Spectroid
Spectroid is a real-time audio spectrum analyzer with reasonable frequency resolution across the the entire frequency spectrum. 💬 FAQ 💬 Q: Why are the dB values negative? A: Spectroid uses dBFS (Full Scale) where 0 dB is the maximum power that the microphone can measure, so the decibel values are negative because the measured power is less than the maximum power. Q: Can I zoom in on the spectrum plot? A: Yes, do a two-finger pinch-to-zoom gesture. Q: Why are there discontinuities/gaps in the spectrum plot and waterfall? A: Spectroid uses multiple FFTs overlapped in frequency in order to provide better frequency resolution at lower frequencies than a single FFT. The caveat of this method is varied impulse response and minor discontinuities in frequency. The upside is that it can efficiently produce a spectrum that better matches the frequency resolution of human audio perception. It's still probably not as good as your ears though! Q: Can I export the spectrum data? A: Spectroid doesn't make your device a calibrated instrument. If you need the spectrum data then you should be using an actual spectrum analyzer rather than an app on your mobile device.
