Sound Level: an Enclosed Chamber with Sound Absorbing Walls Has

question 76

Multiple Choice

Sound level: 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, 78 m away and facing the window. The intensity level of the sound entering the window space from the loudspeaker is 79 dB. Assume the acoustic output of the loudspeaker is uniform in all directions and that the 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 entering through the window space is closest to

• A) 160 µW.
• B) 79 µW.
• C) 320 µW.
• D) 790 µW.
• E) 1600 µW.

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Definitions:

Promoter

A region of DNA that initiates transcription of a particular gene, controlling gene expression.

Gene

A unit of heredity made up of DNA, located on chromosomes, that encodes information necessary to build and maintain an organism's cells and pass traits to offspring.

DNA Nucleotide Sequence

The arrangement of nucleotides (adenine, thymine, cytosine, and guanine) in a strand of DNA, determining genetic information.

Posttranscriptional Processing

The series of modifications that RNA transcripts undergo after transcription, including splicing, editing, and polyadenylation.