An audio engineer takes decibel readings at distances of r1 = 11 m and r2 = 23 m from a concert stage speaker during a sound check. When he is r1 from the speaker, the engineer registers a decibel level of β1 = 119 dB on his loudness meter. (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?   (b)  How much power P, in watts, is coming from the speaker during the sound check 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?

12 gives the loudness of sound L (in dB) based on the intensity of sound I (in W/m²). The value I = 10 The formula L=10 log threshold for hearing for midfrequency sounds. Hearing impairment is often measured according to the minimal sound level (in dB) detected by an individual for sounds at various frequencies. For one frequency, the table depicts the level of hearing impairment. Category Mild Moderate Moderately severe Severe Profound Loudness (dB) 26≤L≤40 41≤L≤55 56≤L≤70 71 ≤L≤90 L>90 W/m is the minimal (a) If the minimum intensity heard by an individual is 9421.4 x 108 W/m², determine if the individual has a hearing impairment. Round to the nearest tenth. (b) If the minimum loudness of sound detected by an individual is 40 dB, determine the corresponding intensity of sound.

Problem #8: The noise from a grinder in a factory is 32000 times more powerful than the noise from a dishwasher. By how many decibels is the factory noise greater than the dishwasher noise? Problem #9: A loud sound is 90 dB. When the sound is reduced to 5% of its original intensity, what is the decibel level? Problem #10: At a rock concert, a dB meter registered 130 dB when placed 2.8m in front of a loudspeaker on the stage. What is the power output of the speaker, assuming uniform spherical spreading of the sound and neglecting absorption in air? Problem #11: By how many decibels do you reduce the sound intensity level due to a source of sound if you quadruple your distance from it? Assume that the waves expand spherically.

(a) The intensity of the sound from a certain MP3 player (without earbuds) is  4.1 × 10−5 W/m2.  Find the intensity level in decibels. (Round your answer to the nearest whole number.) dB(b) The intensity of the sound of the MP3 player in part (a) with earbuds is  5.0 × 10−3 W/m2.  Find the intensity level in decibels. (Round your answer to the nearest whole number.) dB