How Loud Is a Whisper at 3.5 Meters?

AI Thread Summary
The sound intensity of a whisper at a distance of 3.5 meters is calculated to be 6.50 x 10^-13 W/m². This intensity corresponds to a sound level of approximately -1.87 dB when using a reference intensity of 10^-12 W/m². The discussion highlights that the dB level of a whisper varies with distance, emphasizing the importance of knowing the reference distance for the original 20 dB measurement. The calculations rely on the formulas for sound intensity and decibel level. Understanding these principles is crucial for accurately assessing sound levels at varying distances.
kristibella
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Homework Statement


A. What is the sound intensity of a whisper at a distance of 3.5 m, in W/m2?
I know that a whisper is approximately 20 dB and P = 10-10 W/m2.

B. What is the corresponding sound intensity level in dB?

Homework Equations


I = Power/[(4pi)(3.5m)2)
dB = 10 log (I/Io).

The Attempt at a Solution


I = 6.50*10-13

dB = -1.87 (I used 10-12 W/m2 for Io)
 
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kristibella said:
I know that a whisper is approximately 20 dB and P = 10-10 W/m2.

dB level would depend on how far away you are. You know it's 20 dB at what distance from the whisperer?
 

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