Spectroid

Carl Reinke

About this app

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.

Ratings and reviews

Seems to work very well, very stable and precise. However, you don't know if the source audio speaker and reception mic produce said audio accurately or not. No way to know for sure. Even with whatever source you start with, you still have to trust the author it is what they say. Eg: Said audio on internet is 1150 hz. After played on phone and picked up with another phone, app says 1152 hz. However very steady. You would have to be in a sound studio for something better!

This is the best STFFT/FFT app out there on Apple or Android. The ability to change most important settings if you know what you're doing, though it's set up great out of the box. I like for the colormap/spectrogram it does it in chunks for best resolution. The only thing I find myself wanting is the ability to see what the peak level is after pausing. I can only get a cursor for the spectrum the moment it was paused. Small complaint for a great great app.