# Waves: Calculate the sound intensity from two speakers

• Karl Karlsson
In summary: Great job!In summary, two similar speakers emitting a signal of frequency đť‘“ are connected to a stereo system. Speaker B's signal is inverted, with positive voltage becoming negative and vice versa. A sound intensity meter shows 80.0 dB at 1.0 m in front of each speaker when only that speaker is turned on. When both speakers are turned on, the sound intensity level of the audience will be determined by the equation ##I_{audience} = 2I_{speaker}##, taking into account that intensity is proportional to the square of amplitude. The sound speed is 340 m/s.
Karl Karlsson
Homework Statement
Two similar speakers are connected to a stereo system that emits a signal of frequency đť‘“. However, the signal to speaker B is inverted so that positive voltage becomes negative (but with the same absolute value) and vice versa for negative voltages that become positive. A sound intensity meter shows 80.0 dB at a distance of 1.0 m in front of each of the speakers when only that speaker is turned on. How large will the sound intensity level of the audience be when both speakers are turned on? The sound speed is 340 m / s.
Relevant Equations
B=10lg(I/10^-12)
Two similar speakers are connected to a stereo system that emits a signal of frequency đť‘“. However, the signal to speaker B is inverted so that positive voltage becomes negative (but with the same absolute value) and vice versa for negative voltages that become positive. A sound intensity meter shows 80.0 dB at a distance of 1.0 m in front of each of the speakers when only that speaker is turned on. How large will the sound intensity level of the audience be when both speakers are turned on? The sound speed is 340 m / s.

The images below contains a picture of the problem, some values and my try of the problem. Is my solution correct? If not then why?

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Your work looks good to me overall except near the end. Did you take into account that ##I## is proportional to the square of ##A## when writing the equation at the bottom of the third image?

Last edited:
TSny said:
Your work looks good to me overall except near the end. Did you take into account that ##I## is proportional to the square of ##A## when writing the equation at the bottom of the third image?
Oh, wow. Silly me, I even wrote that the intensity was proportional to the square of the amplitude above on that same page. Thanks! I looked through it again now and I can't find anything else that is wrong either.

Everything else looks good to me.

## 1. What is sound intensity?

Sound intensity is the amount of energy that a sound wave carries per second per unit area. It is measured in watts per square meter (W/mÂ˛).

## 2. How is sound intensity calculated?

Sound intensity can be calculated by taking the square of the sound pressure and dividing it by the acoustic impedance of the medium. It can also be calculated by measuring the power of the sound wave and dividing it by the surface area it is passing through.

## 3. How do two speakers affect the sound intensity?

When two speakers are used, the sound intensity is affected by the constructive and destructive interference of the sound waves produced by each speaker. This can result in areas of high and low sound intensity, depending on the distance and alignment of the speakers.

## 4. What is the difference between sound intensity and loudness?

Sound intensity is a measure of the physical energy of a sound wave, while loudness is a subjective perception of how loud a sound is. Loudness is affected by factors such as the sensitivity of the human ear and the distance from the source of the sound.

## 5. How can sound intensity be measured?

Sound intensity can be measured using a sound level meter, which measures the sound pressure level in decibels (dB). It can also be calculated using specialized software or equipment that analyzes the frequency and amplitude of the sound wave.

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