Acuity

About

Acuity is a properly A-weighted sound level meter, a chromatic instrument tuner, and a reference tone generator bundled into one app. Pay $4.99 once and own all three. Readings stay on the device; sessions can be exported to CSV. Acuity is honest about calibration limits and does not fake precision a phone microphone cannot deliver.

What it does

• A-weighted SPL meter with analog needle and digital readout
• Live MIN / MAX / AVG / Leq stats and a 60-second time-series chart
• Chromatic tuner with cents-off needle and adjustable A4 reference
• Reference tone generator with 100 Hz / 1 kHz / 4 kHz presets and A2-A6 notes
• No telemetry; audio samples are processed in memory and never written to disk

What you get free, and what the $4.99 unlock adds

Accuracy and limitations

Acuity reads sound through the microphone built into your phone or tablet. Phone microphones are consumer audio components, not calibrated measurement instruments, so absolute decibel values vary by hardware model and by mic obstruction (case, finger, screen protector). Use Acuity for useful relative measurements (is room A louder than room B; is a sustained noise above the level at which hearing damage is a concern over time; is this instrument in tune relative to A=440 Hz). Do not rely on it for legal, occupational-safety, medical, or regulatory compliance purposes. A built-in calibration wizard lets you apply a manual offset against a trusted reference meter if absolute accuracy matters for your use case.

Privacy at a glance

• No personal data is collected by Acuity.
• All app data is stored on your device.
• No analytics, no telemetry, no crash reporting.
• No account is required to use the app.

Read the full Acuity privacy policy or learn about account and data deletion.

Permissions Acuity requests

Microphone

To read ambient sound levels and detect instrument pitch. Audio is never recorded to storage or transmitted; samples are analyzed in memory and discarded.