SPL (deciBel) Meter Overview


The SPL (deciBel) Meter is an advanced audio measurement tool featuring a variety of functions such as RT60, Leq, Sone, Spectrum Analyzer, Spectrogram, Chart Recorder, Signal Generator, Polarity Checker, and Mic Calibration.



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Key Features



  • 1/1, 1/3, 1/6 & 1/12 octave RTA modes

  • Leq (wideband, Octave, variable duration)

  • Sones (Loudness)

  • RT60 (wideband, Octave)

  • Peak Store

  • Spectrogram and Waterfall displays

  • Peak frequency detection

  • Impulse, Fast, Medium & Slow filters

  • Flat & A/C Weighting and film industry X Curve

  • Averaging and SPL Chart Recorder

  • Noise Criteria (NC and NR)

  • Various Signal Generators (White/Pink Noise, Sine, Square, Triangle, etc.)

  • Loudspeaker polarity checker

  • RTA Store & Load functionality

  • Hann windows for improved accuracy

  • Pinch to zoom and scroll to center features

Recent Updates (April 2019)



  1. v8.0: Load one or two stored spectrum files and display both alongside real-time data.

  2. v8.1: New Generator option to swap phase of Right stereo signal.

  3. v8.2: New Menu option "Set Resolution" for 4096, 8192, or 16384 sample lengths.

  4. v8.3: Introduction of 1/12 Octave RTA mode.

Exclusive Calibration Features


The ISO 1/3 Octave Calibration allows for correction of your phone's microphone response. Calibration discs can be adjusted to achieve a flat response, matching the overall SPL to an external meter. Additionally, save and restore calibration files for popular microphones like Dayton Audio iMM-6 and MicW i436.

Applications


Ideal for various uses including:



  • Gig measurements

  • Home theater setups

  • Acoustic analysis

  • Car audio systems

AudioTool Features


The AudioTool provides FFTs of microphone samples with reduced aliasing through Hann windowing. SPL is calculated in real-time, and spectra can be saved and displayed alongside the live spectrum.


To manage the interface:



  • Tap the screen to hide/show buttons.

  • Pinch the screen to zoom the scale.

  • Drag to move the scale.

Cursor Functionality


A pair of cursors can be displayed, allowing users to move them to any position to show SPL and time/frequency values. Cursors can be toggled in the Menu.

Polarity Checker


The Loudspeaker Polarity Checker allows users to verify if a loudspeaker is wired in phase. Connect the AudioTool output to the speaker, select "Polarity" from the signal generator screen, and check the RTA screen for results.

Noise Criteria Function


This function overlays NC contours on the 1/1 Octave RTA display, showing the current NC value in real-time.

Chart Recorder


The Chart Recorder provides a moving trace of SPL measurements over the past few minutes.

RT60 Measurements


Measure reverberation or echo in a room using the RT60 function, which can be triggered by a loud clap or Pink Noise from the AudioTool generator.

Signal Generator


The Signal Generator produces various waveforms including White and Pink Noise, Sine, Square, Triangle, and Ramp waves. It ensures randomness in noise generation through multiple cycled buffers.


Frequency accuracy is typically around 1%, with good fidelity across most audio ranges.

Additional Resources


For more detailed information, refer to the Online Manual.


Join the friendly AudioTool Discussion Group to request features, find calibration files, or report issues. Your feedback is always welcome!

Disclaimer


AudioTool's performance depends on your Android hardware and is not guaranteed to meet any audio measurement or safety standards.