An enclosed chamber with sound absorbing walls has a 2.0 m × 1.0 m opening for a

Question

An enclosed chamber with sound absorbing walls has a 2.0 m × 1.0 m opening for an outside window. A loudspeaker is located outdoors, 10 m away and facing the window. The intensity level of the sound entering the window space from the loudspeaker is 55 dB. Assume the acoustic output of the loudspeaker is uniform in all directions and that acoustic energy incident upon the ground is completely absorbed and therefore is not reflected into the window. The threshold of hearing is 1.0 × 10-12 W/m2. The acoustic power output of the loudspeaker is closest to

Explanation / Answer

SOLUTION-The intensity level is given as

         = 10 dB log (I / Io )

     Given = 55 dB and Io = 1x10^-12 W/m^2 ( constant)

      on substiution

       55 dB = 10 dB log ( I / 1x10^-12)

        4.1 = log ( I / 1x10^-12 )

       I = (1x10^-12 ) antilog (4.1 )

         = 1.2589x10^-8 W/m^2

    The intensity output is

       P = IA

          = (1.2589x10^-8)(4 R^2 )

   here R = 10m , on substitution

       P = (1.2589x10^-8)( 4 )(78)^2

          = 0.0002

OPTION D. 2.0×103 W IS CORRECT

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

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