A formant is a peak in the frequency
spectrum of a sound caused by acoustic
the word refers to sounds produced by the vocal
tract. In acoustics, it refers to resonance in sound
sources, notably musical
instruments, as well as that of sound chambers. However,
it is equally valid to talk about the formant frequencies
of the air in a room, as exploited, for example, by Alvin
Lucier in his piece I
Am Sitting in a Room.
of American English vowels [i,
u, ɑ] showing the formants f1
Formants and phonetics
Formants are the distinguishing or meaningful frequency
components of human speech
and of singing.
By definition, the information that humans require to
distinguish between vowels
can be represented purely quantitatively by the frequency
content of the vowel sounds. Formants are the characteristic
that identify vowels to the listener. Most of these formants
are produced by tube and chamber resonance,
but a few whistle tones derive from periodic collapse
effect low-pressure zones. The formant with the lowest
frequency is called f1, the second f2,
and the third f3. Most often the two
first formants, f1 and f2,
are enough to disambiguate the vowel. These two formants
determine the quality of vowels in terms of the open/close
and front/back dimensions (which have traditionally, though
not entirely accurately, been associated with the position
of the tongue). Thus the first formant f1
has a higher frequency for an open vowel (such as [a])
and a lower frequency for a close vowel (such as [i] or
[u]); and the second formant f2 has
a higher frequency for a front vowel (such as [i]) and
a lower frequency for a back vowel (such as [u]).
Vowels will almost always have four or more distinguishable
formants; sometimes there are more than six. However,
the first two formants are most important in determining
vowel quality, and this is often displayed in terms of
a plot of the first formant against the second formant,
though this is not sufficient to capture some aspects
of vowel quality, such as rounding.
Nasals usually have an additional formant around 2500
Hz. The liquid [l]
usually has an extra formant at 1500 Hz, while the English
"r" sound ([ɹ])
is distinguished by virtue of a very low third formant
(well below 2000 Hz).
(and, to some degree, fricatives)
modify the placement of formants in the surrounding vowels.
sounds (such as 'b' and 'p' as in "ball" or "sap") cause
a lowering of the formants; velar
sounds ('k' and 'g' in English) almost always show f2
and f3 coming together in a 'velar pinch'
before the velar and separating from the same 'pinch'
as the velar is released; alveolar
sounds (English 't' and 'd') cause less systematic changes
in neighboring vowel formants, depending partially on
exactly which vowel is present. The time-course of these
changes in vowel formant frequencies are referred to as
If the fundamental frequency of the underlying vibration
is higher than the formant frequency of the system, then
the character of the sound imparted by the formant frequencies
will be mostly lost. This is most apparent in the example
singers, who sing high enough that their vowels become
very hard to distinguish.
Control of formants is an essential component of the
vocal technique known as overtone
singing, in which the performer sings a low fundamental
tone, and creates sharp resonances to select upper harmonics,
giving the impression of several tones being sung at once.
are used to visualise formants.
Vowel formant centers
||Main formant region
||400–600 and 2200–2600 Hz
||200–400 and 3000–3500 Hz
Studies of the frequency spectrum of trained singers,
especially male singers, indicate a clear formant around
3000 Hz (between 2800 and 3400) that is absent in speech
or in the spectra of untrained singers. It is increase
in energy at 3000Hz which allows singers to be heard and
understood over an orchestra,
which peak at much lower frequencies of around 500 Hz.
This formant is actively developed through vocal
training, for instance through so-called "voce
di strega" or witch's voice
exercises and is caused by a part of the vocal tract acting
as a resonator.
Titze, I.R. (1994). Principles of Voice Production,
Prentice Hall, ISBN
Ladefoged, Peter (2006) A Course in Phonetics (Fifth
Edition), Boston, MA: Thomson Wadsworth, p. 188.
Ladefoged, Peter (2001) Vowels and Consonants: An
Introduction to the Sounds of Language, Maldern,
MA: Blackwell, p. 40. ISBN
Deterding, David (1997) 'The Formants of Monophthong
Vowels in Standard Southern British English Pronunciation',
Journal of the International Phonetic Association,
27, pp. 47-55.
Hayward, Katrina (2000) Experimental Phonetics,
Harlow, UK: Pearson, p. 149. ISBN
Anthony (2007). Baritone Voice. Boston: Branden
Books, 84. ISBN
Ring, or The Singer's Formant". The National
Center for Voice and Speech. Retrieved on 2008-04-07.
Johan (1987). The science of the singing voice.
DeKalb, Ill: Northern Illinois University Press. ISBN