|
Home -> Research
& Demonstrations ->Flutter Echo in a Home Kitchen-Dining
Area
Flutter Echo in a Home Kitchen-Dining Area
In this home kitchen, the drywall ceiling and tile floor are parallel
to each other. Because of the "large" surface area, a handclap
reveals a very audible flutter ehco. Once the listener hears the flutter,
it's now also heard when people talk in the room. While the flutter
is fast and dies quickly, it's annoying to those who hear it.
 |
(left)
BEFORE
A photo showing the kitchen space and test microphone.
Listen to the sound of a handclap here.*
(278K)
Listen to a slowed down version (half speed) here.*
(419K)
* For best results, turn the volume on your playback system up
loud enough to hear the hiss on the recording. This will ensure
you're able to hear the tail-end of the impulse (clap) properly.
BE CAREFUL so you don't damage your speaker system! |
 |
(left)
AFTER
A photo showing the kitchen space and test microphone.
Listen to the sound of a handclap here.*
(273K)
Listen to a slowed down version (half speed) here.*
(461K)
* For best results, turn the volume on your playback system up
loud enough to hear the hiss on the recording. This will ensure
you're able to hear the tail-end of the impulse (clap) properly.
BE CAREFUL so you don't damage your speaker system! |
|
(above) Here's the ETC (energy time curve) before the tubes were
put in place. Notice the spikes in the first 25 milliseconds;
these are the first strong reflections. |
|
(above) Here's a colorful spectrogram of the space before any
tubes were added. Frequency is shown from bottom to top, and time
from left to right. Amplitude is shown using both color and physical
length of the horizontal line segments drawn. The longer the line,
the higher the amplitude. Red, orange, and yellow streaks indicate
strong reflections (room modes). |
|
(above) Here's the ETC (energy time curve) after the tubes were
put in place. Notice that the spikes in the first 25 milliseconds
are still present. With only four tubes placed on the floor and
the presence of other surfaces for reflection, these spikes will
still appear. However, if you study the before and after ETC screen
shot, you'll see that the overall level in the second (after)
shot is about 4dB lower. This is showing an increase in overall
signal-to-noise ratio; a good thing. |
| 
(above) Here's the spectrogram after the four tubes were placed
on the floor. Notice the change? Much less streaks of red and
orange, the overall decay is much quicker in the first 50 milliseconds. |
So what's the practical solution to this space? We can't leave the
cardboard tubes on the floor, that's for sure! What about treating the
ceiling? using a couple 2 foot wide and 4 foot long flourescent fixtures
with a rounded glass face would do the trick very nicely, not to mention
providing additional light to the area. Acoustical treatment doesn't
have to be obvious; it can be worked into other necessary elements if
you're creative enough.
Measurement Specifications:
- Toshiba Satellite 2535CDS (300MHz)
- Digigram VX Pocket V2 audio card
- SIA SMAART Intelligibility & Analysis 3.0 software
- Audio Control Industrial MP-400 Measurement Microphone Preamplifier
- Earthworks M30 microphone
- .WAV files recorded using W98 Sound Recorder; edited for length
using Macintosh Sound Sampler software
-
-
|
