Octave-band Colored Noise


"Octave-band Colored Noise" is a new sound generator app that can generate various colored noises and octave-band noises.

It can be used for various purposes such as sound masking, sound effects for tinnitus relief and sleep, reference sound source for sound equipment measurement, sound tuning, and sound insulation effect measurement for buildings.

This app generates six types of color noise signal, white noise, pink noise, brown noise, blue noise, purple noise, and gray noise.

Furthermore, octave-band noise signals of various frequency bands can be generated by processing color noise signals with the 1/1 octave-band filter.

The latest version features improved performance and revamped UI design.

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Please click on the link below to access "Octave-band Colored Noise" product page in AppStoreTM.

It will move to AppStore.

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Products Information

Version: 2.0
Release date: February 18, 2023 UTC
Size: 0.4 MB
Category: Utilities, Music, Life Style
Compatibility: Compatible with iPhone. Requires iOS 15.0 or later.
Status: Now distributing.


Noise generation : white noise, pink noise, brown noise, blue noise, purple noise and gray noise
1/1 Octave band noise generation : 8 types, center frequency - 63Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz.
Octave band noise can be selected multiple bands simultaneously. So this combined signal contains the frequency components of the multi-band.
Frequency range : 20Hz - 20kHz.


The noise signals generated by this app can be used for various purposes as shown below.

Sound masking.
Sound effects for tinnitus relief and sleep.
Sound tuning.
Reference sound source for audio equipment measurement.
Sound source for architectural acoustics measurement. (sound insulation level measurement, room sound field distribution measurement, air sound insulation of buildings, sound insulation effect of windows, etc.)

For example, octave-band noise can be applied as a sound masking source to alleviate annoying environmental noise in network meetings at the office or home work, or when you want to concentrate on your work. If you play back general white noise or pink noise, it feels rather annoying because the frequency components in its signal are very wide. By adjusting the frequency band to cover only the frequency components of the environmental noise, you can get a less annoying noise reduction effect.

As other applications, Octave band noise is also useful to adjust the characteristics of the audibility of earphones or headphones.

By selecting the pink noise and playing the 1/1 octave band noise in the order of 125Hz, 1KHz, 8kHz of the center frequency, you can determine the intensity of each frequency band on the audibility. If you know the characteristic of frequency band, you will be able to adjust the earphone in the equalizer to your favorite sound easily.

Noise Signals

This app generates Colored noise and Octave-band noise.

Colored noise includes broadband noise signals of white noise, pink noise, brown noise, blue noise, purple noise, and gray noise.

Octave-band noise is a limited frequency band noise that processed by an octave band filter from a noise signal.

Colored noise : white noise, pink noise, brown noise, blue noise, purple noise and gray noise
Octave band-pass noise : 1/1 octave-band filter, 8 bands (center frequency - 63Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz.)

Operation procedure

The basic operation procedure is as follows:

(1) Select the noise source: Tap the Noise button to select the source noise signal. The default at initial startup is white noise.

(2) Select the band pass filter: Tap the "Octave" button to select the octave band filter. The default at initial startup is no filter.

(3) Octave-band selection: When "Octave" is selected, you can tap the frequency band button to select the frequency band you want to output.

(4) Start/Stop signal output : Tap the "Start" button to start outputting the noise signal, and tap the "Stop" button to stop it. This app also works in the background.

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Octave band noise

Octave band noise is a noise signal with a specific frequency range that is passed through an octave-band filter using color noise as the source.

The octave-band filter consists of eight separate 1/1-octave bands with center frequencies ranging from 63Hz to 8kHz. Octave-band noise signals can be easily generated by selecting the required frequency band. In addition, multiple frequency bands can be selected for simultaneous output.

Octave-band filter: 1/1 octave, 8 bands (center frequency - 63Hz, 125Hz, 250Hz, 500Hz, 1kHz, 2kHz, 4kHz, 8kHz)

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White noise

White noise is noise whose amplitude is constant throughout the audible frequency range. Twice the power corresponds to a 3 decibel increase, so white noise is said to increase 3 dB per octave in power.

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Pink noise

Pink noise is filtered to give equal power per octave or equal power per 1/3 octave. The power of pink noise per Hz of bandwidth decreases by 3 decibels per octave. When pink noise is chosen for equalizing auditoriums, the real-time analyzer can be set up so that they display a straight horizontal line when they receive pink noise. It is also called 1/f noise.

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Brown noise

The power spectral density is a noise signal that drops by 6 dB per octave as the frequency rises.

For audio applications, this is also used for subwoofer phase checking and aging of mid-low range speaker units. For healthcare applications, this is also used for relaxation treatment of sleeping disorders, sound masking for environmental noise and tinnitus. It is also called Brownian noise or red noise.

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Blue noise

Power spectral density is a noise signal rising by 3 dB per octave as frequency goes up. It is also called azure noise.

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Purple noise

Power spectral density is a noise signal that increases by 6 dB per octave as the frequency rises. It is also called violet noise.

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Gray noise

It is a noise signal that shows a power spectrum close to an equal loudness curve like psychoacoustics.

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Information view

Tap the "INFO" button, it is displayed the product information and usages. Tap the "Close" button to return to the top view.


Release Note

Version 2.0 was released on February 18, 2023 UTC.
Version 1.0 was newly released on April 11, 2021 UTC.


Please be careful that continuous high-volume and high-frequency signals can damage speakers, even if your ears don't perceive them as being too loud.
When using this application with wireless communication such as Bluetooth or AirPlay, there may be cases that limitation of the playback frequency, lowering the output level and irregular noise, etc., may occur under the influence of wireless environment, communication equipment and communication state. Please note that this is not to guarantee that this application operates as configured specifications under the wireless communication.
AirPlay data transmission is a wireless communication system using Apple's proprietary audio data compression. For this, there are cases where the random sound noise is generated by radio condition and the compatibility of AirPlay connection equipments. Note that it may occur at particularly high frequency band.
This app does not support wireless control of volume/channel balance unique to wireless audio devices such as AirPods.
The octave band-pass filters are compliant with "IEC 61260:1995" and "JIS C 1514:2002".

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