Plantronics VistaPlus DM15 digital adapter utilizes 2nd generation technology and DSP (digital signal processing) to deliver unsurpassed levels of acoustic protection and exceptional sound quality. With SoundGuard DIGITAL, daily personal noise exposure is monitored and automatically controlled to aid compliance with new EU legislation. Constantly on guard, SoundGuard DIGITAL also identifies and eliminates sudden loud sounds, to avoid user discomfort. Plantronics Call Clarity DIGITAL combines a range of techniques to enhances sound quality. It's automatic volume leveler maintains a constant listening volume, regardless of incoming call loudness. Selective frequency-response shaping maximizes speech intelligibility, whilst phone-line noise is also reduced.