- #1
pasomatt
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I was conducting an experiment with a tone generator (330 Hz) in boxes of different sizes with a glass plate placed on top of the box. There is a receiver about .55 meters away. Without any interference, the receiver registered -41 db +/- 1 db. When the tone generator is placed in the box and left open, there is no discernible change in dbs. When the glass is placed on the box, the sound is increased by a range of 2 to 13 dbs.
Going into this, I expected the sound to be reduced, not amplified. Like rolling up a car window, or closing a window in your house to reduce the noise from outside. After realizing the sound was being amplified I was expecting this to be proportional to the amount off free space in the box. I.e. large box = more space = less of an increase in sound. This second part mostly held up.
In a space of .008 m^3 the sound amplification was 2.
In a space of .003 m^3 the sound amplification was 6.
In a space of .0005 m^3 the sound amplification was 8.
However, in a space of .0007 the sound amplification was 13.Does anyone know why the sound is not being dampened? Or can refer me to some sort of concepts/equations? I'm really struggling to model what is happening.
Let me know if you can help.
Here's an example of my setup:
Going into this, I expected the sound to be reduced, not amplified. Like rolling up a car window, or closing a window in your house to reduce the noise from outside. After realizing the sound was being amplified I was expecting this to be proportional to the amount off free space in the box. I.e. large box = more space = less of an increase in sound. This second part mostly held up.
In a space of .008 m^3 the sound amplification was 2.
In a space of .003 m^3 the sound amplification was 6.
In a space of .0005 m^3 the sound amplification was 8.
However, in a space of .0007 the sound amplification was 13.Does anyone know why the sound is not being dampened? Or can refer me to some sort of concepts/equations? I'm really struggling to model what is happening.
Let me know if you can help.
Here's an example of my setup: