Synopsia Apps

This app generates white, pink and red noiseand lets you make subtle adjustments to noise color (spectraldistribution). It's stable, lightweight, and plays well with thephone's OS and other audio apps, and the UI is simple andfunctional. It does not play any pre-recorded sounds. This is it ina nutshell. For more detailed information, read on.WHAT IS IT FOR?Use Noise Machine with a pair of earphones to mask distractingand annoying sounds and become at peace with the world. Loudconversations at a coffee shop where you are trying to read, cryingbabies on planes, background music that doesn't agree with yourtaste and a many other noises get into your brain and have to beprocessed. All of these sounds have certain patterns and aren'ttruly random in the mathematical sense. When you are tired orirritable or are getting too distracted, you can let your brainrest by masking these sounds with noise that doesn't have anoticeable pattern. This works remarkably well even at moderatevolumes, and you will be able to concentrate or relax much moreeasily in noisy environments. Even tinnitus can be masked this way.Noise Machine can also be used with a speaker to help put babies(and adults) to sleep. If you intend to stay awake, it's best touse it with headphones or earphones. That way, at least if youpicked the right type of noise and the earphones are comfortable,you will quickly stop noticing it; with speakers, every time youmove your head, your perception will change, and you will bereminded of the noise, which defeats the purpose. There are alsosome technical uses, such as testing speaker polarity.NOISE COLORThe terms "white" and "pink" noise refer to random signals withdifferent spectral distributions. In white noise, the noise energydensity is constant throughout the frequency spectrum (at least inthe range of interest). This is similar to white light, hence theterm "white noise". In pink noise, the lower-frequency componentsare stronger, and the noise energy density is the same in everyoctave (or decade, or any logarithm of frequency). This is alsoknown as 1/f noise. Similarly, in pink-colored light, thelower-frequency, longer-wavelength, redder components arestronger.A more general case is 1/f^α. The value of α=0 corresponds towhite noise, or flat frequency spectrum, as described above; α=1corresponds to pink noise, or -3dB/octave frequency dependence,also as described above (in different words); α=2 to "red" or"brown" noise (which refers to Brownian motion rather than thecolor brown), or -6dB/octave frequency dependence. In this app, thealpha value may be adjusted from 0 to 2 in small increments.LOOPINGOptionally, the sound may be played in a loop, which reduces thealready modest CPU and battery usage by only generating the noiseclip that's long enough to fill a loop (at the expense of usingmore RAM to store it, which normally is not a problem). Theplayback is gapless. If the loop is too short, the pattern becomesnoticeable, which creates a distraction, but even the shortest loopsetting (1 minute) should be long enough. The longest setting isdetermined by the amount of memory available to the app (typically5 minutes). If you think you can still hear a pattern, or needcontinuous random signal generation for some other purpose, or wantthe app to use as little RAM as possible, you can turn the loopoff.USE OF THIRD-PARTY WORK- A modified version of the pink noise generator class,originally written by Sampo Niskanen, distributed under the BSDlicense- Modified Android robot image and images fromhttp://www.iconarchive.com/, used according to the Creative CommonsAttribution License 3.0PERMISSIONSREAD_PHONE_STATE -- used to pause the noise sound during phonecalls.