As a firefighter, you find yourself at the bottom of a burning high rise. A resident is trapped on a floor which is 105 m from you and the street. Your team has spread the Life Safety Net for the resident to jump onto safetly. The siren is shut off. The nosey spectators are quiet. However, it is a busy street. How loud, in decibels, should your bullhorn be in order for the resident to hear you? dB

You and your roommate decide to throw a party. You rig up three speakers with a combined decibel level of 83.5 db. You know that speaker one is 78.0 dB and speaker 2 is 76.0 dB. The sticker on the back of speaker 3 is missing, so you will have to calculate how many decibels it is. How many decibels is the third speaker?

A loudspeaker on a pole at the same height as your ears is radiating 100 W of sound energy in all directions. You are walking directly toward the speaker at 0.60 m/s. Assume your ears are 20 m away from the loudspeaker itself and, although it is not realistic, ignore all reflections of sound from nearby objects such as the ground. What is the sound intensity level at the location of your ears? Express your answer with dB units. ► View Available Hint(s) B Submit Part B dß dt = Submit μÀ || Value What is the rate (dB/s) at which the sound intensity level is increasing? Hint: Use the chain rule and the relationship log₁0 x = ln x/ ln 10. Express your answer in decibels per second. ► View Available Hint(s) Units VE ΑΣΦ www ? ? dB/s

The softest sound a human ear can hear is at 0 dB (Io = 10-12 W/m2). Sounds above 130 dB cause pain. A particular student's eardrum has an area of A = 51 mm^2. a. What is the most power, in watts, the ear can receive before the listener feels pain?  b. What is the smallest power, in watts, the ear can detect?

An intensity detector can be moved along a straight track. a source of spherical waves is placed at one end of the track. When the detector is 2 m away from the source, it measures an intensity of 80 W/m2. What distance do we need to move the detector from that position to get a measurement 13 dB lower? Answer: 6.95m

An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic waves that travel 1530 m/s in seawater. How deep is the water directly below the vessel if the time delay of the echo to the ocean floor and back is  8 s?

30. A man drops a rock into a well and he hears the splash 3.00 seconds later. If the air temperature is 27°C, how far below the top of the well is the surface of the water? Assume that the speed of sound is constant, and you may ignore the effects of air resistance.