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Appendix

This tool is not a "measurement instrument"

This software is a simple signal analysis and observation tool using a PC and an audio interface. While it is useful for learning, hobbies, or initial estimations in development, it cannot be used for strict quality assurance or standards compliance testing.

Reliable Range and Reference-Only Range

What this tool excels at is observing "relative changes."

  • Reliable Use (Relative Use):

    • Relative Comparison: Confirming changes such as "whether the noise level decreased before and after a countermeasure" or "which of A and B has less distortion."
    • Operation Check: Visual confirmation of whether the signal is clipping, oscillating, or if the intended frequency is being output.
    • Troubleshooting: Identifying 50Hz/60Hz hum noise contamination or sudden glitches.

  • Reference Only:

    • Absolute Values (Voltage, Sound Pressure): Physical quantities other than dBFS (V, dBu, SPL) are merely estimated values unless corrected using a calibrated reference instrument.
    • Measurement in Minute Domains: Measurements of THD+N below -100dB or the noise floor are strongly affected by the performance limits of the PC and audio interface itself.

Troubleshooting

If you have trouble, please check the following items.

❓ No sound / No response to input

  • Power and Connection: Confirm that the audio interface is turned on and the USB cable is correctly plugged in.
  • Settings Widget: Confirm that the correct device (ASIO/WASAPI, etc.) is selected.
  • OS Shared Mode: Confirm that other recording software, browsers, or web conferencing tools are not occupying the device.

❓ Graph movement is jerky / Sound is intermittent

  • Buffer Size: Change Buffer Optimization to STABLE or ULTRA in the Settings widget.
  • CPU Load: Close other heavy applications.

❓ Screen appears to be frozen at startup

  • WISDOM Generation: On the first launch, it may take several tens of seconds to calculate "WISDOM (FFT optimization)." It is not a malfunction, so please wait.

❓ Mountain appears at a different frequency even though a 1kHz signal is being output

  • Sampling Rate Mismatch: Confirm that the sampling rate setting in MeasureLab and the setting on the audio interface side (or OS sound setting) are the same (e.g., 48kHz, 192kHz).

Finally

If the problem is not resolved, please check the basic operation again with a loopback connection (direct connection from output to input) to see if there are any connection errors or cable defects.