Sound Produced By Humans
Music or sound is an essential ingredient of life. Without it life becomes sad and miserable. In general, sound is a form of energy which gives us hearing experience. Ever thought how it is produced by various instruments and by living organisms. It is produced because of vibrations. Whenever we speak loudly and touch our throat, we feel vibrations.
Frequency Response And Acoustic Impedance Of The Saxophone
The way in which the reed opens and closes to control the air flow into the instrument depends upon the acoustic impedance at the position of the reed, which is why we measure this quantity. The acoustic impedance is simply the ratio of the sound pressure at the measurement point divided by the acoustic volume flow . If the impedance is high, the pressure variation is large and so it can control the reed and the flow of air past it. In fact, the resonances, which are the frequencies for which the acoustic impedance is high, are so important that they ‘control’ the vibration of the reed, and the instrument will play only at a frequency close to a resonance. . The section below shows how the major features of the saxophone’s shape give rise to its acoustic impedance spectrum, and thus to how it operates.
We repeat the graph of the impedance spectra of the lowest notes of soprano and tenor. We also have a data base of saxophone acoustics that shows saxophone impedances and sound files for many notes and some multiphonics.
For frequencies above about several hundred hertz, the resonances become weaker with increasing frequency. This is due to the ‘friction’ of the moving air against the inside of the instrument . This affects higher frequencies more than low.
Human Hearing And Speech
Humans are generally capable of hearing sounds between 20;Hz and 20;kHz . Sounds with frequencies above the range of human hearing are called ultrasound. Sounds with frequencies below the range of human hearing are called infrasound.
- Typical sounds produced by human speech have frequencies on the order of 100 to 1,000;Hz.
- The peak sensitivity of human hearing is around 4000;Hz.
- locating the source of sound
- Interaural Time Difference
- Interaural Phase Difference Phase differences are one way we localize sounds. Only effective for wavelengths greater than 2 head diameters .
- Interaural Level Difference Sound waves diffract easily at wavelengths larger than the diameter of the human head . At higher frequencies the head casts a “shadow”. Sounds in one ear will be louder than the other.
Closing Our Ears When We Hear Loud Noise
If you hear a very loud sound, what do you do? You cover your ears. How do you think that helps? When you cover your ears, you shut off the air inside your ears from the rest of the atmosphere. The sound waves travelling around you are now unable to get through to your ear or the intensity of the sound you hear is greatly reduced. Blocking your ears creates a discontinuity in the medium due to which the flow of sound energy is disturbed. Through this, we can make a very important observation; Sound waves rely on the medium for propagation. The propagation of the sound wave is not possible through the vacuum. The medium here can be gas, liquid or solid. The speed of sound when it is travelling through a medium depends on the type of medium. The speed of sound when travelling through air is 343 m/s or 1,235 km/h.
Sound Propagation In Water And Solids
Because it results from their compressibility, sound spreads in all media, especially in liquids such as water. In the seas, this phenomenon is of considerable interest because, since light does not penetrate to great depths, it provides one of the preferred means of diagnosis. Fishermen use sound or ultrasound to detect schools of fish, geographers survey underwater landforms and national navies around the world identify ships and submersible friends or enemies in their vicinity. It is also with ultrasound that marine mammals communicate. The range of frequencies that can be used in seawater ranges from 30 Hz to 1.5 MHz, a value 100 times higher than the human audible limit of about 15,000 Hz. The speed of sound in the water is about 1450 to 1550 m s-1. As shown in Figure 8, it varies mainly with temperature and depth, i.e. with pressure, but is not very sensitive to changes in salinity .
References and notes
Cover image. The acoustic waves emitted by a radially vibrating sphere propagate in all directions in the form of alternating compression and relaxation of the gas layers adjacent to each other. Source: By Thierry Dugnolle , via Wikimedia Commons]
The compressibility of air is both large enough for this fluid medium to carry sound and small enough to justify the use of incompressible approximations to describe aerodynamics at speeds well below the velocity of sound.
The Head Joint Is Not Perfectly Cylindrical In Shape
The head joint tube narrows toward its left end. This is described as a tapered tube. In musical instrument terminology, “tapering” refers to the manner in which a tube opens out. Yamaha manufactures three different types of tapered tube.
Internal shape of the head joint. Yamaha’s three types of tapering.
A G-tapered tube essentially expands evenly in diameter from the thin end to the thick end. It offers a strong resistance when blown and produces a deep sound. A C-tapered tube has a streamlined shape like a liquor bottle. It is easy to blow into and produces a light timbre. The shape of a Y-tapered tube is a combination of the G- and C-tapered tube shapes, offering moderate resistance when blown and producing a delicate sound.
Different Sounds Through Tuning
Equal tension on the top and bottom headGreater tension on the bottom head
It is also important to tune the drums to one another. For example, if the tom-toms are close in tone, the sound will be unclear, and so these drums are generally tuned to different tones. Percussion instruments do not have the clarity of pitch found in the wind and stringed instruments, but the more drums there are, the more important tuning is to creating a smooth, pleasing sound. Several tom-toms are sometimes tuned to a musical scale and used to play a melody.
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Tuning Changes The Sound
“Drum tuning” does not mean tuning the drum to a pitch like “C” or “D” but rather to the drum’s resonant frequency or a certain tone preferred by the drummer. If the tightness of the head is not uniform, the tone of the drum will change depending on where the drum is struck, and it will be a muddy tone at that. Thus, the drum head must be tightened so as to produce the same tone when struck in different places.The top head and bottom heads are also tuned to different tensions. If both the top and bottom heads are given the same tension, the sustain of the tone is long, but the volume is low. If this condition is changed, however, the drum becomes louder. In addition, if the bottom head is tighter than the top head, it becomes louder, and the tone rings longer. However, if the bottom head is looser, the tone does not ring so long, and the tone is flatter. The greater the difference in tension between the two heads, the greater the change in tone.
What Happens Inside The Head Joint
A reflective plate and natural cork are situated to the left of the embouchure hole. We will show this on an acrylic flute built for research purposes.The reflective plate is fixed in a position 17 mm from the center of the embouchure hole. Under normal circumstances, do not turn the crown , as this will cause the reflective plate to slip out of place. Breath injected into the flute strikes the reflective plate and is directed to the right. The quality of the cork influences the quality of the sound.
Interior of head joint
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Characteristics Of Sound Waves
There are five main characteristics of sound waves: wavelength, amplitude, frequency, time period, and velocity. The wavelength of a sound wave indicates the distance that wave travels before it repeats itself. The wavelength itself is a longitudinal wave that shows the compressions and rarefactions of the sound wave. The amplitude of a wave defines the maximum displacement of the particles disturbed by the sound wave as it passes through a medium. A large amplitude indicates a large sound wave. The frequency of a sound wave indicates the number of sound waves produced each second. Low-frequency sounds produce sound waves less often than high-frequency sounds. The time period of a sound wave is the amount of time required to create a complete wave cycle. Each vibration from the sound source produces a waves worth of sound. Each complete wave cycle begins with a trough and ends at the start of the next trough. Lastly, the velocity of a sound wave tells us how fast the wave is moving and is expressed as meters per second.
Sound wave diagram. A wave cycle occurs between two troughs.
The Relationship Between The Speed Of Sound And The Frequency And Wavelength Of A Sound Wave
Sound, like all waves, travels at certain speeds through different media and has the properties of frequency and wavelength. Sound travels much slower than lightâyou can observe this while watching a fireworks display , since the flash of an explosion is seen before its sound is heard.
The relationship between the speed of sound, its frequency, and wavelength is the same as for all waves:
where v is the speed of sound , f is its frequency , and Î» Î» is its wavelength . Recall that wavelength is defined as the distance between adjacent identical parts of a wave. The wavelength of a sound, therefore, is the distance between adjacent identical parts of a sound wave. Just as the distance between adjacent crests in a transverse wave is one wavelength, the distance between adjacent compressions in a sound wave is also one wavelength, as shown in Figure 14.7. The frequency of a sound wave is the same as that of the source. For example, a tuning fork vibrating at a given frequency would produce sound waves that oscillate at that same frequency. The frequency of a sound is the number of waves that pass a point per unit time.
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The Vibration Of The Head Shakes The Entire Drum
Striking the head of the drum changes its shape and compresses the air inside the shell. The compressed air presses on the bottom head and changes its shape. Then, these changes are transmitted to the drum shell and reflected back, and this action is repeated, creating a vibration. These vibrations of the top and bottom heads create vibrations in the air, which become sound, and eventually, as the head vibrations are dampened, the sound diminishes.
Amplitude Intensity Loudness Volume
Amplitude goes with intensity, loudness, or volume. That’s the basic idea. The details go in a .
- Unlike our ears and hydrophones, fish ears don’t detect sound pressure, which is the compression of molecules. Instead, they perceive something called particle motion, the tiny back-and-forth movements of particles in response to sound waves.
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Speed Frequency And Wavelength
In a gas like air, sound propagation results from an essential property: the mobility of molecules, with an average speed of about 480 m/s under normal conditions . But this agitation does not have a privileged orientation: it diffuses the energy of the tremor in all directions. However, the speed of sound propagation in the air, called celerity, implies that all molecules located in a very small volume undergo the same ordered and collective displacement. This explains why the speed of sound, although linked to the average speed of molecules, is only a fraction of this average speed, around 340 m/s.
This sound velocity is very low compared to the speed of light . This explains why the spectator of a football match, sitting in the stands at a distance of about 170 m from the centre circle, only hears the players shot half a second after seeing his foot hit the ball. On the other hand, over relatively short distances such as the dimensions of a concert hall, sound waves are able to accurately convey very subtle information that music lovers appreciate. A well-known exercise: in stormy weather, knowing that the perception of lightning is almost instantaneous, how can we assess how far away the storm has just broken?
periodTTthe frequencyf = 1/TcT fwavelength of the sound vibration = cT = c/f
Why Is Sound Produced
.Why does our ears interpret that as a sound ?
VASUbhagwat said:yes, but what happens in a vibration, that makes it produce a sound.Why does our ears interpret that as a sound ?
VASUbhagwat said:we generally say that the vibrations of the ear drum produces the sound,
VASUbhagwat said:Why does our ears interpret that as a sound
VASUbhagwat said:yes, but what happens in a vibration, that makes it produce a sound.Why does our ears interpret that as a sound ?
Kori Smith said:Your ears don’t ACTUALLY perform transformations on the signals you hear,
VASUbhagwat said:So, is it that, that whatever sound we hear is heard by every human, animals etc? So how is it possible that every brain of every organism produces the same sound?
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Properties Of Sound Waves
Sound is a wave. More specifically, sound is defined to be a disturbance of matter that is transmitted from its source outward. A disturbance is anything that is moved from its state of equilibrium. Some sound waves can be characterized as periodic waves, which means that the atoms that make up the matter experience simple harmonic motion.
A vibrating string produces a sound wave as illustrated in Figure 14.2, Figure 14.3, and Figure 14.4. As the string oscillates back and forth, part of the stringâs energy goes into compressing and expanding the surrounding air. This creates slightly higher and lower pressures. The higher pressure… regions are compressions, and the low pressure regions are rarefactions. The pressure disturbance moves through the air as longitudinal waves with the same frequency as the string. Some of the energy is lost in the form of thermal energy transferred to the air. You may recall from the chapter on waves that areas of compression and rarefaction in longitudinal waves are analogous to crests and troughs in transverse waves.
The Relationship Between The Diameter Depth And Tone
The tone, sustain, and projection of a drum is affected by the shape of the shell.The primary role of the drum is to resonate with the vibration of the head. The larger the volume of the resonating body, the lower the characteristic frequency, and the easier it is to resonate in the lower frequency band, while the smaller the volume, the easier it is to resonate in the higher frequency band. In other words, the larger the diameter, or the deeper the shell, the thicker and heavier the tone, and the smaller or shallower the shell, the brighter and lighter the tone.Drummers select drums with certain diameters or depths to match the style of music they perform, and they tune the drum heads to their liking to express a rainbow of tonal qualities in their music.
Examples Of Sound Produced By Vibrations
Let us consider an example that gives a clear idea about how sound is produced by vibrations in physics.
One of the simple and best examples of sound produced with vibrating objects is the guitar.; If we observe the guitar, some parallel strings will be there. Here the air is the medium. It helps to produce sound when we create vibration among the strings.;
Another well-known example is the tuning fork. It also explains how sound is produced with vibrating objects. The tuning fork is like the handle with the two tunes. Suppose we hit the tuning fork with the rubber hammer. In that case, it creates vibration among the two tines as the air molecules surrounded by the tuning fork get disturbed and undergo compression or expansion according to the tines’ reaction. If we hit Victor the rubber hammer multiple times, they keep on undergoing either compression or expansion, which results in the formation of multiple waves. These waves lead to the propagation of sound. The append soundwaves can be transmitted with the help of pressure waves available in the object itself. In this way, the sound can be produced by the vibrating objects as far as we can apply some force on the medium or object.
Characteristics Of A Sound Wave
We can describe a sound wave by its
- amplitude and
A sound wave in graphic form is shown in Fig. 5, which represents how density and pressure change when the sound wave moves in the medium. The density as well as the pressure of the medium at a given time varies with distance, above and below the average value of density and pressure. Fig. 5 and Fig. 5 represent the density and pressure variations, respectively, as a sound wave propagates in the medium.
Compressions are the regions where particles are crowded together and represented by the upper portion of the curve in Fig. 5. The peak represents the region of maximum compression. Thus, compressions are regions where density as well as pressure is high. Rarefactions are the regions of low pressure where particles are spread apart and are represented by the valley, that is, the lower portion of the curve in Fig. 5. A peak is called the crest and a valley is called the trough of a wave.
The distance between two consecutive compressions or two consecutive rarefactions is called the wavelength, as shown in Fig. 5, The wavelength is usually represented by . Its SI unit is metre .
How the brain interprets the frequency of an emitted sound is called its pitch. The faster the vibration of the source, the higher isthe frequency and the higher is the pitch, as shown in Fig. 6. Thus, a high pitch sound corresponds to more number of compressions and rarefactions passing a fixed point per unit time.
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