SPLnFFT Noise Meter vs Vibration analysis

SPLnFFT is a sound level meter (noise meter) for your iPhone or iPad with many advanced features: frequency analyzer, frequency meter, test signal generator, dosimeter, ... This soundmeter App is the only one for iOS recommended by the "Laborers' Health and Safety Fund of North America". Here are extracts from other reviews: "our favorite sound measurement app" SafetyAwakenings.com "SPLnFFT is comprehensive, easy to use" TapeOp.com You will find more reviews here: https://www.facebook.com/SPLnFFT For daily use, a very simple interface displays the level of exposure: if orange or red, protect your ears ! Professional users will take advantage of a wide range of accurate and reliable measurements: Leq, peak, L10, L95, taktmaximal, frequency analysis, histogram, dosemetering, ... A&C weightings are compliant with ANSI® S1.42 standard. "468" refers to ITU-R 468-4 *** Some KEY INFORMATION *** : - you absolutely need to allow access to microphone to use this App - screen rotation must be un-locked - there are built-in help messages (speech bubble). Need more ? Contact us !: email, blog, Facebook,... - do not expect to measure as low as 0dB(A) in a quiet room, for these 2 reasons: 30-130dB(A) is the standard usable range for sound level meters and anyway a standard quiet room is around 30dB(A) whereas a typical anechoic chamber is 10 to 20dB(A) Top digital display is for measurement of sound power in 'slow' mode (averaged on 1s). Central analog display is for 'fast' mode (averaged on 1/8th s). But it can display 'slow' mode as well on request: just click on 'fast' label. Peak and average values are displayed below and are held until you touch the 'reset' label. The videos on Youtube reveal more details. Bottom view is a real time FFT (frequency analysis). You will notice that predominant frequency and next one are highlighted. Their frequencies and relative power are displayed on the right. If your input signal is a pure tone then this App will lock on its frequency and display a very accurate result. Green line is the result of a real time FFT done with 1024 points. Purple line is the averaged FFT (exponential filtering done on power of each frequency). Blue line is a copy of what the purple line was when the user froze the display the last time. A test tone at 1kHz or a white noise or a pink noise can be generated and sent to right and/or left outputs (select the type you want in BEEP tab). This FFT view - more precisely an upsized version of it - can be exported as a picture in your own photo library, using the camera button (when display is frozen only). This picture can be exported in a mail as well. The display can be flipped upside-down to ease reading: just rotate your iPhone while holding it vertically. As for ALL sound meters (thus including this one and all others at any price), calibration is suggested if you want to reach extreme precision. This is enabled in this App thanks to a slider to apply some compensation and to three non volatile memories (choice to be made in MIC. tab). How to ? For calibration, you need and external reference, either a calibrated sound meter, or a calibrated noise source. Note as well that the tiny embedded loudspeaker cannot reproduce extreme frequencies. Thus if you want to hear a real white or pink noise, you will need to use a quality headphone or HiFi system. This App was designed seriously for our own needs, by a signal processing expert, and is regularly updated to maintain accuracy and reliability. ***** Any comment, any feedback ? Click on 'support' in iTunes: there is a blog for this. You can even contact us directly by email or through the dedicated FaceBook page (note 'send email' top right) *****

The application analyzes the data from the phone's accelerometer and builds a vibration spectrum. This allows the evaluation of not only the strength and frequency of the vibration, but also the speed of rotation of various mechanisms: fans, motors, various rotating components; since the vibration frequency often (but not always) coincides with the frequency of rotation. The application will be useful in determining the quality of fans and motors, in determining whether their actual parameters coincide with the ones declared by the manufacturer, it will find its uses in monitoring of malfunctions (e.g. in bearings) or while testing the quality of assembly and balancing of the homemade mechanisms with rotating parts. Do not expose your iPhone to an excessive vibration, as it may break. If the analyzed vibration is too strong, use a foam material pad, or put your iPhone at a distance where the force of the vibration is not dangerous to your device. In addition to decreasing vibration for the iPhone, a foam pad improves contact between the iPhone and the vibrating part, which makes the transmission of vibration more accurate and produces better results. BE SURE TO READ THE EXAMPLES OF THE VIBRATION SPECTRUM ANALYSIS AT THE APPLICATION WEB SITE (usefulmobileapps.com). Features of the full version of the application: • The choice of units of measurement. X-axis: Hz or RPM. Y-axis: g, m/s², ft/s², mm/s, in/s (ips), mm, mil, dB(A), dB(V). • FFT size (for built-in accelerometer): 64, 128, 256, 512, 1024, 2048, 4096 (data collection time from 0.64 sec. to 40 sec.). For an accelerometer connected to the headphone jack FFT size from 2048 to 131072. For Bluetooth-accelerometer FFT size from 512 to 32768. • Linear and logarithmic frequency scale. • Linear frequency scale with maximum details (there is a choice for the displayed frequency range). • Peak frequency detection. • Values of any point (for frequency scale and sound wave (at maximum detail)). • Selecting which axis of the accelerometer is to collect data. • Octave bands (1/1,1/3,1/6,1/12). • Window functions (Blackman, Hamming, Hann (Hanning), Blackman–Nuttall, Gaussian, Flat top). • Peak hold. • Exponential spectrum averaging. • Taking a screenshot by lightly touching the screen. • Root mean square (RMS, for vibration) or average value (AVG, for absolute values) for vibration wave. Values are calculated only for data displayed on the screen. • Calibration of the built-in accelerometer. Need EXCLUSIVELY for measuring absolute acceleration values (gravitational acceleration). To activate the settings, turn on the "Vibration wave" mode and turn off the "Only fluctuations" mode. The parameters of the accelerometer depend on the temperature and voltage of the battery, and may change over time. To obtain stable values, the accelerometer should work for several minutes. • Saving the measurement results in the application. Files with saved data (SavedData_[date]_[time].txt) can be copied to a desktop/laptop computer or transferred to another iPhone using iTunes. • Export data to a text ("Y=[y1 y2... yn]", "y1;y2;... yn", "x1;y1\nx2;y2;...") or WAV file. Number of points is adjusted via "FFT size". To export octaves, use "x1;y1\nx2;y2;...". • Accelerometer connects to the headphone jack (measurement range from 5 Hz to 24000 Hz). • A stroboscope for an external accelerometer (the feature was proposed by Todd French from Los Angeles, California). • Bluetooth accelerometer. When converting acceleration into speed or displacement, at 0-5 Hz frequencies noise starts prevailing over vibration peaks, which is why such frequencies are disregarded when doing the conversion. Should vibration frequency exceed 50 Hz, the peak will be recorded at an incorrect frequency, and hence speed or displacement will not be calculated correctly. Unrealistically high speed or large displacement may be a sign of this kind of false frequency.