See what you're blocking: Quilence's spectrum analyzer

Here's a scenario. You're in a coffee shop. It's noisy. You open your noise app and pick a preset. Maybe it helps. Maybe it doesn't. You adjust the volume. Guess again.

The problem is you're working blind. You don't know what frequencies are in the room. Is it mostly low-frequency HVAC rumble? High-pitched espresso machine whine? Mid-range conversation? Without knowing what you're trying to mask, you're just guessing.

Quilence has a built-in spectrum analyzer. It uses your iPhone's microphone to capture ambient sound and displays it as a real-time frequency breakdown across 10 bands — from 20 Hz to 17 kHz.

You can see exactly where the noise in your environment lives:

• Low rumble (traffic, HVAC, refrigerators) shows up in the 20 to 125 Hz bands
• Speech and conversation lights up the 250 Hz to 2 kHz range
• High-pitched sounds (electronics, espresso machines) appear in the 4 to 17 kHz bands

Once you can see the problem, the solution becomes obvious. Boost the EQ bands that match the ambient noise. Leave the others alone. You're masking precisely, not carpet-bombing every frequency.

The technical details, if you're curious.

The analyzer uses a 2048-point FFT (Fast Fourier Transform) at 48 kHz sample rate, giving a frequency resolution of about 23 Hz per bin. It auto-calibrates when you first enable it, measuring the noise floor for about a second so it can distinguish signal from silence.

The display uses smoothing coefficients (attack: 0.9, release: 0.85) so the bars move naturally rather than flickering. There's also peak hold with decay, so you can see the loudest recent level in each band.

All processing happens on-device. Nothing is recorded, stored, or transmitted. You can enable and disable the analyzer at any time without affecting playback.

To use it:

1. Open Quilence and go to Settings
2. Enable "Spectrum Analyzer"
3. Grant microphone permission when prompted
4. The analyzer appears in the main view
5. Look at which bands are lighting up (those are the frequencies in your environment)
6. Boost those same bands in the EQ to mask them

It's a small feature, but it turns noise masking from guesswork into precision.