Titlebook: Electroacoustical Reference Data; John M. Eargle Book 2002 Springer Science+Business Media New York 2002 Damping.Modulation.Signal.Transdu

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Frequency and Wavelength in AirIn Figure 2, for frequencies from 10 Hz to 100 kHz, wavelength is plotted in meters (left ordinate) and in feet (right ordinate). Normal temperature is assumed. The relevant equations are: . and ..

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left-ventricle

Seizure

铁砧

Atmospheric Sound Absorption as a Function of Frequency and Relative Humidity, IIEssentially, the same data from section 5 are replotted in Figure 6, and extended to lower frequencies. The attenuation constant is given in dB per meter; in this form, it can be used to calculate the excess losses over distance due to atmospheric effects.

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Binge-Drinking

NC and PNC Noise Criteria CurvesNoise criteria curves, developed in 1957, are used to determine the so-called NC rating, quantifying as a single number the noise present in an architectural space. Most measurements are made in octave-wide bands from 63 Hz to 8 kHz.

IRS

Sound Transmission Class (STC) CurvesSound transmission class curves, shown in Figure 9, are used to determine, as a single number, the effectiveness of walls and other architectural barriers in isolating airborne noise between spaces.

defibrillator

Resonance Frequency for Pipes Open at Both EndsFigure 11 gives the nominal length of an open pipe that will resonate at a particular frequency. This occurs when the pipe is approximately equal in length to one-half the wavelength of the frequency. Pipes that are particularly large in diameter may need to be modified in length, in order to determine their actual “speaking length.”

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End Correction for PipesAssume that the open pipe in the previous example was specified as being of a particular diameter. We now want to determine what degree of end correction must be incorporated to attain the desired frequency. Figure 12 shows the relation between the increase in the speaking length of pipe and its length-to-radius ratio (L/R).