Sony MDR-NC300D Product Information page 7

[Merits of digitalization]
 In principle, computation is not affected by external electrical noise
Analog
NC
circuit
 High precision and no variation
Analog
 Complex shapes not possible with analog filters are possible with
digital filters
Analog
Frequency
Digital
NC
circuit
Digital
Digital
Frequency
S-Master
Digital Amplifier
Driver unit
DNC Software Engine
Digital Sound
Enhancer
CXD9952GR
Noise detection
microphone
A/D converter
DSP
AI Noise
Analyzer
A/D converter
Walkman and other AV devices