Noise Reduction Testing
Cycling Wind Noise Reduction Testing Procedures
Following are the results of a road test performed on May 10, 2015 in Portland, Oregon. Wind reducing devices tested include popular Wind-Blox and Cat-Ears products.
Testing was conducted by two of the founders of Wind-Blox to measure the effectiveness of the latest product, Wind-Blox Pro. The test objectives were two-fold:
- To quantify observations of improved air flow seen in the wind tunnel — in a real world audio test outside of the lab, and
- To compare the effectiveness of Wind-Blox and Cat-Ears products.
The results produced a 4.6 db improvement in wind noise reduction for the new Wind-Blox Pro over the current Wind-Blox Classic model. Wind-Blox welcomes any independent testing that might further establish measurement accuracy.
Equipment used in the test
- dB Meter
- Attachable microphones
- Attachment devices
Wind Noise Reduction Test Procedure
- The microphone was attached at the center of the rider’s outer ear in order to measure the wind at the focal point of sound reflection in the ear.
- The dB Meter was attached to monitor the sound from the microphones.
- The course was measured. The course of the measurement was a 1/4 mile lap in the parking lot with a slight hill which resulted in a speed profile between 11-14 miles per hour through each lap. This same speed range was used for each measurement made and all factors were kept identical between products measured.
- Baseline measurements. Five baseline measurements of the wind noise without wind blocking devices attached were made at different points in the experiment by riding the 1/4 mile loop three times each and recording an integrated average dB level as measured cumulatively throughout the duration of each loop. This was performed three times for every baseline and the average of the three 1/4 mile integrated measurements was set as the comparison baseline noise level to calculate improvement against.
- Testing. Each product was attached to the helmet strap in front of the ear with the microphone placement unchanged throughout the duration of all tests. The same three 1/4 mile laps were ridden at the same speed profile, and dB measurements were recorded and averaged.
|Product||Trial1||Trial 2||Trial 3||Average||Noise Reduced (Baseline less Average)|
|Baseline 1||72||73||72||72.3 dB||–|
|Wind-Blox Classic||53||52||50||51.6 dB||20.7dB (75.8%)|
|Wind-Blox Pro||48||46||47||47 dB||25.3dB (80.2%)|
|Cat-Ears Strap Wraps||59||60||61||60 dB||9.3dB (46.2%)|
|Cat-Ears Pro||56||54||52||54 dB||15.3dB (67.3%)|
|Baseline 2||67||74||67||69.3 dB||–|
|Cat-Ears Classics I||51||49||44||48 dB||17.3dB (71.1%)|
|Baseline 3||71||60||65||65.6 dB||–|
|Cat-Ears Classic II||44||42||43||43 dB||22.3dB (77.6%)|
|Baseline 4||67||67||67||67 dB||–|
|Cat-Ears Elite Tour||54||58||56||56 dB||13.3dB (62.4%)|
|Baseline 5||70||72||66||69.3 dB||–|
|Cat-Ears Elite Criterium||56||54||66||58.6 dB||10.7dB (53.3%)|
Percentage of noise reduction was calculated using the ratio for loudness formula (the most conservative of the three quantities), as cited by Sengpiel Audio Engineering:
x = 2(L2-L1)/10 where L2-L1 = decibel reduction measured.
Percentages are then calculated from the ratios (x) using [1 – (1/x)] x 100%.
Ambient Sound Testing
Following the wind noise road test, ambient sound level testing was performed to measure any impact of Wind-Blox devices on surrounding sound during a subsequent round of testing in June 2015.
Decibel measurements were made to determine any attenuation of ambient sounds (desirable sounds) due to these devices. Measurements were made using a steady fan noise. No measurable difference in ambient sound levels was detected with or without any of the wind noise suppression devices. Rather, a very slight (1-2dB) increase in ambient sound level was measured with the Wind-Blox devices on, perhaps due to sound reflections against the devices. No attenuation is to be expected due to the ‘open ear’ design, as there is no obstruction between the ear and the sound sources due to the location of helmet straps in front of the ear, but not covering the ear.
Wind Tunnel Lab Test Results
Following is the most recent lab test to compare Wind-Blox with Cat-Ears. Wind tunnel tests were conducted at George Fox University’s School of Mechanical Engineering Fluids Lab between September 2014 and March 2015 as part of an engineering project. The results of this test favor the Wind-Blox Pro model released in Spring 2016. Because the fan noise is significant, only the fluid flow imagery was observed in the wind tunnel (audio was measured during the road tests described above). The wind tunnel results demonstrated that the current models of wind blocking devices (covering only a portion of the cheek) allow air flow around the two ends of the wind blocking device with a vertical component of fluid convergence onto the ear. The Wind-Blox Pro rim-to-clip device blocks more air flow on the vertical plane of the ear with a longitudinal wave of fluid flow outside the ear without the vertical fluid flow component seen with partial-strap noise reduction devices such as the original Wind-Blox Classic and the Cat Ears products.
All data should be accurate and is based on publicly available information as of September 2015. One thing we discovered in our trials is that Cat Ears reduces most of the wind noise, much like Wind-Blox. We were very curious to see if the Cat Ears fur or faux fur design would make a significant difference. While it sounds good conceptually, our test could not register any difference with the fur or faux fur vs Wind-Blox. In contrast, Wind-Blox, especially the latest Pro version, produced better wind reduction without any noticeable loss of desired sound. Regardless, both products seem to do a good job reducing wind noise and contribute to the safety of the industry–even if they go about it using a different approach.
Wind-Blox products are patent-protected. US Patent Numbers D728,863 and D917,790.
All products are the property of their respective owners.