An outside loudspeaker (considered a small source) emits soundwaves with a power

Question

An outside loudspeaker (considered a small source) emits soundwaves with a power output of 75 W. (a) Find the intensity 7.5 m from the source.
1 W/m2
(b) Find the intensity level in decibels at that distance.
2 dB
(c) At what distance would you experience the sound at thethreshold of pain, 120 dB?
3 m (a) Find the intensity 7.5 m from the source.
1 W/m2
(b) Find the intensity level in decibels at that distance.
2 dB
(c) At what distance would you experience the sound at thethreshold of pain, 120 dB?
3 m

Explanation / Answer

Given power of sound waves emitted by speakers   P = 75 W Intensity of sound at 7.5 m intensity of a point source           I = P / 4R2              = 75 / ( 4*3.14* 7.5 2 )             = 0.106 W / m2   Sound intensity level              = 10 log ( I / Io)                where Io    = 10 -12           = 10 log ( 0.106 / 10 -12 )               = 10 log 1*1013                = 10 * 13 log 1.06                 = 130 * 0.0253                 = 3.289 dB at = 120 dB           120 =10 log ( I / Io )             log ( I / Io ) = 12                       I / Io    = 10 12 Intensity of sound   I = 10-121012                                 = 1   W / m 2    intensity of sound is also equal to                     I = P /4R2                       1 = 75   / 4*3.14 * R2                    R = 2.44 m    at 2.44 m the sound intensity level is 120dB

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.