Having extracted my iPhone’s VoiceMail recordings, I reviewed them and they sounded boomy – from room resonance. The best audio enhancement app I know is iZotope RX2, which I have for Windows 7. Windows 7 was run within a virtual machine under Parallels within Mac OS. I allowed this Windows to read, but not write, Mac OS files.
- The first enhancement was a parametric EQ
- Settings: frequency 274Hz, gain -21dB and Q=1.
- The result sounded better and looked more even in the spectrum analyzer, which prior to that “glowed” around 300Hz.
- The next enhancement was Denoiser
- Settings: Advanced, Algorithm D (best, slowest), defaults (including -12dB reduction)
- Not quick – not much faster than real-time as compared to the recording.
- Finally, following this “tonal & broadband attenuation” processing, some amplitude processing in terms of dynamic range compression and overall gain.