Max headgear: Eliminating noise from wireless headsets
Bluetooth speakerphones and headsets have become a ubiquitous standard for drivers around the world. Yet, the wireless devices were prone to problems with road noise, wind and other distracting sounds while driving.
“It’s true,” said Jim Conti, vice president of business development at BlueAnt Wireless. “Noise in the car could drown out your conversation on the first generation of Bluetooth headset devices. “
What’s the answer?
Using a wired headset attached to your cell phone is impractical, Conti said. Wires can get in the way of driving or hung up on clothes, seat belts and levers.
Enter “noise reduction technology,” the ability to filter out conversation from other sounds. It also is known as “voice isolation technology.”
According to Conti, the problem wasn’t with Bluetooth technology. It had to do with the way wireless devices translate sound.
“Your mind can hear everything even when you are in a noisy setting,” Conti said. “People learn to tune out one background noise while focusing on a specific sound. Voice isolation technology filters out extraneous sounds electronically.”
For example, suppose you are traveling on the freeway with your family. In the front seat your spouse is listening to music. In the backseat your children are playing DVDs. Road noise adds a third dimension to the crowd of sounds.
A wireless device with noise reduction technology identifies the speaker’s voice. It compares that to measurements of other sounds. Sounds that do not match the speaker’s voice are eliminated.
“Voices have a wide range of patterns,” Conti said. “That requires a combination of technologies to make sure you are filtering the right sounds.”
Some devices use a single microphone and rely on software to make distinctions, Conti said. These types of units cannot compare sound coming from different directions.
“Basic noise cancellation includes technology similar to squelch on the old CB radios,” Conti said. “It eliminates weak signals.”
More sophisticated headset units use dual microphones—one located near the speaker’s mouth and the other close the ear. Sound patterns from both microphones are compared, and items that do not match the speaker’s voice are removed.
Noise cancellation software cannot overcome a poorly-designed microphone, Conti said. A cheaply designed microphone may not provide enough signal differentiation to eliminate extraneous noises.
“The present threshold for eliminating wind noise is about 22 miles per hour,” Conti said. “Noise cancellation technology continues to improve, but it does not work if you driving a convertible at 55 miles per hour.”
What are the most important features when choosing a wireless headset with noise cancelation technology? Conti had the following recommendations:
- Noise cancellation technology may be found in headsets and stand-alone devices that attach to your vehicle’s visor. The difference depends on your driving environment. A headset can provide better privacy. A visor unit may provide better durability, simpler use and be less prone to getting lost.
- Decide how you will be using the wireless device. Are you driving in a convertible or closed vehicle? Do you drive mainly on the freeway with windows rolled up? In both instances noise cancellation technology can improve sound quality.
- Look for wind noise rating. Usually, this is estimated in vehicle speed (miles per hour).
- Use headsets that have dual microphones. The sound of the speaker’s voice entering one microphone is extracted from sound entering the second microphone.
- Compare device size and estimated battery life. Sometimes manufacturers use large components to overcome shortfalls in software processing. Or they trade off battery power, which reduces the talk time for the device.
“Price is less important than finding the right combination of technologies for your driving application,” Conti said. “Hardware and software work together to give you the best results.”