In phonetics, a formant is the peak in the spectral envelope and its frequency components of the human speech and singing. The resonances that create formants happen in the vocal tract. We are able to distinguish vowels one from the other thanks to the energy that is accumulated in specific sections of the spectrum. The order of the formants from lowest to highest is expressed in F_1,F_2,F_3 , etc.
Vowels are generally identified by the F_1 and the F_2 formants, with the F_3 playing a smaller role, while the F_4 and the F_5 are identified as part of the voice timbre.
Classically trained vocalists are often challenged with having to stand out from orchestras, which cover a wide portion of the frequency spectrum. These singers have learned to place more emphasis in the 2-4 KHz frequency band that is not very well covered by the orchestra. This is called the Singers Formant. This is accomplished by bringing the larynx down and narrowing the vocal tract. This shape helps the voice get more energy in the 2-4 KHz frequency band.
