Of course, the most important element of a Bluetooth headset these days – especially when it has to justify a premium price tag – is its audio quality, and the Discovery 975 happily fails to disappoint. Like the Voyager PRO it couples Plantronics' AudioIQ2 noise-cancelling technology and their WindSmart systems for avoiding wind noise, with the two adding up to incredibly natural sound. This is actually the first outing for dual microphones on a Plantronics headset, which the company tells us is tailored for everyday use rather than the more industrially inclined microphone setup of the PRO. We're seriously impressed with the amount of DSP (digital signal processing), echo-cancellation, equalization (Plantronics say 20-bands) and filtering packed into this 8g headset; having tested it first in noisy rooms and cars, then escalating through even louder situations, those on the other end of the line failed to hear any background noise whatsoever.