1 * (1/3)² = (I/ 9) *Do not forget that the sound pressure is not the same as sound intensity. Sound pressure needs the distance law 1/r. (No square at all). For sound pressure we use in the free field (direct field) the inverse distance law = 1/r. p1 and r1 belong to the close distance and p2 and p2 belong to the far distance. p2 = p1 x r1/r2 p2 = p1 x 1/3 = p1 / 3 Three times farther away gives one third the sound pressure of the close sound pressure. For sound intensity (acoustic intensity) we use in the free field (direct field) the inverse square law = 1/r². I1 and r1 belong to the close distance and I2 and r2 belong to the far distance. I2 = I1 x (r1/r2)² I2 = I1 x (1/3)² = I1 / 9 Three times farther away gives one ninth the sound intensity of the close sound intensity. Scroll down to related links and look at "Sound pressure p and the inverse distance law 1/r". For sound intensity (acoustic intensity) we use in the free field (direct field) the inverse square law = 1/r². I1 and r1 belong to the close distance and I2 and r2 belong to the far distance. I2 = I1 * (r1/r2)² I2 = I1 * (1/3)² = I1 / 9 Three times farther away gives one ninth the sound intensity of the close sound intensity. Do not forget that the sound pressure is not the same as sound intensity. Sound pressure needs the distance law 1/r. (No square at all). For sound intensity (acoustic intensity) we use in the free field (direct field) the inverse square law = 1/r². I1 and r1 belong to the close distance and I2 and r2 belong to the far distance. I2 = I1 x (r1/r2)² I2 = I1 x (1/3)² = I1 / 9 Three times farther away gives one ninth the sound intensity of the close sound intensity. For sound pressure we use in the free field (direct field) the inverse distance law = 1/r. p1 and r1 belong to the close distance and p2 and p2 belong to the far distance. p2 = p1 x r1/r2 p2 = p1x 1/3 = p1 / 3 Three times farther away gives one third the sound pressure of the close sound pressure. Scroll down to related links and look at "Sound pressure p and the inverse distance law 1/r". For sound intensity (acoustic intensity) we use in the free field (direct field) the inverse square law = 1/r². I1 and r1 belong to the close distance and I2 and r2 belong to the far distance. I2 = I1 x (r1/r2)² I2 = I1 x (1/3)² = I1 / 9 Three times farther away gives one ninth the sound intensity of the close sound intensity. For sound pressure we use in the free field (direct field) the inverse distance law = 1/r. p1 and r1 belong to the close distance and p2 and p2 belong to the far distance. p2 = p1 x r1/r2 p2 = p1 x 1/3 = p1 / 3 Three times farther away gives one third the sound pressure of the close sound pressure. Scroll down to related links and look at "Sound pressure p and the inverse distance law 1/r". For sound intensity (acoustic intensity) we use in the free field (direct field) the inverse square law = 1/r². I1 and r1 belong to the close distance and I2 and r2 belong to the far distance. I2 = I1 * (r1/r2)² I2 = I1 * (1/3)² = I1 / 9 Three times farther away gives one ninth the sound intensity of the close sound intensity. For sound pressure we use in the free field (direct field) the inverse distance law = 1/r. p1 and r1 belong to the close distance and p2 and p2 belong to the far distance. p2 = p1 * r1/r2 p2 = p1 * 1/3 = p1 / 3 Three times farther away gives one third the sound pressure of the close sound pressure. Scroll down to related links and look at "Sound pressure p and the inverse distance law 1/r".

### What are the uses of multiple reflection of sound?

1) Megaphones and musical instrumentsà Megaphones or loudhailers, horns, musical instruments are all designed to send sound in a particular direction without spreading it in all directions. In these instruments, a tube followed by a conical opening reflects sounds successively to guide most of the sound waves from the source in the forward direction. 2) Stethoscopeà In stethoscope the sound of a patient's heartbeat is guided by along the tube of the stethoscope to the doctor's ears by multiple reflections of sound. 3) Curved ceilingsà the ceilings of a concert halls, conference halls and cinema halls are made curved so that sound after reflection reaches all the corners of the halls. 4) Sound boardsà in large halls or auditorium, large concave wooden boards are placed behind the speaker. The speaker stands at the focus of this concave reflecting surface. After reflection the sound is spread evenly towards the audience. This makes the sound readily available even at a distance.

### How can you compare electromagnetic waves to sound waves?

The clearest difference is in their speeds. Sound travels around 720 miles an hour at sea level. Light travels at 186,000 miles per second. That is it goes a foot in about a picosecond. Sound will go a foot in about one milisecond. Sound needs a medium like air or water to travel and is greatly effected by the medium. Light travels without much regard for its' medium or the lack of one. It is effected when going through glass and crystals. Light will bend and even separate into its constituent colors. Sound is produced mechanically. Light is caused by the electron activity in an atom. It can be mechanically generated but is an electronic activity. Sound occurs when molecules are excited by a repeated mechanical action. A speaker cone moving back and forth causes air pressure variations that our ear gathers and starts translating it into something our brains can deal with. Light happens when the atoms valence electrons are made to jump into a higher orbit and when they fall back down they give off a photon. It is light in a confusing quantum package that has the properties of both having mass and being an electromagnetic wave.

### What name is given to the reflected sound waves in a cave or an empty hall?

what is the name given to the reflected sound waves in a cave or an empty hall

### Is radiant energy the same as sound waves?

Radiant energy is a term that is almost exclusively used for electromagnetic energy. When something is hot, it emits radiant energy. The sun is an obvious example, but all object actually emit radiant energy. The hotter the object, the more energy. Sound does carry energy, but it is not electromagnetic. Objects can emit sound and even "radiate" sound, but the term radiant energy is not normally used for sound.

### What is sound energy?

Sound waves have energy. The energy in a sound wave is both kinetic and potential energy. Read below for the details. This answer refers to the simplest form of sound, sound in air. There is also sound in liquid and solid materials where the details get more complicated. Sound is vibration in air, regions of air being compressed and rarefied as the sound wave propagates. Just as in a vibrating spring, the medium has mass and moves and so moving mass is kinetic energy. Just as in the spring there is compression and rarefaction, so there is elastic potential energy. It takes energy to create the compressed regions and they the compressed regions return that energy when they expand. In fact, one can show that these two are equal in a sound wave, potential energy = kinetic energy, just like a spring. Just like in a vibrating spring, the total energy is constant and equal to the average kinetic energy plus the average potential energy.

### Why wouldn't you be able to hear someone speak in outer space?

Sound needs matter to pass through to distribute the waves. There is no matter in the vacuum of space for a sound wave to travel through, so you can't hear anything in space.

the pinna

### What happens when two sound waves collide?

They collide and travel together, producing high crests and deep troughs. This is called "constructive inference". If the crests align with troughs and troughs with crests, "destructive inference" occurs. The waves are now "out of phase" and their wave heights are subtracted from one another, producing smalls crests and troughs or even briefly cancelling out the waves completely. Sound waves don't interact much with each other at all. The constructive and destructive interference mentioned above will be percieved by your ears or a microphone though. You can't effectively cancel two sound waves by shooting them at each other.

### What animals use infrasound?

African Elephants for communication

### How can I fix my built in mic on my desktop?

When you say "fix" does that mean it used to work at some point and then it stopped working all of a sudden? This can be due to a recent upgrade. Maybe you upgraded to Windows 10, which in such case it's common to run into such internal mic issues. There are three things you can try: 1. Update all driver: The issue may be due to some conflict with the drivers. You can update manually or download and install a software called "driver easy." The driver easy automatically recognizes your windows version and will install the best drivers for it. It's easy to use as well. 2. Also, you can try setting your mic as the default. In some cases, this helps. All you need to do is right-click on the speaker icon at the bottom right, select "recording devices," then in the sound dialog, click the recording tab and select your mic as default.

### Application of ultrasonics?

The ultrasonics used in various applications like in Industrial , medical ,etc. # INDUSTRIAL APPLICATION: 1. ultrasonics are used for soldering and drilling purposes . 2. ultrasonics are used for cutting and welding purposes also . 3. ultrasonics are used to emulsify immiscible liquids like mercury and water. 4. ultrasonics are used for cleaning of tiny objects like watches etc ., 5. ultrasonics are also used in the sterilization of water and milk. #MEDICAL APPLICATION 1.Ultrasonics waves are used for relieving neuralgic and rheumatic pain . 2.Ultrasonics waves are used to destroy dangerous tissues in the human bodies . 3. Ultrasonics are used in extraction of broken teeth without pain . 4. Ultrasonics waves are used to find the velocity of blood flow and the movement of heart in human body also .

### Does sound travel in a straight line?

sound yes sound travel in a straight line What Sound Looks Like The answer is yes and no. If you drew a line from the source of a sound to where you were when you perceived it, it would appear to be a line. However, upon further analysis (the depth of that depending on the sound you are looking at), you would see that it actually travels in a wave form, having an amplitude, frequency, wave length, period and speed. Does sound travel in a straight line? No, sound travels in a wave, therefore it does not travel in a straight line. It does travel in a line, just not a staright one

### What does 'the frequency of a sound wave mean?

It means, how many vibrations per second are there. It means, how many vibrations per second are there. It means, how many vibrations per second are there. It means, how many vibrations per second are there.

### Is there sound in space?

No, there is no sound in space because there is no air. Without air sound will not travel anywhere. Sound is created by a wave moving. For a wave to move, it needs a medium. Sound travels in air or water. There is no air or water in the vacuum of space. Believe it or not...this is actually false. An amazingly sensitive microphone, in a sense, was used to discover the constant B-flat coming from a black hole. (This found on NASA's website. Based on research from NASA's Chandra X-ray Observatory." This comes from the Space.com website... "Sound can travel through space, because space is not the total vacuum it's often made out to be. Atoms of gas give the universe a ubiquitous atmosphere of sorts, albeit a very thin one. Sound, unlike light, travels by compressing a medium. On Earth, the atmosphere works well as a sound-carrying medium, as does water. The planet itself is very adept at transmitting an earthquake's seismic waves, a form of sound. Space, though not as efficient, can also serve as a medium. If a brave and clever astronaut could safely remove her helmet and shout into the cosmos, her voice would carry." Also do keep in mind that actually their are tons of particles in space. Just not near as many parts per million as here on Earth. As a matter of fact NASA has even released such research on this to attempt to solve a problem with near light speed travel. Hydrogen atoms would bombard the front of the craft at high rates of speed. Essentially such a collision of particles would break up the vehicle in a short amount of time. This alone proves space isn't a pure void. Besides...their is nothing to force all the molecules in the universe to stay attached to everything. Therefore it only seems logical to assume some do escape into the "void" we know as space.

### What measurement do we use to measure loudness?

The unit of measurement for loudness is in decibels. Human hearing damage/lose can be sustained by long or repeated exposure to levels above 85dB.

### What unit is a wave's velocity measured in?

the distance.... ....over time. In Metres/second.

### What are sound waves?

sound waves are the vibrations that occur in a material as a sound passes through it.

### How does the frequency affect the sound made by soundwaves?

The frequency of a sound wave affects the pitch of the sound. If the frequency of a wave increases causing more waves for every second, the pitch will go up, and vice-versa.

### What are some industrial applications of ultrasonics?

CLEANING Cleaning was one of the earliest industrial applications of ultrasonics. Objects to be cleaned are placed in a bath of fluid which is violently agitated by a number of ultrasonic transducers. The fluid may be water or solvent based, depending on the application. Traditionally the transducers were fitted around the walls of the cleaning bath, but some modern equipment uses an external transducer attached to a resonant probe which transmits the vibrations to the fluid. The ultrasonics may affect the cleaning process in several ways. Rapid movement in the fluid can help to de-wet surfaces, overcoming surface tension, and may also help to dislodge dirt particles and carry them away from the surface. Cavitation is probably the most interesting (and potent) effect - the shock waves generated by tiny implosions of vapour bubbles can be devastating at close range. The bubbles are so tiny that they can penetrate even the smallest crevices, making the process ideal for parts which could not be cleaned by other methods. Note also that the process must be well controlled to minimise erosion of the surfaces of the parts being cleaned. The standard test of ultrasonic intensity in a cleaning bath is to immerse a standard foil strip for a set time, then remove it and count the number of holes. CUTTING Imagine a knife which moves itself backwards and forwards in a sawing action, thirty thousand times a second. True the distance moved is very small but the acceleration is so high that nothing can move with the blade or stick to it. Ultrasonic scalpels are used by surgeons where they want to cut without exerting any pressure. In industry ultrasonic cutting tools are used for products that are difficult to cut by other means. The heat generated by the ultrasonic vibrations can also be useful. Some man-made fabrics are cut and simultaneously sealed using ultrasonic knives to prevent fraying. ULTRASONIC MACHINING Ultrasonics have been used in several ways for machining metals. Lathe tools may benefit from deliberately-induced vibrations to prevent "chatter" which compromises the surface finish of the finished component. Ultrasonic drills, used on very hard ceramics, work by grinding or eroding material away - a liquid slurry around the drill bit contains loose hard particles which are smashed into the surface by the vibrations, eroding material away and creating more loose hard particles METAL FORMING CarnaudMetalbox R&D (now a part of Crown Cork and Seal - the biggest packaging company in the world) and Loughborough University developed a new aerosol can using a number of novel metal-forming processes, starting with ultrasonic necking (i.e. reducing the diameter of the can at one end). The advantage of using ultrasonics in this case was to minimise friction between the can and the die, thus reducing the forming force. Without ultrasonics the force was so high that the can body would buckle and collapse during the necking process. With ultrasonics a 30% reduction in can diameter could be achieved in a single operation (in conventional necking processes the maximum is typically about 5%). The ultrasonic forming process went into production making small-diameter aerosol cans in a UK factory. The production line still runs intermittently, making promotional packaging for several prominent customers. One of its products ("Fleurs de Paris" parfum deospray can) won a silver in the 1997 Metal Packaging Manufacturers Association awards. METAL WELDING Ultrasonics can be used to weld different metals together, without solder and flux or special preparation. The process is different to plastic welding in that the two components are vibrated parallel to the interface. This is a more intuitively logical method of generating friction between them, but frictional heating is not thought to be the prime mechanism of the process - the temperature needed to melt (or even soften) most metals would be very difficult to achieve. Instead the mechanism is thought to be diffusion-bonding: atoms of each part diffuse into the other when the two surfaces are brought together in close contact. The ultrasonics promotes this close contact by breaking down the surface oxide layers, allowing the "raw" metals to make contact. PLASTIC WELDING Plastic welding is used for a huge variety of products ranging from blister packs, cartons and small consumer goods up to car fuel tanks and dashboards. It works by generating heat exactly where it is needed - at the interface between the components to be joined. The components are clamped between a vibrating sonotrode and a fixed mounting. Strangely, the vibrations are usually applied perpendicular to the contact surface, although much of this vibration may be converted to in-plane movement. This also has the advantage that the clamping pressure will keep the sonotrode in contact with the component - serrated surfaces are generally not required. Best results are achieved when the components are clamped close to the interface ("near-field" welding) but if this is not possible then the process can still work at a distance ("far-field"). Staking, or insertion, is a variation of this process in which a metal part (generally a threaded bush) is driven into a hole in a plastic component, which then solidifies around it to form a permanent join. This is a convenient method of producing strong tapped holes in a plastic part. SIEVING Industrial sieves are normally agitated at low frequency to help the product to distribute itself evenly over the surface and to help the small particles go through. Vibrating the mesh at ultrasonic frequencies (in addition to this low-frequency oscillation) can improve the rate of flow dramatically, preventing the product from blocking the holes in the mesh and helping to separate the small particles from the large. SINTERING The powder-metallurgy process is used to manufacture top-quality steels and other metals. The powder must be packed as closely as possible before the sintering process begins to prevent the formation of voids or other weaknesses in the finished product. Published research papers indicate that a significant increase in the packing density can be achieved using ultrasonics. Can anyone confirm that this process is in production? NON-DESTRUCTIVE TESTING Ultrasonic waves are projected through a medium (water) and a object (carbon fiber) and the internal structure can be analized for foriegn objects because the sound waves are bounced at different rates through the foriegn material than expected.

### What is controlled by the amplitude of a sound wave?

The amplitude of a sound wave is the pressure of the medium at a given point.

### What must occur for a sound wave to be produced?

Sound needs a media to propagate. Sound can not propagate in a vacuum. Sound waves, unlike light, are essentially compression waves and the sound in order to move from one place to other needs molecules to compress and decompress against, hence the wave is transmitted. In a vacuum, there are no molecules. Hence no sound.