Sony MDR-NC500D - Manual (Page 7)

7 GB
GB
Comparison between Feedback Type and Feedforward Type
Noise canceling effect
Anti dependency of noise
canceling effect against
individual difference / fitting
difference
Miniaturization
2.2. System configuration of MDR-NC500D
The Internal Block Diagram of MDR-NC500D is shown below:
The noise detection microphone of MDR-NC500D collects noise
around the ear.
The noise signal is digitized through the microphone amplifier and
high-speed A/D converter and is inputted in Digital Signal Processor
(DSP). Then the DNC software engine inside DSP generates the canceling
signal, which is inverted to the original noise.
Meanwhile, the regenerative signal of a music source supplied from
the audio input terminal is digitized by the high-speed A/D converter and is
inputted in DSP. Then, its frequency characteristic is adjusted by the digital
equalizer inside DSP. After the canceling signal is added, the regenerative
signal is reproduced as a sound by way of the high-speed D/A converter,
the headphone amplifier and the driver unit.
Mixing of the reproduced sound and the outside noise at the ear
negates only environmental noise, making it possible to enjoy music etc.
calmly.
Feedback type
Excellent
Better
Less suitable
Feedforward type
Good
Average
More suitable
Continued
Internal Block Diagram of Noise Canceling
Headphones of MDR-NC500D
Audio In
A/D
converter
System
controller
DSP
Digital
equalizer
Digital block
DNC software
engine
D/A
converter
A/D
converter
Detection
microphone
Headphone
amplifier
Driver unit
Microphone
amplifier
High-speed A/D,
D/A converter