CLL Audio Tools
SPL, spectrum, tuner & more
Only for iPhone
Free
iPhone
On-device audio tools for engineers and musicians: SPL meter, spectrum analyzer, tuner, signal generator, metronome, and quick studio calculators.
CLL Audio Tools puts the everyday measurement and practice tools of a studio or live-sound kit on your iPhone. Everything runs on the device: no account, no ads, no tracking, and audio is never recorded or uploaded.
MEASURE
• SPL Meter — A- and C-weighted sound level estimates with Fast and Slow response. Add an optional reference calibration against a trusted meter to track session LAeq, LASmax and a NIOSH-rule dose estimate.
• Spectrum Analyzer — live FFT spectrum and 1/3-octave RTA in landscape, with held peaks, snapshots, and import of a microphone response file (.txt or .frd) for display correction.
• Tuner — note, cents and frequency with an A4 = 440 Hz reference.
PLAY
• Signal Generator — sine, white noise, pink noise, sawtooth and sweep from 20 Hz to 20 kHz, with output level in dBFS.
• Metronome — 20–300 BPM, tap tempo and four subdivisions. Keeps playing when you switch apps or lock the screen.
CALCULATE
• Samples ↔ Time — convert samples and milliseconds at a selected sample rate, with common rates and quick buffer-size presets. This is one buffer's duration, not total input/output latency.
• Distance Delay — speaker-to-listener distance in meters or feet to milliseconds.
• Delay — note values in milliseconds from BPM.
• Frequency — Hz to note and cents, and back.
• dB — dBFS, dBu and dBV with a selectable reference level.
• Wavelength — wavelength and frequency at a chosen air temperature.
A note on accuracy: iPhone microphones are not certified measurement microphones. SPL readings are estimates and are not a substitute for a Class 1 or Class 2 sound level meter or for professional hearing-protection advice.
Made by Critical Listening Lab, ear training for musicians and audio engineers: criticallisteninglab.com
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
Added Samples ↔ Time to convert sample counts and milliseconds at preset or custom sample rates, with quick buffer-size presets. SPL Meter and Spectrum Analyzer now start measuring as soon as microphone access is granted on first use.
The developer, JOOSOO ALAN HAN, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- JOOSOO ALAN HAN
- Size
- 3.2 MB
- Category
- Music
- Compatibility
Requires iOS 17.0 or later.
- iPhone
Requires iOS 17.0 or later.
- iPhone
- Languages
- English and Korean
- Age Rating
4+
- 4+
- Copyright
- © 2026 Critical Listening Lab