Here is a spectrogram of me singing a very low descending figure with the combined vocal and ventricular folds, as used in Tuvan kargyraa and Tibetan chant. There was no intent other than to see how low I could go on that particular day.

The lowest frequency at the beginning of the descent it about 55 Hz, or A1. The lowest frequency just before 12 seconds is about 33 Hz. C1 is 32.7 Hz. Of course, the volume is minimal at such low frequencies.

There were no sonic effects used except a small bit of compression to control the levels. I used a RODE NTK large-diaphragm tube condensor microphone into a JoeMeek preamp, run clean, and routed via balanced line into a MOTU 828. The signal was routed via FireWire into a Mac G4 running Digital Performer 3.11. No eq was used. Spectrogram was made with Amadeus II. The AIF file was converted to 256k mono MP3 with ITunes 4.2.

Click the pic to hear a high-quality (256k) MP3. Note: many speakers or headphones can not reproduce sounds this low.