Product Information
3-280-434-02(1)
MDR-NC500D
©2008 Sony Corporation
Noise Canceling
Headphones
GB
JP
2
JP
3
JP
1
.........................................................................
4
2
........................................
5
2.1.
..........................
6
2.2.
.....................................................................
7
2.3.
..................................................................
8
3 AI
........................................
9
3.1. AI
..........................................
10
4
.............................................
10
5
.........................................
11
6
...........................................................
12
7
...............................................................
13
7.1.
..............................................................................
13
7.2.
...........................................................................
13
7.3.
.......................................................................
13
7.4. 3
...................................................................................
13
7.5.
BTL
.....................................................
13
....................................
14
1.1.
..............................................................................
14
JP
4
JP
•
•AIArtificial Intelligence
•
• SN
1
5
JP
•
•
2
1 2 3
6
JP
2.1.
NC
NC
NC NC
7
JP
2.2.
A/D DSP
DSP DNC
A/
D
DSP DSP
D/A
A/D,D/A
MDR-NC500D
Audio In
A/D
DSP
DNC
D/A
A/D
8
JP
2.3.
NC
DNC
DSP
DNC
SN
NC NC
9
JP
AI
3 AI
NC C
OA
AI
NC A
NC B
*
10
JP
3.1. AI
AI
1 AI NC MODE *
2 DSP
3
*
AI AINC
AI
4
DSP
11
JP
5
NC
AV Hi-Fi
12
JP
195 g * 10 %
* MDR-NC60
6
13
JP
7
7.1.
7.2.
7.3.
7.4. 3
3 *
1
AC 3
AC 100 V 240 V
*
2
*
1
3 2
*
2
7.5. BTL
BTL Bridged Transformer-Less
14
JP
1.1.
Total Noise Suppression Ratio :
TNSR
TNSR = 10 log (P / P
0
)
•P
0
=
•P =
*
15
JP
NC A
NC B
NC C
20.0
17.0
14.9
TNSR 20 dB
ON OFF
1
(OFF)
(ON)
TNSR
dB
•
• 25 dB A
18.0
20.3
15.0
17.1
18.3
18.9
2
GB
3
GB
GB
Content
1. Introduction .......................................................................................................... 4
2. Principle of Operation of MDR-NC500D and Its Configuration ......................... 5
2.1. Feedback Type and Feedforward Type .......................................................................... 6
2.2. System configuration of MDR-NC500D ....................................................................... 7
2.3. Advantages of Digitization ............................................................................................ 8
3. AI Noise Canceling Function ............................................................................... 9
3.1. Operation of AI Noise Canceling function .................................................................. 10
4. Specialized Driver Unit ...................................................................................... 10
5. High-Quality Sound Unique to Digital .............................................................. 11
6. Weight saving mechanism .................................................................................. 12
7. Other Features .................................................................................................... 13
7.1. Monitor function .......................................................................................................... 13
7.2. Swivel mechanism ....................................................................................................... 13
7.3. Detachable connecting cord ........................................................................................ 13
7.4. Power supply ...............................................................................................................13
7.5. High-quality sound BTL headphone amplifier ............................................................ 13
Appendix: Indication of Canceling Performance
for Noise Canceling Headphones ....................................................................... 14
1.1. Total Noise Suppression Ratio .................................................................................... 14
4
GB
MDR-NC500D is the Digital Noise Canceling Headphones, which Sony developed as the
first of their kind in the world.
For this development, Sony put in all of its acoustical analysis technology, digital signal
processing technology and transducer technology.
By digitizing the noise canceling function, we succeeded in improving the performance in
the following points which, were difficult to be addressed with the conventional analog signal
processing:
• High canceling performance
• AI (Artificial Intelligence) Noise Canceling function
• Excellent sound quality
• Higher Signal to Noise ratio
1.Introduction
5
GB
GB
2. Principle of Operation of MDR-NC500D
and Its Configuration
The noise canceling headphones make a canceling signal by analyzing with their noise
canceling circuit the surrounding noise collected by the small noise detection microphone built
in their main body.
With this canceling signal superimposed on the regenerative signal from the connected
equipment, reproduction from the driver unit reduces surrounding noise and makes it possible
to listen to music more clearly.
For the noise canceling, the following two methods are mainly used:
• Feedback type
• Feedforward type
1. Waveform of noise
(original sound)
Surrounding noise is collected by
the noise detection microphone
built in the headphones and its
signal is analyzed with the noise
canceling circuit.
2. Inverted sound
waveform
The inverted sound, which can
negate the analyzed noise, is
generated.
3. Sound waveform
canceled by
superimposition
By overlaying the original sound
with the inverted sound, the
original sound is negated. This
reduces noise at the eardrum.
Continued
6
GB
2.1. Feedback Type and Feedforward
Type
Feedback type
The noise canceling function of the “feedback type” is used in MDR-NC500D.
In the feedback type, the noise detection microphone is placed close to the ear.
By collecting noise in the position closer to the ear, a noise canceling effect with high
accuracy can be obtained.
The audio signal of noise collected by the noise detection microphone is analyzed on real
time with the noise canceling circuit (NC circuit), producing a canceling signal to always
minimize the noise at the eardrum. The canceling signal is reproduced from the driver unit.
Using this method enables the cancellation effect to be increased with the changing
environmental noise addressed.
Feedforward type
In the feedforward type, the noise detection microphone is attached outside the
headphones.
The NC circuit analyzes the noise signal collected by the noise detection microphone to
estimate what kind of sound the noise will become when it comes to the eardrum. And from
this estimated result, a canceling signal to minimize the noise is made and it is reproduced
from the driver unit.
This type enables miniaturization of the headphones since it is not necessary for the noise
detection microphone to be located near the ear where space is limited.
Feedback type Feedforward type
Noise
Driver unit
Noise detection
microphone
NC circuit
Noise
Driver unit
Noise detection
microphone
NC circuit
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