Sound intensity at a microphone

In summary, the conversation discusses a problem involving a concert loudspeaker emitting 28.0W of sound power and a small microphone 51.0m away. Part A asks for the intensity at the microphone, which is found to be 8.57*10^-4 W/m^2. Part B asks for the sound energy impinging on the microphone, which is calculated to be 7.713*10^-6 J per second. However, the error is found to be in the conversion of the microphone's area, which is corrected to .00009m^2.
  • #1
vertabatt
30
0

Homework Statement


A concert loudspeaker suspended high off the ground emits 28.0W of sound power. A small microphone with a 0.900cm^2 area is 51.0m from the speaker.

A) What is I at the microphone?

B) How much sound energy impinges on the microphone in J?

Homework Equations


I = P/A
I = 4pir^2

The Attempt at a Solution


I have solved the answer to part A):

I = 28W/4pi(51)^2 = 8.57*10^-4 W/m^2The answer to part B is what's eluding me:

I know that at the microphone I = 8.57*10^-4 W/m^2

So:

8.57*10^-4 = P/.009m^2

P = 7.713*10^-6 W which is equal to J/s

Therefore my answer would be 7.713*10^-6 J of sound energy are impinged each second.

Mastering Physics is disagreeing with me. Any advice?
 
Last edited:
Physics news on Phys.org
  • #2
If I am doing something wrong or have not provided enough information, please let me know.

I must be missing something with this problem, because I can't seem to come up with a different answer than what I have shown.

Do I have the right approach? Am I making it too complicated by using the Intensity equation twice? Just a small nudge in the right direction would do wonders for me.
 
Last edited:
  • #3
Okay, took me long enough, but I found my error! As usual, it's a stupid one!

They reported the area of the mic as .9cm^2, originally I converted the dimension linearly saying that that was equal to .009m^2. In actuality the area is .00009m^2.

Duh.
 

What is sound intensity and how is it measured at a microphone?

Sound intensity is the amount of sound energy that passes through a unit area in a specific direction. It is typically measured in decibels (dB) using a microphone, which converts sound waves into electrical signals that can be measured. The intensity of sound at a microphone can vary depending on the distance between the sound source and the microphone, as well as the sensitivity and placement of the microphone.

What factors affect sound intensity at a microphone?

Several factors can affect the sound intensity at a microphone, including the distance between the sound source and the microphone, the sensitivity and placement of the microphone, and the characteristics of the sound itself (such as frequency and wavelength). Other external factors like background noise and reflections from surfaces can also impact the sound intensity at a microphone.

How is sound intensity at a microphone different from sound pressure?

Sound intensity and sound pressure are related but different measurements. Sound intensity is the amount of sound energy passing through a unit area in a specific direction, while sound pressure is the force per unit area exerted by sound waves. Sound intensity can be measured with a microphone, while sound pressure is typically measured with a pressure sensor.

What are some common methods for measuring sound intensity at a microphone?

There are several methods for measuring sound intensity at a microphone, including using a sound level meter, a microphone array, or a laser interferometer. Each method has its own advantages and limitations, and the choice of method depends on factors such as the accuracy and precision required, the type of sound being measured, and the environment in which the measurement is taking place.

How is sound intensity at a microphone used in practical applications?

Sound intensity measurements at a microphone are used in a variety of practical applications, such as noise control, environmental noise monitoring, and acoustic testing of products. It can also be used in fields like audio engineering and acoustic research to measure and analyze the characteristics of sound waves. By understanding the sound intensity at a microphone, we can better understand and control the impact of sound on our daily lives.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
2K
  • Introductory Physics Homework Help
Replies
7
Views
1K
  • Computing and Technology
Replies
3
Views
543
  • Introductory Physics Homework Help
Replies
5
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
3K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
1
Views
789
  • Introductory Physics Homework Help
Replies
8
Views
2K
Back
Top