Mild interesting: Gobi Rack on a 5th gen decibel tests @ 80 MPH

[rob_dixon]

My not exactly scientific tests, however mildly interesting.

I used the Sound meter android app. Used exact same conditions, position, speed @ 80 MPH. for ~1.5 minutes. road is a "new" highway (HWY 51 in Phoenix) so generally very consistent.

1) No Rack (stock)
Average dB: 75
Max 79

2) Rack installed with no wind faring:
Average db: 77
Max 80.

It produced a deep low frequency hum, even at lower speed, very annoying.

3) Rack installed wind faring installed
Average dB: 76
max 81

Deep hum absent, but indeed more wind noise right overhead as one would expect.
_____
Anyway, there you go folks. I have screenshots which I planned to post but images dont seem to post correctly.

 

[ysasi]

Out of curiosity (from the acoustic engineer in me) where and how was your phone being held?

 

[rob_dixon]

Out of curiosity (from the acoustic engineer in me) where and how was your phone being held?

In hand, elbow on center console holding in middle right at dashboard line level..basically in front of radio face about 6 inches back.

Phone was a pixel 2 for whats its worth - you might know the mic sensitivity and therefore accuracy of the readings more than i would. I just thought it would be fun to report.

 

[ysasi]

In hand, elbow on center console holding in middle right at dashboard line level..basically in front of radio face about 6 inches back.

Phone was a pixel 2 for whats its worth - you might know the mic sensitivity and therefore accuracy of the readings more than i would. I just thought it would be fun to report.

Nicely done.

If you're wondering about that low frequency hum without the wind fairing, it's due to vortex shedding:

Vortex Shedding

Probably some difference between the lightbar/multi-light and rise/no-rise options. Might need to test out my Gobi when it (hopefully) shows up next month.