Sony MDR-NC300D Operating Manual

Noise Canceling Headphones

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MDR-NC300D

4-145-681-21(1)

Contents

1. Introduction ............................................................................................................................................................................................................................... 3

2. Outstanding Noise Canceling Performance ..........................................................................................................................................................................

2-1 Principles of Noise Canceling Mechanism ....................................................................................................................................................................

2-2 DNC Software Engine ...................................................................................................................................................................................................... 6

2-3 Automatic AI Noise Canceling Function ....................................................................................................................................................................... 8

2-4 Noise Canceling Optimization ...................................................................................................................................................................................... 10

3. High Quality Sound Technology ..........................................................................................................................................................................................

3-1 High Quality Sound by Digital Sound Enhancer .......................................................................................................................................................

3-2 S-Master Full Digital Amplifier..................................................................................................................................................................................... 16

3-3 Large 16 mm Dynamic Driver Unit ............................................................................................................................................................................. 17

4. Wearing Comfort ....................................................................................................................................................................................................................

4-1 Vertical In-The-Ear Headphones ..................................................................................................................................................................................

4-2 Hybrid Earbuds in 7 Sizes ............................................................................................................................................................................................. 19

Appendix: Total Noise Suppression Ratio .................................................................................................................................................................................

4 4

12 12

18 18

1. Introduction

Quiet surroundings are as important to the quality of sound reproduction as choosing the right audio equipment. But in today’s world, your actual listening environment, especially when using a portable music device, is likely to be far from ideal with exposure to all kinds of noise. Since 1995, Sony has pursued the ideal listening environment through the development of noise canceling headphones and we have succeeded in creating the ultimate noise canceling ear receivers using digital signal processing. This pamphlet describes the features of the MDR-NC300D headphones in terms of the technologies – Sony’s acoustic technology, signal processing technology and circuit technology – that have been built into the design of the headphones.

Features of the MDR-NC300D digital noise canceling headphones

Outstanding digital noise canceling performance

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High-quality sound design

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Excellent wearing comfort

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2. Outstanding Noise Canceling Performance

2-1 Principles of Noise Canceling Mechanism

The MDR-NC300D headphones are equipped with a feed-forward noise canceling (NC) mechanism which cancels noise near the eardrum by estimating what kind of noise it will be when it reaches the eardrum based on the ambient noise collected by the noise detection microphone, and generating an inverted sound waveform.

As shown in the figure, the noise canceling performance greatly depends on the efficiency and precision of the NC circuit to generate the noise canceling waveform.

The NC circuit uses the newly developed integrated DNC processor <CXD9952GR>. Compared with the previous analog type, it boasts excellent noise canceling performance and outstanding sound quality.

Leaked noise near eardrum

Noise

Added in space near eardrum (noise canceling)

Inverted-phase noise canceling waveform generated by NC circuit

Detection microphone

Driver unit

Newly developed integrated DNC processor

circuit

2-2 DNC Software Engine

Sony’s unique digital noise canceling technology and high quality audio processing technology come together in the Integrated DNC processor to maximize the merits of digital processing, as shown in the figure.

The noise picked up by the noise detection microphone is digitalized by the A/D converter, and the optimal canceling signal is generated through high-speed, high-precision digital filter processing by the DNC Software Engine at the heart of the processor.

After audio enhancement processing by the Digital Sound Enhancer (see page 12) via the A/D converter, the music signal from the media player is added to the noise canceling signal in the DNC Software Engine.

The added signal is faithfully reproduced by the S-Master Full Digital Amplifier (see page 16), enabling high noise canceling efficiency and dynamic music reproduction.

[Merits of digitalization]

DSP

CXD9952GR

In principle, computation is not affected by external electrical noise

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Analog Digital

NC circuit

S-Master

Digital Amplifier

Noise detection microphone

A/D converter

High precision and no variation

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Complex shapes not possible with analog filters are possible with

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digital filters

Analog Digital

Response

Frequency

Response

Frequency

Driver unit

DNC Software Engine

Digital Sound

Enhancer

AI Noise Analyzer

A/D converter

Walkman and other AV devices

2-3 Automatic AI Noise Canceling Function

The characteristics of ambient noise vary depending on the situation. For example, the characteristics of ambient noise on a plane, on a bus or a train, or in an office environment are different.

The AI Noise Analyzer inside the processor constantly monitors and analyzes the ambient noise. This function selects in real time the most appropriate of the noise canceling modes provided by the headphones (Mode A: low to midrange frequency NC, Mode B: ultra-low frequency NC, Mode C: wideband NC). In other words, it selects the mode that minimizes noise at the eardrum.

This advanced software function enables users to enjoy the optimum noise canceling effect automatically in any noise environment.

Typically, “Mode A: low to midrange frequency NC” effectively reduces the noise present mainly on a plane; “Mode B:

Tips

ultra-low frequency NC” effectively reduces the noise present mainly on a bus or train; and “Mode C: wideband NC” effectively reduces the noise present mainly in an office environment (OA equipment, air conditioning, etc.). The AI Noise Analyzer analyzes the actual ambient noise in t he user’s environment and selects the most effective noise canceling mode.

Noise

Noise detection microphone

[Mode A: low to midrange frequency NC] [Mode B: ultra-low frequency NC] [Mode C: wideband NC]

Noise canceling ratio Noise canceling ratio Noise canceling ratio

Frequency Frequency Frequency

AI Noise Analyzer

DNC Software Engine

Automatic analysis in real-time, Selects optimal NC mode

2-4 Noise Canceling Optimization

The shape of the human ear varies subtly from person to person. When you wear In-The-Ear headphones, there may be a very slight gap between your ear canal and the headphones depending on the shape of your ear. The size of the gap varies from individual to individual. Air leaking through this gap affects the loudness of the noise reaching your ears through the gap and this also affects the noise canceling efficiency.

Noise canceling optimization corrects individual differences in the noise canceling effect by electrically adjusting the size and spectrum of the noise canceling signal, thereby ensuring the best noise canceling effect for each individual.

NC OPTIMIZE

VOLUMESOUND MODE HOLD POWER

Air leakage through gap

Headphone

Response

Ear canal

Frequency

Noise canceling signal compensation by Noise Canceling Optimization

Wearing headphones

NC OPTIMIZE button for noise canceling optimization

3. High Quality Sound Technology

3-1 High Quality Sound by Digital Sound Enhancer

While the headphones offer exceptional noise canceling performance, the newly developed Digital Sound Enhancer delivers clear, natural sound. The digital equalizer ensures high quality music reproduction and provides three sound modes suited to the environment and music source.

Digital Equalizer

The acoustical design of noise canceling headphones generally emphasizes low frequency in order to maximize the effect with limited electric power, but this impact on the quality of the reproduced sound. To solve this problem, a digital equalizer is provided on the audio input side.

The digital equalizer suppresses the impact on the sound quality and delivers high quality sound that gives full play to the intrinsic performance of the driver unit.

By applying the high-precision, high-sound quality digital equalizing technology accumulated through Sony’s AV amplifiers and Hi-Fi audiovisual apparatus and adopting the newly developed computation method optimized to the system, it is possible to reproduce a music source with a sense of realism from deep bass to smooth highs.

Characteristic of acoustical system Characteristic of digital equalizer Total characteristic

Desired

Response

Frequency Frequency Frequency

Response

characteristic

Three sound modes

Three sound modes suited to the characteristics of the music source ensure easy listening in any noise environment.

 NORMAL: This mode maximizes the merits of the noise canceling headphones to produce clear, natural sounds.

 BASS: This mode boosts the bass sounds that give punch to modern dance music.

 MOVIE: This is the sound mode suited to an AV sound source with wide dynamic range, such as a movie. Compression processing increases the volume of quiet sounds such as conversation and reduces the volume of loud sounds like explosions, thereby adjusting the overall volume to a listener-friendly level. Moreover, dialog is made much easier to hear by slight emphasis of the core midrange frequency, ensuring clear, natural sounds even on a train or plane or in other noise environments.

Explosion

Human voice range

Input signal

Dialog

Loudness

Whisper

Signal processing flow

Output signal

Compression



Compression effect

Explosion

Dialog

Whisper

Appropriate volume

Noise

Movie mode (Image)

Loudness



Midrange frequency emphasized

Frequency

3-2 S-Master Full Digital Amplifier

LPF

The headphones are equipped with Sony’s retuned S-Master full digital amplifying technology. Digitization right until output ensures faithful sound reproduction to a degree not achieved with analog amplifiers.

Digital signal

S-Master S-Master

Digital logic processor Digital power amplifier

Digital waveform data Audio pulse signal Analog signal

S-Master power amplifier configuration

3-3 Large 16 mm Dynamic Driver Unit

A large 16 mm dynamic driver unit is used as the closed ear receiver.

In addition to the improved canceling of loud/ultra-low frequency environmental noise, this makes the most of the merits of wideband regeneration and the broad dynamic range to produce clear, natural sounds with a wide, balanced frequency range.

13.5 mm driver unit 16 mm driver unit

Integrated Structure of Driver Unit

For the sake of miniaturization, the driver unit has been integrated with the casing. As well as eliminating unwanted air leakage from the gaps between components, this has reduced unwanted vibration and attained a smooth response in the low range.

Conventional unit (MDR-NC22)

MDR-NC300D

4. Wearing Comfort

4-1 Vertical In-The-Ear Headphones

The introduction of the large 16 mm driver means that the headphones are worn with the driver positioned at right angles to the ear canal, enabling rich bass sounds to be enjoyed with no stress on the ear.

4-2 Hybrid Earbuds in 7 Sizes

The hybrid silicone earbuds use silicone in a combination of two hardnesses. The hard core maintains the shape of the sound exit and prevents deterioration of sound quality caused by crushing of the tip. The soft exterior allows better molding to the ear canal, providing a secure fit and wearing comfort for extended listening. Seven types of earbud are provided to suit different shapes of ear.

Section of earbud

Low hardness silicone

High hardness silicone

High

Height

Low

 

Earbud size

Small  Diameter  Large

– ML

S (orange)

SS (red)

(blue) M

(green) MS

(yellow)

LL (purple)

L (light blue)

–

Appendix: Total Noise Suppression Ratio

Previously, only the sound pressure loss at a specific frequency was indicated as the canceling performance. However, Sony has proposed a unit showing the loss of sound “energy” as a closer expression of the listener’s impression.

The total noise suppression ratio (TNSR) of noise canceling headphones is expressed by the following formula.

TNSR = 10 log (P/P P0 = Energy of sound observed at the ear when not wearing headphones

P = Energy of sound observed at the ear when wearing headphones

* The above energy of sound measurements are weighted.

TNSR is the value measured using the noise signal based on a broad spectrum. As compared with the method of measuring the noise canceling ratio at one frequency, TNSR enables the canceling performance in the actual usage environment to be more objectively evaluated. Moreover, the canceling performance in each noise environment can be evaluated using the signals to simulate the spectrum distribution of real-world noise such as a plane or train.

)

20 50 100 200 500 1k 2k

Plane noise When wearing headphones

Energy

Frequency

(NC ON)

This area is equivalent to the canceled noise energy

Total Noise Suppression Ratio (Typical values)

Plane Mode A

Train/Bus Mode B

Office Mode C

18.0 dB (98.4 %) 18.4 dB (98.6 %) 16.8 dB (97.9 %)

Based on Sony’s noise source simulations

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Table des matières

2. Effet anti-bruit exceptionnel ....................................................................................................................................................................................................

2-1 Principes du mécanisme anti-bruit ................................................................................................................................................................................

2-3 Fonction anti-bruit AI automatique ............................................................................................................................................................................... 8

2-4 Optimisation de l’effet anti-bruit ................................................................................................................................................................................... 10

3. Technologie audio de haute qualité ......................................................................................................................................................................................

3-1 Son de haute qualité grâce au Digital Sound Enhancer .............................................................................................................................................

3-2 Amplificateur numérique intégral S-Master ............................................................................................................................................................... 16

3-3 Grands transducteurs dynamiques de 16 mm ............................................................................................................................................................17

4. Confort d’utilisation ...............................................................................................................................................................................................................

4-1 Ecouteurs intra-auriculaires verticaux .........................................................................................................................................................................

4-2 Oreillettes hybrides en 7 tailles...................................................................................................................................................................................... 19

Annexe : Taux de suppression totale du bruit

........................................................................................................................................................................... 20

4 4

12 12

18 18

1. Introduction

Un environnement silencieux est aussi important pour la qualité de la reproduction audio que le choix de l’appareil audio adapté. Cependant, dans le monde moderne, votre environnement d’écoute, en particulier lors de l’utilisation d’un appareil audio portatif, est généralement loin d’être idéal et vous expose à tous types de bruits. Depuis 1995, Sony tente de procurer un environnement d’écoute optimal en développant des écouteurs anti-bruit. Ainsi, nous avons réussi à créer les récepteurs anti-bruit par excellence grâce au traitement des signaux numériques. Cette brochure décrit les caractéristiques des écouteurs MDR-NC300D en ce qui concerne les technologies – technologie acoustique, de circuits et de traitement des signaux Sony – intégrées dans la conception de ces écouteurs.

Caractéristiques des écouteurs anti-bruit numériques MDR-NC300D

Effet anti-bruit numérique exceptionnel

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Conception audio de haute qualité

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Excellent confort d’utilisation

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2. Effet anti-bruit exceptionnel

2-1 Principes du mécanisme anti-bruit

Les écouteurs MDR-NC300D sont dotés d’un mécanisme anti-bruit (noise canceling, NC) prédictif qui anticipe le type de bruit et l’élimine avant qu’il atteigne le tympan, en fonction du bruit ambiant recueilli par le micro de détection du bruit ; cela en générant une forme d’onde acoustique inversée.

Comme illustré dans la figure, l’effet anti-bruit dépend considérablement de l’efficacité et de la précision du circuit NC pour générer la forme d’onde anti-bruit.

Le circuit NC utilise le processeur DNC intégré développé récemment <CXD9952GR>. Par rapport au type analogique précédent, il permet d’obtenir une réduction remarquable du bruit et une qualité sonore exceptionnelle.

Fuite de bruit à proximité du tympan

Bruit

Ajouté dans l’espace proche du tympan (fonction anti-bruit)

Forme d’onde anti-bruit à phase inversée générée par le circuit NC

Transducteur

Micro de détection

Processeur DNC intégré développé récemment

Circuit

2-2 DNC Software Engine

La technologie anti-bruit numérique unique et la technologie de traitement audio de haute qualité proposées par Sony sont réunies dans le processeur DNC intégré pour optimiser les atouts du traitement numérique, comme illustré dans cette figure.

Le bruit recueilli par le micro de détection du bruit est numérisé par le convertisseur audio-numérique et le signal d’annulation optimal est généré via un traitement de filtrage numérique à grande vitesse et de haute précision réalisé par le DNC Software Engine qui se trouve au cœur du processeur.

Après le traitement d’amélioration audio effectué par le Digital Sound Enhancer (voir page 12) via le convertisseur audionumérique, le signal de musique provenant du lecteur multimédia est ajouté au signal anti-bruit dans le DNC Software Engine.

Le signal ajouté est fidèlement reproduit par l’amplificateur numérique intégral S-Master (voir page 16), assurant ainsi une haute efficacité de l’effet anti-bruit et une reproduction dynamique de la musique.

[Avantages de la numérisation]

DSP

CXD9952GR

En principe, le calcul n’est pas affecté par les bruits électriques externes

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Analogique Numérique

Circuit

Amplificateur numérique

S-Master

Micro de détection du bruit

Convertisseur audio-numérique

Haute précision et absence de variation

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Les filtres numériques permettent d’obtenir des formes complexes, ce



qui est impossible avec les filtres analogiques

Analogique Numérique

Analogique

Réaction

Fréquence

Réaction

Numérique

Fréquence

Transducteur

DNC Software Engine

Digital Sound

Enhancer

Analyseur

de bruit AI

Convertisseur audio-numérique

Walkman et autres appareils AV

2-3 Fonction anti-bruit AI automatique

Les caractéristiques du bruit ambiant dépendent de la situation. Par exemple, les caractéristiques du bruit ambiant sont différentes dans un avion, un bus ou un train, ou encore dans un environnement de bureau.

L’analyseur de bruit AI situé à l’intérieur du processeur contrôle et analyse le bruit ambiant. Cette fonction sélectionne en temps réel le mode anti-bruit le plus approprié proposé par les écouteurs (Mode A : NC de basses et moyennes fréquences, Mode B : NC de fréquences ultra-basses, Mode C : NC à large bande). En d’autres termes, il détecte le mode qui minimise le bruit au niveau du tympan.

Cette fonction logicielle avancée permet aux utilisateurs d’obtenir automatiquement un effet anti-bruit optimal dans tout environnement bruyant.

Conseils

Généralement, « Mode A : NC de basses et moyennes fréquences » réduit de manière efficace le bruit principalement présent dans un avion, « Mode B : NC de fréquences ultra-basses » réduit de manière efficace le bruit principalement présent dans un bus ou un train et « Mode C : NC à large bande » réduit de manière efficace le bruit principalement présent dans un environnement de bureau (ordinateur, climatisation, etc.). L’analyseur de bruit AI analyse le bruit ambiant effectivement présent dans l’environnement de l’utilisateur et sélectionne le mode anti-bruit le plus efficace.

Bruit

Micro de détection du bruit

Analyseur de bruit AI

Analyse automatique en temps réel, sélection du mode NC optimal

[Mode A : NC de basses et moyennes fréquences]

Taux d’annulation du bruit Taux d’annulation du bruit Taux d’annulation du bruit

Fréquence Fréquence Fréquence

[Mode B : NC de fréquences ultra-basses]

DNC Software Engine

[Mode C : NC à large bande]

2-4 Optimisation de l’effet anti-bruit

La forme de l’oreille humaine varie de manière subtile d’une personne à l’autre. Lorsque vous portez les écouteurs intra-auriculaires, un léger espace peut être présent entre le canal auriculaire et les écouteurs, selon la forme de l’oreille. La taille de l’espace varie d’un individu à l’autre. La fuite d’air via cet espace affecte le volume sonore du bruit qui parvient aux oreilles et cela réduit l’efficacité de la fonction antibruit.

L’optimisation de la fonction anti-bruit corrige les différences individuelles en termes d’effet anti-bruit en réglant électriquement la taille et le spectre du signal anti-bruit, garantissant ainsi un effet anti-bruit optimal dans chaque situation particulière.

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