Voice acoustics
The source-filter model: The glottis as a source of sound. The vocal tract and its frequency response. Vowels and consonants. Source-filter interactions. Vocal registers and mechanisms. Tract resonances. Resonance tuning. Harmonic singing. The singers formant.

Hearing Sensitivity
An on-line test of your own hearing sensitivity as a function of frequency. ISO standards 

What is a formant
Peaks in the spectral envelope of the voice (or other sounds). Resonances that produce these. Filters that model them. Which of these is a formant?

Rate pitch and place pitch
Fearn R and Wolfe J (2000) 'Relative importance of rate and place: Experiments using pitch scaling techniques with cochlear implant recipients'. Annals of Otology, Rhinology & Laryngology, https://doi.org/10.1177/0003489400109S1221