*72. Go Review Conceptual Example 8 as background for this problem. A loudspeaker is generating sound in a room. At a certain point, the sound waves coming directly from the speaker (without reflecting from the walls) create an intensity level of 75.0 dB. The waves reflected from the walls create, by themselves, an intensity level of 72.0 dB at the same point. What is the total intensity level? (Hint: The answer is not 147.0 dB.)

Problem #4: What sound intensity level in dB is produced by earphones that create an intensity of 4.00 x 10-2 W/m2? Problem #5: What is the intensity of a sound that has a level 7.00 dB lower than a 4.00 × 10–9 W/m2 sound? Problem #6: What is the intensity of a sound that is 3.00 dB higher than a 4.00 × 10–9 W/m2 sound? Problem #7: If a large housefly 3.0 m away from you makes a noise of 40.0 dB, what is the noise level of 1000 flies at that distance, assuming interference has a negligible effect?

A sound wave travels from air (Z 413 kg m2 s1) to a liquid with a density of (950 kg m3) and a speed of sound in it (1-cm s 75000). 1) What percentage of the wave is reflected at the boundary? 2) What percentage of the wave travels across the boundary?

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What is the wavelength of a 256-hertz sound wave in air at 31 degrees Celsius? a b с Od 0.773 m 8.53 * 10^-7 m 1.17*10^6 m 1.37 m

Dolphins of the open ocean are classified as Type II Odontocetes (toothed whales). These animals use ultrasonic "clicks" with a frequency of about 55 kHz to navigate and find prey.  Suppose a dolphin sends out a series of clicks that are reflected back from the bottom of the ocean 90 m below. How much time elapses before the dolphin hears the echoes of the clicks? (The speed of sound in seawater is approximately 1530 m/s.) What is the wavelength of 55 kHz sound in the ocean?

While taking off, a jet engine emits 132.0 W of sound power as it reaches a height of 97 m. A small microphone with a 1.00 cm^2 area is on the ground directly below the jet. a) What is the sound intensity at the position of the microphone? b) What is the sound intensity level at the position of the microphone? c) How much sound energy impinges on the microphone in 4.0 s?

6. You measure the intensity level of a sound wave 6 cm from its source (treat as a point source), and the result is 84 dB. What is the intensity of this sound wave? Answer:

You hear a song from your playlist you haven't heard in a while and it warrants you to commence singing.  As you are sing, the power of the compression wave you create is approximately 579.05 nW (note, nW is nano-Watts).  What is the intensity of this sound as measured by your roommate who is standing 9.89m from you?  Please give your answer in units of nW/m2.  This unit is not a common one.  Usually, the unit would simply be Watts per square-meter (which would be your answer divided by a million!).  This goes to show you that are ears are amazingly sensitive to very tiny sound intensities.  Note: Intensity was a topic covered in section 11.1, and I will provide the formula: ?=?/?I=P/A where ?P is the power in units of Watts, and ?A is the surface area of a sphere of radius "L" (in this problem).