What you need to measure
A test tape or record with a 3000 or 3150 Hz tone and a compatible macOS audio input: built-in line input or a USB interface. Test media and the audio interface are not included.
Getting started
Select the input at the bottom of the window, play the tone and press the start button. On the first measurement macOS asks for microphone access, which is required to receive the input signal. Wait at least 10 seconds for the measurement windows to fill.
The Demo switch in the header shows the meter without any equipment: a synthetic tone goes through the real measurement chain.
If no readings appear
Check that the right input is selected and that the level in the header moves. The status “Tone outside ±5% of nominal” means the frequency is too far from 3000 or 3150 Hz: with a large speed error, select the nominal tone manually. If the app sees no signal, check the microphone permission in macOS System Settings.
Questions
Email cto@iswift.ru with your Mac model, macOS version and audio interface. We answer by email.