An audio engineer takes decibel readings at distances of r1 = 11 m and r2 = 21 m from a concert stage speaker during a soundcheck. When he is r1 from the speaker, the engineer registers a decibel level of β1 = 114 dB on his loudness meter. Part A: What is the intensity of the sound, I1, in watts per square meter, that is measured by the loudness meter when the engineer is a distance of r1 from the speaker?  Part B: How much power P, in watts, is coming from the speaker during the soundcheck at distance r1?  Part C: Assuming that the speaker output does not change between the two measurements at r1 and r2, what sound intensity level β2, in decibels, will the loudness meter report when the engineer is at a distance r2 from the speaker?

A 38.0-Hz sound wave is barely audible at a sound intensity level of 60.0 dB. The density of air at 20.0°C is 1.20 kg/m3. Speed of sound in air at 20.0°C is 343 m/s. What is the displacement amplitude of a 38.0-Hz sound wave? What is the ratio of the displacement amplitude to the average distance between molecules in air at room temperature, about 3.00 nm?

Because the human ear is so sensitive to sounds, it can detect very small intensities.  The lower intensity that a human can hear (which is represented with the symbol I0 ) is about 1x10-12 W/m2. However, a loud music venue may have sounds that are near 1.0 W/m2 (though sound as this intensity would cause permanent damage to your ears).  Because the human ear can detect frequencies over such a large range of intensities, more often a sound intensity level is used.  This level is defined as: β=10⋅log10II0   and the unit is dB which stands for deci-bels (or just decibels).  If a person speaks with an intensity of 2.443 μ W/m2, what is the sound intensity level in decibels?  Note: In the space below, please enter you numerical answer.  Do not enter any units.  If you enter units, your answer will be marked as incorrect.

A loudspeaker on a tall pole broadcasts sound waves equally in all directions. What is the speaker’s power (in watts) output if the sound intensity level is 90 dB at a distance of 25 m? Hint: Assume the pole is tall enough that we don’t have to worry about the ground absorbing or reflecting sound. The intensity is  Intensity (I) = Power (P)/Area(A). At a far point (r) from the source A =4 pi r2