Low Frequency Detector vs SmarterNoise Pro

"Low Frequency Detector" is an acoustic measurement tool for detecting low-frequency sounds that is hard to hear in normal situation. The human ear is not sensitive enough to low-frequency sounds. If you are exposed to noise from nearby construction or factories without realizing it, you may feel discomfort or a sense of pressure. In such cases, you can use this app to check what kind of low-frequency noise is present. Generally, low-frequency sounds is a sound wave ranging from 1Hz to 100Hz. Depending on its frequency component and sound level, the degree of influence on the human body and the noise sensation is different. This app allows you to examine the frequency component of low-frequency sounds by 1/3 octave band analysis and FFT analysis. Features: - Low-frequency power level measurement less than 100Hz (LF Level): Flat characteristic, Updating indication of measurement period 1 sec. - Power level measurement in the audible band (Leq): Flat characteristic, Updating indication of measurement period 200ms. - 1/3 octave band analysis (OCT) - FFT analysis (FFT) - Time course graph (TIME) - Snapshot (Snap) on the measurement display screen. - Report function (Report): Analysis report of a peak LF Level with TIME, OCT and FFT. - Measurement time: up to 60 sec Functions: The measurement analysis is performed in the following step. Be sure to set the measurement conditions in Step-1 once before starting the sound measurement. 1) Calibration (Calibrate): The reference signal (1kHz sine wave) is output to determine the reference noise level for the low-frequency component. If the volume level of iPhone is set to about 20-50%, the calibration will automatically adjust it to the optimum volume level for the reference signal. 2) Measurement (Measure): Analyze a power level of low-frequency sounds. - LF Level (dB): Low-frequency power level less than 100Hz. - Leq (dB): Sound power level with the frequency weight characteristic Z (Flat) of the audible band. 3) Measurement display: It can select either 1/3 octave band frequency analysis, FFT analysis or Time course graph. They are updated in real time. 4) Report: Measurement result report. It is effective when measuring for 10 seconds or more. # Time course graph: TIME - Low-frequency (LF) Level (dB): Time course graph with peak level noise level judgment (RED-very noisy, YELLOW-noisy, GREEN-normal) at the peak level. - LF max (dB): maximum dB value of low frequency. # Frequency response graph: OCT, FFT - OCT Band LF max (dB): maximum dB value in 1/3 octave band at LF max observation. - Max Level Frequency (Hz): peak frequency at LF max observation. Notes: - The sound measurement of the low-frequency range is a level difference with respect to the reference signal, which indicates the relative power level. - The reference signal is output during calibration and sound level measurement. - Do not change the volume level of iPhone after the calibration. - White line in the OCT and FFT modes indicates frequency characteristics in frequency weight correction of G characteristics. - Since iPhone's built-in microphone has a lower sensitivity on the very low frequency range, it is not recommended to measure a huge volume sound near a very loud noise source. - Since it takes a while for the observation value to stabilize immediately after the start of measurement, the maximum value is calculated from about 2 seconds later. - In the case high power of 1kHz component is included in the measured noise source, the precision of measured value by this app largely decreases. - Sudden noise or impulsive sounds are not low frequency noises in general. - The previous calibration information can be maintained internally. - The analysis results may vary due to individual differences in iPhone devices. - The authorization to access built-in microphone and Photos will be confirmed by iOS system at first access. Please visit our iOS app support page for more information.

SmarterNoise Pro is the most advanced edition of the SmarterNoise recording sound level meters. SmarterNoise Pro edition is developed especially with more advanced measurements in mind, and includes many requested features such as a frequency spectrum display, export of measurement data, A-, C- or no weighting for sound level measurement, and full screen audio mode. SmarterNoise Pro edition does not contain any advertising, and performs accurately and fast. Features: • Sound level measurement in video mode • Sound level measurement in audio mode • Sound meter snapshot camera • Record video and audio files (paid function) • Recording timer • Sound level activated audio recording • Frequency spectrum display (paid function) • Peak frequency detection • A-, C- or no frequency weighting • Export of measurement data in CSV format • Full HD (paid function), HD and VGA video resolution • Three video quality settings • Archive for saved files • Sharing of saved files • Calibration • Save location of measurement (optional) • Time and date • Continuous Leq, LAeq, LCeq value • 10 second sound level average (Leq, LAeq, LCeq) • 60 second sound level average (Leq, LAeq, LCeq) • Maximum and minimum decibel level About decibels and sound level measurement The unit for measuring sound is called a decibel. Because the decibel scale is logarithmic, a sound with an intensity that is twice that of a reference sound corresponds to an increase of about 3 decibels. The reference point of 0 decibel is set at the intensity of the least perceptible sound, the threshold of hearing. On such a scale a 10-decibel sound is 10 times the intensity of the reference sound. Highlighting this is important as already a few decibels higher or lower makes a noticeable difference in how noise is perceived. The preferred method to describe sound levels that vary over time, resulting in a single decibel value measuring the total sound energy over the period, is called Leq. It is however common practice to measure sound levels using A-weighting, which attenuates lower and higher frequencies that the average person cannot hear. In this case the value is called LAeq. A- and C-weighting The A-weighting is a standard, commonly used filter that attempts to alter the measured sound pressure levels to more closely match the perception of the human ear. A-weighting makes the sound level meter less sensitive to very high (over 8000 Hz) and low frequencies (below 1000 Hz). C-weighting also attenuates low and high frequencies, but the attenuation of low frequencies is much less severe compared to A-weighting. Calibrate: Calibrate the application using the calibration tool found in the settings menu. Phones and their components vary in quality and setup so you need to calibrate the app in order for the results to be relatively comparable. One suggestion is that you close the window and door to your bedroom or bathroom, turn off appliances, and once its very quiet calibrate the app so the reading is about 30 decibel.