Plantronics Vista Plus DM15 digital adapter utilizes 2nd generation technology & DSP (Digital Signal Processing) to deliver unsurpassed levels of acoustic protection & exceptional sound quality. With Sound Guard DIGITAL, daily personal noise exposure is monitored & automatically controlled to aid compliance with new EU legislation. Constantly on guard, Sound Guard DIGITAL also identifies & eliminates sudden loud sounds, to avoid user discomfort. Plantronics Call Clarity DIGITAL combines a range of techniques to enhance sound quality. Its 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.