Spectrum Analyzer Desktop

This RTA app supports simultaneous display of "Audio Waveform", as well as the FFT-based "Amplitude Spectrum" (frequency magnitude) and "Spectrogram" (frequency distribution over time), for audio signals input from a microphone.
(FFT: Fast Fourier Transform, RTA: Real Time Analyzer)

Features

- Supports simultaneous display of Waveform / Spectrum / Spectrogram.
- Selectable configuration of Waveform / Spectrum / Spectrogram display.
- Selectable FFT size
- Selectable Spectrum Average.
- Selectable window function
- Selectable frequency weighting (A-weighting, C-weighting, Z-weighting)
- Selectable the type of expressing the X direction (frequency) of Spectrum / Spectrogram. (Linear, Log)
- Display of spectrum peak level and peak frequency
- Peak Hold (displays held past peak values of the spectrum)
- Octave Analysis (displays the spectrum grouped into octave bands)
- Audio signal generation (4 waveform types)
- Pitch meter display
- Zoomed waveform and spectrum display
- Log output (Available in the Pro version)


Feature Details

[Screen Layout]
Select the display screen configuration.
View Num : 1, 2
View Type :
- 1 screen : Wave (Waveform) / 1D (Spectrum) / 2D (Spectrogram)
- 2 screens : W+1D (Waveform + Spectrum) / W+2D (Waveform + Spectrogram) / 1D+2D (Spectrum + Spectrogram)
Layout : Vertical (displayed vertically), Horizon (displayed horizontally)

[FFT Size]
Selectable sample count for FFT:
1024, 2048, 4096, 8192, 16384
(*4096 and above are available in the Pro version.)

[Spectrum Average]
Number of spectrum average for a display of spectrum. (init value: 1) (1, 2, 4, 8)
Higher value will make the spectrum less noisy and more smooth, at the cost of lower time resolution.

[Window Function]
Selectable window function (multiplied just before FFT) used for spectrum calculation:
- Hanning: Hanning window
- Hamming: Hamming window
- Blackman: Blackman window
- None: No window function

[Frequency Weighting]
Selectable frequency weighting (used when measuring sound pressure level with sound level meters):
- Flat (Z-weighting): No frequency correction
- dBA (A-weighting): Correction based on human hearing characteristics
- dBC (C-weighting): Wider-band, relatively flat response compared with A-weighting

[Frequency Axis Scale Type]
Selectable the type of expressing the X direction (frequency) of Spectrum / Spectrogram.
- Linear: Equal spacing
- Log: Logarithmic spacing

[Peak Hold]
Displays held past maximum (peak) spectrum values.

[Octave Analysis]
Displays spectrum data grouped into octave bands.
Division method:
- FFT: Standard spectrum display
- 1/12, 1/6, 1/3, 1 octave: Octave-band display (larger values use wider bands)
Calculation method:
- Max: Displays the maximum spectrum value in each band
- Average: Displays the average spectrum value in each band

[Pitch Meter]
Displays spectrum peak frequency as a meter and musical pitch (e.g., C3, G#4):
- Display on/off
- Accidental display selection (b / #)

[Audio Signal Generation]
Configurable generated audio signal:
- 4 waveform types: Sine, Triangle, Square, Sawtooth
- Frequency: 20 Hz - 20,000 Hz


Other

- Background color selection: Black, White
- WaveForm: Line Color (Green, Yellow, Invert), Line Width (1.0 ~ 6.0 px)
- Spectrum: Bar color (Green, Yellow, Colorful)
- Spectrogram: Colormap, Display range (-150 ~ -60 dB), Display time (4 ~ 15 sec)
- X/Y zoom and scroll display for waveform/spectrum view
- Log output (peak frequency, peak level) (Available in the Pro version)


Information

- Vertical line interval in waveform display: 2 ms
- Spectrum calculation uses the vDSP library


Most features of this app are available for free. If you purchase the Pro version via In-App Purchase, you can use the following features.
- FFT sizes: 4096, 8192, 16384 (for more precise spectrum analysis)
- Log output (saves analysis results in CSV format)