| Which panel has the
strongest contribution regarding the disturbing noise? |
| Floor, cockpit, roof front,
roof rear, left side, right side, rear seat? |
| Which partial surfaces
are most productive for applying acoustic countermeasures? |
| Detailed Analysis: Distribution of sound contributions within each individual
panel! |
|
|
 |
 |
|
Panel Contribution Analysis (BPCA) |
|
|
|
Verification of Total Simulated Noise |
 read
more |
|
|
Comparison of BPCA with the
Conventional "Window Method" |
| read
more |
|
| Vehicle interior noise can be
regarded as the sum of all panel contributions which enclose
the compartment. In order to experimentally investigate the
sound contributions of individual panels, the so-called "window
method" is often used. However, the traditional window method
has a lot of disadvantages. Due to some fundamental drawbacks,
a new method has been invented by HEAD acoustics which is considered
a useful alternative. |
| The procedure has been tested
successfully on several vehicles. In this example, the
vehicle interior was subdivided into seven panels. In
detail, these were the floor, cockpit, roof front, roof
rear, left side, right side, and rear seat. |
| Each array comprised 20
sensors, resulting in a total of 140 investigated subpanels. |
 |
|
Example: subdivision into seven panels
Click here for a detailed view |
|
|
|
| Each individual panel can be investigated
in detail. In this example, the right side of the vehicle compartment
was subdivided into twenty subpanels. It is possible to analyze
and auralize each subpanel. A Campell diagram of the subpanel
5 is shown in the Figure (above). BPCA enables one to find the
critical subpanels easily and rapidly. |
| In another example, it can
be seen that the floor has the strongest contribution
to the interior noise. |
|
|
|
| 20 subpanels of the floor were
further analyzed to localize the problem sections. The method
works in the time domain, therefore contributions of the each
panel can be auralized and analyzed with different analysis
e.g. FFT vs. Time, Order analysis at critical rpm, etc. |
| In the figure below, the spectrum
of the calculated sum of all surface contributions (green) compared
with the spectrum of a real measurement (red, the vehicle interior
noise is aurally adequate recorded via binaural head microphone). |
| The comparison of both curves
shows a very good agreement between simulation and measurement. |
|
| Insulation material |
|
necessary |
|
no |
|
| Time duration |
|
appr. 2 weeks (10 - 20 panels) |
|
appr. 4 days (140 panels) |
|
Gained information
density |
|
medium (appr. 10 - 20 surfaces) |
|
high (140 surfaces) |
|
Flexibility in choice
of running condition |
|
in general restricted to test stand measurements |
|
full flexibility (street, test stand, wind,
rain, gravel road) |
|
Impact on vehicle
acoustics |
|
change of absorption, structural change |
|
no impact |
|
Applicable
frequency range |
|
from approx. 80 Hz (limitation due to mass
law); above 400 Hz limitations due to altered vehicle acoustics |
|
80 Hz - 2 kHz
depending on exciltations |
|
| Accuracy of results |
|
qualitative |
|
quantitative |
|
Panel
Contributions
