The and have similar low first formants, whereas has a higher formant. A 16-band vocoder with Formant Shift function is also available. Linguolabials can be distinguished from bilabials and alveolars acoustically by formant transitions and nasal resonances. The second formant, F2, corresponds to vowel frontness. The first formant, abbreviated "F1", corresponds to vowel openness (vowel height). The variability of formant frequencies among individuals decreases with age. The higher the frequency of the first formant, the lower (more open) the vowel. Formant synthesis does not use human speech samples at runtime. The eSpeakNG provides two different types of formant speech synthesis using its two different approaches. Acoustically, both tend to dampen the first formant with whispery voice showing more extreme deviations. Based on Formant synthesis, it also has FM synthesis capabilities similar to the DX range. It uses a formant synthesis method, providing many languages in a small size. These wave forms include Sine, All1, All2, Odd1, Odd2, Res1, Res2, and Formant. The FS1R also contained an additional wave form called the Formant wave form. The second formant, giving -lo(w), -l(e)y, etc.