### Image Credits:

1. Images #1, #2, #3, and #4: Argonne National Laboratory
2. Image #5: U.S. Air Force photo by Christopher Ball

1.
Aug 24, 2017 9:42 AM ET

Progress testing
by Sam Beall

I could see this technology being very helpful on large commercial projects. Typically we have a hard time doing blower door testing during construction because of trade sequencing. The first floor of a building might be fully clad while exterior foam is still being installed on an upper floor. By the time the building is fully air sealed, much of the air barrier is concealed. We do our best to test components and pieces of the assembly, but the acoustic approach could be a good supplemental approach.

2.
Aug 24, 2017 10:10 AM ET

Interesting. I wonder how it
by Jon R

Interesting. I wonder how it compares to some high flow source of fog directed against partitions (think smoking leaf blower).

3.
Aug 24, 2017 12:02 PM ET

Image 2 mix-up
by Antonio Oliver

Should the caption not indicate speaker on the left and microphone array on the right?

4.
Aug 24, 2017 12:34 PM ET

Response to Antonio Oliver

Antonio,
Thanks for catching the error. I have made the necessary correction.

5.
Aug 24, 2017 3:09 PM ET

Units problem
by Dana Dorsett

"Essentially, low-frequency sound (about 60 decibels or so, roughly the same as conversation in a restaurant or background music) is generated from the speaker and picked up by the microphone array."

Frequency is measured in hertz, intensity is measured in decibels. It's possible to have very high or very low frequency at very high or very low intensity. So what is that statement supposed to mean?

Since the units used were decibels I'll assume intensity, but I'm also curious about the frequency used, since the degree of acoustic attenuation of building materials varies with frequency, and a room's dimensions also have characteristic resonance frequencies that can affect the measurement.

6.
Aug 24, 2017 4:24 PM ET

Units Problem
by Peter Yost

Good catch Dana.

Here is SonicLQ inventor Ralph M's response:

"The statement I gave is indeed confusing. The 60 dB is, as you surmised, the sound pressure level (i.e. related to intensity or volume) but the sound is also a low frequency tone in the 50 to 200 Hz range. The frequency chosen will depend upon the background noise (we try to choose one without interference) and one that isn’t at a room resonance frequency (of which there are many in the 50 to 200 Hz range for most rooms)."

7.
Aug 24, 2017 4:44 PM ET

Makes sense. @ Peter Yost
by Dana Dorsett

Thanks for satisfying my curiosity!

It makes sense that they would need to vary the frequency to be able to tune out resonance & interference issues. A quarter wave of 100 Hz is about a yard and any unit-multiple of a quarter wave can "ring" creating a higher intensity and possible mis-calibration of the hole size, etc. In a given room there are many frequencies between 50-200 Hz that will have the issue, but in most rooms you'd also be able to find many frequencies that don't (much).

8.
Aug 24, 2017 5:26 PM ET

Even better is a standalone
by Jon R

Even better is a standalone square wave or filtered square wave pulse pulse - no resonance. Repeated to improve signal to noise.

9.
Aug 24, 2017 5:29 PM ET

Edited Aug 24, 2017 5:30 PM ET.

Square waves are a combination of the odd harmonics
by Dana Dorsett

It'll definitely resonate!

The fidelity of the squareness of the wave that gets out will also be distorted by the path's length and shape.

10.
Aug 24, 2017 9:23 PM ET

Edited Aug 25, 2017 5:26 AM ET.

Reflected sound is ignored in
by Jon R

Reflected sound is ignored with a time window - so no room resonance effect in the result. The single "impulse" pulses are far enough apart that they don't interfere with each other.

With cheap FFT, a continuous sine wave (which may or not be the case here) is one of the worst ways to measure sound attenuation along a path.

MLS stimulus may be better than impulse, but I haven't used it.

11.
Aug 25, 2017 11:15 AM ET

Room Resonances and Use of Non Pure Tones
by Ralph Muehleisen

Room resonances are only a problem if the interior microphone is at a room node. The person working inside could sense that and move the microphone. The ideas to use non-pure-tones (various types of pulses or MLS) iare good ones and the research team is working on that right now.

But, the field demos will concentrate on using tones because it's much easier to do the nearfield holography processing and the conversion of acoustic to infiltration data on pure tones. The method is not just trying to find the sound transmission loss across the enclosure so the team would need to make some serious changes to the NAH and other algorithms.

(Note: I am one of the technology inventors)