チェックワンツー - ハウリングチェックアプリ

Howling that occurs at live events and performances. You can check the frequency bands where it's likely to occur before actually causing howling.

In front of the stage monitor, stay silent for 15 seconds. Then say "Check, one, two."
In about 30 seconds total, the dangerous frequency bands appear in Hz. You don't need a dedicated measurement microphone. It works with just your iPhone's microphone.

Lower the volume slightly. Change the direction of the microphone or speaker. The next steps to take also appear on the screen.

What's included:
・Monitor Check: Before the performance, it checks the frequency bands most likely to cause howling.
・Analyzer: During the performance, it displays the sound currently being output and marks the frequency bands likely to cause howling with a red line. You can also switch to a spectrogram view.
・Stereo Recording: You can record the sound from the performance or rehearsal as-is, without passing it through a compressor or limiter.
・Register Your Voice: Just read the words displayed on screen for 20 seconds.
・Metronome: Produces sound and light at a steady tempo. You can choose the time signature and the volume of the first beat.
・Tuner: Shows whether the note you play is in tune. The straighter the line, the more stable the pitch.
・Speaker Check: Plays sound in the order of left, right, left and right simultaneously, and inverted phase, as seen from the audience.
・Frequency Guessing Quiz: Two types—single note guessing and A/B comparison.
・Recording Management: You can delete recordings anytime from here.

What you can use for free:
Even for free, you can use the Analyzer, Spectrogram, Monitor Check, voice registration, Metronome, Tuner, and Speaker Check. No membership registration is required.

The full version is a one-time purchase of 1,200 yen. It's not a subscription.
・Stereo Recording …… Free version: up to 5 minutes per recording, max 2 recordings / Full version: can record performances over 5 minutes in a single file, and save as many as you want
・Monitor Check results …… Free version: up to 3 results / Full version: save as many as you want and compare with the previous time at the same venue
・Frequency Guessing Quiz …… Free version: beginner level with 6 frequency bands (250Hz–8kHz), 2 sets per day / Full version: advanced level with 21 frequency bands (63Hz–16kHz), unlimited sets per day
・A/B Comparison …… Free version: pop music only / Full version: 4 genres

iPhone, iOS 17.0 or later. No membership registration. No data collection.

Introduction page: https://check12.da-win.net/