What are the steps for reducing sound intensity by 20 decibels?

Click For Summary

Homework Help Overview

The problem involves determining the distance a man must move from a siren to achieve a reduction in sound intensity level by 20 decibels. The context includes concepts from acoustics and the inverse square law.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the relationship between sound intensity and distance, referencing the equation for intensity level and the inverse square law. There are attempts to simplify the equation and clarify the steps involved in solving the problem.

Discussion Status

Some participants have offered hints and simplifications of the equation, while others express confusion about the application of the equations and the steps needed to arrive at a solution. There is an ongoing exploration of the mathematical reasoning behind the problem.

Contextual Notes

Participants are grappling with the application of logarithmic equations and the need for clarity on the initial intensity reference point. There is a mention of the original poster's understanding of the relationship between distance and intensity reduction.

ongobongo
Messages
3
Reaction score
0

Homework Statement


A man stands 3m from a siren. How far does he have to move to reduce the intensity level by 20 decibels?


Homework Equations


Intensity level = 10log(I/Io)
the inverse square law

The Attempt at a Solution


i know the answer is 30m because 10 times the distance drops the intensity by 20 dB although i don't understand how to use the equations to answer such a question, what are the steps involved
 
Physics news on Phys.org
welcome to pf!

hi ongobongo! welcome to pf! :smile:

start with 20 = 10 log(I/I0) :wink:
 
hi thanks for the hint but honestly i can't make heads or tails of the equation
 
simplify 20 = 10 log(I/I0)
 
I=10*10
√100 = 10
10*3 = 30m
 
ongobongo said:
I=10*10
√100 = 10
10*3 = 30m

yeees … i think you've got it, but i can't really tell :redface:

shouldn't your proof have an I0 in it somewhere? and some reference to logs?
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
Replies
2
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 4 ·
Replies
4
Views
7K
Replies
18
Views
3K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 4 ·
Replies
4
Views
7K
Replies
4
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K