Sound sources

In addition to the fundamental frequency, a periodic signal usually has energy at other fi e- 

Sounds such as [s], [f] and all vowels can be spoken as a continuous sound, and are therefore called continuants. By contrast stops are sounds which have a relatively short duration which can only be spoken as events and can not be spoke continuously. The [p] sound in pen or [t] sound in TIN are stops. Stops are produced by creating a closure somewhere in the vocal tract so that all air flow is blocked. This causes a build up of pressure, followed by a release where the air suddenly escapes. Because the sound is produced in this way, the sound must have a finite, relatively short duration and hence these sounds caimot be produced continuously. 

Sound can be created from sources other than the glottis. If the glottis is open, it will not generate any sound, but will allow the air stream to flow through. It is then possible to use combinations of the tongue, lips and teeth to form a constriction, and thereby 

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Echo directivity was experimentally studied for surface SH Wave probes and SH Wave angle probes. Frequencies used in the experiment were 5MHz and 2MHz, the angles of refraction 90°and 70°, the crystal size 10X 10mm and 5X5mm. The echo directivity was evaluated, using side drilled holes of various depths. The experimental results showed consistency with the calculation based on a point sound source assumption on the test surface in different phases. 

The sound pressure P was produced at the point D by the ultrasonic sound source which was generated at the point B in "n" order of the munite area AA by the incident beam. The sound pressure P is given by the equation(l)... 

The calculation based on a point sound source on the test surface in different phases showed consistency with the experiment. The assumption was proved to be reasonable and correct. 

I oise Transmission Reduction in HVACSystems. One common use of sound-absorbing treatment is to reduce noise transmission in heating, ventilating, and air-conditioning (HVAC) systems (6). The treatments ate used to reduce the transmission of fan noise and air turbulence noise through ducts into occupied spaces. Noise transmission reduction in duct systems is described in terms of insertion loss, the difference in sound power level or sound pressure level measured at a given location before and after installation of the treatment or sound attenuation, the reduction in sound power between two locations affected by a sound source. The units ate decibels. 

Noise Control Sound is a fluctuation of air pressure that can be detected by the human ear. Sound travels through any fluid (e.g., the air) as a compression/expansion wave. This wave travels radially outward in all directions from the sound source. The pressure wave induces an oscillating motion in the transmitting medium that is superimposed on any other net motion it may have. These waves are reflec ted, refracted, scattered, and absorbed as they encounter solid objects. Sound is transmitted through sohds in a complex array of types of elastic waves. Sound is charac terized by its amplitude, frequency, phase, and direction of propagation. 

In a fixed point in space, the magnitude of pressure will change according to the nature of the sound source,... 

The sound generation mechanism involves the transmission of acoustic energy in space. Therefore, the power of a sound source is the energy emitted in time units and is measured in W. 

When two sound sources are added, it must be remembered that the decibel is a logarithmic unit. Therefore, they cannot be added arithmetically but must be combined as follows ... 

CR Yellow Alert Gas leak in MSM Audible alarm, yellow flashing light on fire gas panel Uncertain could be real 1. Accept alarm 2. Cz area technician 3. Make PA announcement 4. Determine which gas detector is in alarm (its location) Suspend current operation. Scan panels for flashing yellow or red light. Turn around to MSM Fire Gas panel. Press "accept" button CCR Layout MSM Fire Gas panel Visual and audible Whatever op is doing when alarm occurs Initially disorientating because MSM does not have its own sound source. Alarm could be missed if second simultaneous alarm occurs on main bank of Fire Gas panels... 

The molecular sieve module fire and gas panel should be given its own alarm sound source and alarm accept control, since there is currently a risk of an alarm being missed. 

Toigerson T, Tnrekian KK, Turekian VC, Tanaka N, DeAngelo E, O Donnell J (1996) ""Ra distribution in surface and deep water of Long Island Sound Sources and horizontal transport rates. Cont Shelf Res 16 1545-1559... 

A practical consequence of architecture is to permit acoustical performances to large numbers of listeners by enclosing the sound source within walls. This dramatically increases the sound energy to listeners, particularly those far from the source, relative to free field conditions. A measure of the resulting frequency dependent gain of the room can be obtained from the EDR evaluated at time 0. This frequency response can be considered to be an equalization applied by the room, and is often easily perceived. 

Mcadams [McAdams, 1984] hypothesizes that die tracing of resonant amplitude by frequency modulation contributes to die distinctness of the sound in the presence of competing sound sources. 

In adding synthetic harmonic Mid aharmonic components, it is important that die two components fuse perceptually [Hermes, 1991] i.e., that the two components are perceived as emanating from the same sound source. Through informal listening, sine-wave phase randomization appears to yield a noise component that fuses with the harmonic component of the signal. 

The precedence effect describes the effect that sound sources are sometimes localized not according to the loudness of left versus right channel but on the origin of the first (not the loudest) wavefront. This time relationship between signals can be distorted by certain joint stereo coding techniques resulting in an altered stereo image. 

When a sound source is turned on in an enclosure, it excites one or more of the normal modes of the room. When the source is turned off, the modes continue to resonate their stored energy, each decaying at a separate rate determined by the mode s damping constant, which depends on the absorption of the room. This is entirely analogous to an electrical circuit containing many parallel resonances [Beranek, 1986], Each mode has a resonance curve associated with it, whose inxquality factor (Q) depends on the damping constant. 

Third, you have some voluntary control over the input to your exteroceptive sense organs, if you do not want to see something, you can look away or close your eyes if you do not want to hear something, you can move away from the sound source or put your fingers in your ears, in any state of consciousness, you have some voluntary control over exteroceptive functioning. But the control is limited if the sound is intense enough, it is difficult not to hear it at all, even with your hands over your ears. 

We believe his theory is most applicable to particular SRVs as he estimates the SPL at 30 m from the outlet resulting from an expanding jet at sonic velocity. This should be taken into consideration for incidentally occurring sound sources. 

In presentation and interpretation of results, NARL aims for objectivity, clear presentation, and statistical data treatment that is transparent to participants, internationally accepted and metrologically sound. Sources of chemical standards, statements concerning traceability and estimates of measurement uncertainty are included in the study report. 

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