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posted by toons at 11:40| Diary



posted by toons at 11:27| Comment(0) | お知らせ


Pink noise

Pink noise is a noise sound that the power is inversely proportional to frequency, and the energy per octave is constant. It is a noise passed through a low pass filter of -3dB/ oct for White noise. On the other hand, White noise is such that the energy of each frequency is constant, and the energy level rises at the rate of +3dB/oct when the frequency increases.

Therefore, Pink noise becomes a frequency characteristic that goes down to the right as the frequency increases. Since the energy for each constant frequency band becomes uniform, it is noise suitable for the purpose of evaluating the volume of each frequency band. Pink noise is often used for sound adjustment and measurement because the sound intensity is the same in any octave band.

Incidentally, it is said that Pink noise is the same as what is said to be "1/f fluctuation" or "1/f noise" and it is said to be close to the distribution of sound in the natural world. Since Pink noise resembles an actual music signal because it has a spectrum, you can give the sound system the same stress as the music signal.

For example, you can measure the frequency characteristics of a sound system and calibrate it using an octave band or 1/3 octave band real-time analyzer.
At this time, our Realtime Analyzer application "Audio Frequency Analyzer" and "fo-Kannon" are also available. If you play back Pink noise from your audio system, it measures the characteristic frequency spectrum by setting of LEVEL and HOLD in the 1/3 Octave mode on our app. You can see the overall frequency response result of the audio playback environment. While feedback in realtime by using this result, you can easily improve the sound quality of your audio environment.

posted by toons at 17:39| Sound





ちなみに、ピンクノイズは「1/fゆらぎ」または「1/fノイズ 」と言われるものと同じものであり、自然界の音の分布に近いと言われています、ピンクノイズは実際の音楽信号に似たスペクトラムを持っていますので,サウンドシステムに音楽信号と同様な負荷を与えることができます。

例えば、オクターブバンドまたは 1/3 オクターブバンドのリアルタイム・アナライザーを用いて、サウンドシステムの周波数特性を測定し、その較正をおこなうことができます。
当社のリアルタイム・アナライザー・アプリ"Audio Frequency Analyzer""fo-Kannon"も利用可能です。あなたのオーディオシステムにおいて、ピンクノイズをスピーカーから再生しながら、1/3オクターブモード、レベル&ホールド設定で周波数スペクトラムを測定することで、オーディオ再生環境のオーバーオールな周波数特性を詳細に観測することができます。

posted by toons at 19:54| Comment(0) | オーディオ


White noise

White noise is a wave that vibrates irregularly and usually refers to noise in the audible band.

White noise has the same amplitude at every frequency. When seeing with acoustic power in a frequency band of a fixed width, the power of frequency becomes 3 dB/oct higher as the frequency becomes higher. Also, Pink noise is a filter that attenuates White noise by 3 dB/oct per frequency. In addition, the name of "white" is because light containing all frequencies is white color.

White noise is often used in technical fields such as sound adjustment and acoustic measurement, but it is also applied in various fields in medical fields and social fields. For example, by listening to white noise, symptoms of people suffering from tinnitus are alleviated, listening to noise such as masking sounds makes it easier for people with insomnia to fall asleep, concentration of works, it has been reported that there are better effects.

In the sound-related, the broadband noise signal (White noise and Pink noise) is commonly used. In order to perform more detailed measurement evaluation and tuning, it is also used the testing signal that has the specific subdivided frequency bands like a 1/1 or 1/3 octave band noise.

We have four types of applications that can generate White noise and Pink noise. 
- "Audio Tone Generator" : This app can generate generic audio reference signal.
- "Audio Tone Generator Lite" : Simplified "Audio Tone Generator", it is a free app. It has an advertisement display.
- "Audio Tone Generator for iPad" : This app can generate generic audio reference signal ustomized for iPad.
- "Octave Band Noise Generator/Lite" : By using white noise and pink noise as the source signal, it can generate a specific noise signal divided in frequency band by 1/1 or 1/3 octave band. Any frequency band can be programmably selected and output.

posted by toons at 21:11| Sound


ホワイトノイズ (White noise、白色雑音)は不規則に振動する波のことで、通常は可聴帯域のノイズを指します。





- "Audio Tone Generator" : 汎用的なオーディオ基準信号を生成できるアプリです。
- "Audio Tone Generator Lite" : 上記の"Audio Tone Generator"を簡略化した無料アプリです。広告表示があります。
- "Audio Tone Generator for iPad" : iPad向けにカスタマイズしたオーディオ基準信号を生成できるアプリです。
- "Octave Band Noise Generator" : ホワイトノイズおよびピンクノイズをソース信号として、1/1または1/3オクターブバンドで周波数帯域分割されたノイズ信号を生成できるアプリです。任意の周波数バンドをプログラマブルに選択して出力可能です。

posted by toons at 20:29| Comment(0) | オーディオ


About environmental noise level and unit.

The sound transmitted through the air is a minute pressure fluctuation centered on the atmospheric pressure. The effective value of the variation component is called sound pressure, and the unit is Pascal (Pa).

The range of sound intensity that human beings can feel is very large, and it has a large fluctuation width of 100,000 times from 20 uPa to 20 Pa. Therefore, in order to quantify the physical size of the sound, the ratio to the minimum reference sound pressure (static pressure) is taken and its common logarithm is displayed as the sound pressure level (dB: decibel).

In the noise measurement field, the level (A characteristic sound pressure level) corrected by the frequency weight characteristic determined based on human auditory characteristics is mainly used as the noise level. Because this A characteristic matches audibility sensitivity, low frequency below 200 Hz is hardly reflected in sound pressure level.

Examples of environmental noise and the level of noise level are shown below.

130dB : Engine sound of Airplane
110dB : Horn of Car
100dB : Noise of passing train
90dB : In loud factory
80dB : In the train, Vacuum cleaner
70dB : Noisy office, Noisy street
60dB : Quiet Car, Normal conversation
50dB : Quiet office
40dB : In the library, Quiet residential area
30dB : Outskirts of midnight, Whisper
20dB : Sounds of rubbing leaves

The above can be measured as A characteristic noise level (dBA) by our application "Sound Level Analyzer PRO". However, please note that the explosion sound like aircraft jet engine sound is beyond the limit of built-in microphone measurement.

posted by toons at 18:11| Environment






130dB : 飛行機のエンジン音
110dB : 自動車のクラクション
100dB : 列車の通過時の騒音
90dB : 騒々しい工場の中
80dB : 電車の中、掃除機
70dB : 騒々しいオフィスや街頭
60dB : 静かな自動車、普通の会話
50dB : 静かなオフィス
40dB : 図書館の中、 静かな住宅街
30dB : 深夜の郊外、ささやき声
20dB : 木の葉の擦れあう音

上記は、当社アプリ”Sound Level Analyzer PRO"などで、A特性騒音レベル(dBA)として測定できます。A特性、FASTの設定で、騒音測定してください。

posted by toons at 17:48| Comment(0) | 環境・騒音



posted by toons at 21:23| Comment(0) | 日記


FAQ-A007 : How should I connect iPhone/iPad to the audio system in a signal generation app?

FAQ-A007 : How should I connect iPhone to the audio system in a signal generation app like "Audio Tone Generator" ?

[Answer] Audio signal generation application can connect to audio system by the following method.
(1) Output from 3.5mm headphone jack.
(2) Output using Lightning compatible digital audio interface.
(3) Connect with AirPlay using WiFi.

We recommend to use the Lightning' connection in (2) since the digital audio output has the highest signal accuracy and is stable as the reference signal source.
In addition, AirPlay in (3) has sound quality problems in the receiving equipment since it adopted Apple's proprietary wireless communication method. It seems to occur by wireless communication status, compatibility with connected equipment, and audio data compression algorithm. According to our user report, there is information that the sound via AirPlay may be interrupted momentarily the audio signal in the higher frequency band of over 10 kHz in the sinusoidal frequency sweep.

Applicable App : Audio Tone Generator, Audio Tone Generator Lite, Audio Tone Generator for iPad, Octave Band Noise Generator/Lite

posted by toons at 21:34| FAQ-EN