Vertical Test Sketch
A sketch of testing a Ramp in the vertical position

Acoustic testing on a budget is a daunting task.  Many measurements need to be made, and sometimes several batteries of tests are required to get valid data. In the case of testing the Acoustic Ramp, I actually did an entire battery of tests that proved later to be invalid.  The good news, is that I learned from my mistakes and the second battery provided good repeatable and valid data.

My test process is essentially this: Shoot a swept sine wave from a high quality studio monitor at the diffuser and record what bounces back from the diffuser with a high-quality microphone placed on the circumference of a circle with the diffuser at its center. Then I move the microphone 5 degrees along the circumference and repeat the test.   Software assembles all of the data into impulse responses that when combined can create a sonogram which shows amplitude, frequency and the position of the microphone in relation to the diffuser.

Here are some photos showing the process of the testing:

Laying out the test locations
Laying out the test locations. Each piece of white tape is marked with the exact location of the microphone for each test position.

 

The test computer, audio interface and microphone preamplifier
The test computer, audio interface and microphone preamplifier. I am using a PC laptop with Windows XP, ARTA Acoustic Testing Software, a MOTU Traveler, and a Daking Mic Pre One microphone preamp for the testing.

 

The first test is with a flat panel
The first test is with a flat panel to be used as a control to compare between the effect of the diffuser and that of a flat reflective surface

 

Testing in the vertical position
Testing in the vertical position with a single acoustic ramp

 

A second view of the vertical position
A second view of the vertical position

 

Testing in the horizontal position
Testing in the horizontal position using a Mackine HR824 loudspeaker

 

Another view of testing in the horizontal position
Another view of testing in the horizontal position

 

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