Information AboutFormant |
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A formant is a peak in an acoustic Frequency Spectrum which results from the Resonant frequencies of any acoustical system. It is most commonly invoked in Phonetics or Acoustics involving the resonant frequencies of Vocal Tract s or Musical Instrument s. 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 ''. 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 representated purely quantitatively by the frequency content of the vowel sounds. Formants are the characteristic Partial s 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 of Venturi Effect low-pressure zones. The formant with the lowest frequency is called ''f''1, the second ''f''2, and the third ''f''3. Most often the two first formants, ''f''1 and ''f''2, are enough to disambiguate the vowel. These two formants are primarily determined by the position of the tongue. f1 has a higher frequency when the tongue is lowered, and f2 has a higher frequency when the tongue is forward. Generally, formants move about in a range of approximately 1000 Hz for a male adult, with 1000 Hz per formant. Vowels will almost always have four or more distinguishable formants; sometimes there are more than six. Not all sounds used in human language are composed of formants. Formants are restricted to Sonorant s, a subset of Pulmonic sounds including Vowels , Approximants , and Nasals . Nasals usually have a formant around 2500 Hz in addition to two lower formants (and, where applicable, voicing). The liquid usually has a formant at 1500 Hz, while the English "r" sound ( IPA ) is distinguished by virtue of the third formant, which dips below 2000 Hz. Plosives (and, to some degree, fricatives) modify the placement of formants on the surrounding vowels. The distinguishing formant drop for is characteristic of Retroflexes , for instance. Bilabial sounds (such as 'b' and 'p' as in "ball" or "sap") sometimes feature a dip in the first two formants. Velar sounds ('k' and 'g' in English) almost always show F2 and F3 coming together before the velar and separating from a point once the velar sound is completed. Alveolar and Dental sounds (English 't' and 'd') show little change from the ordinary formant positions. Note that fricatives always lack formant structure and are distinguished by the frequency range with the most noise, as well as overall strength of frication. 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 of Soprano Opera 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. Spectrogram s are used to visualise formants. SINGER'S FORMANT Studies of the frequency spectrum of trained Singers , especially male singers, indicate a clear formant around 3000 Hz that is absent in speech or in the spectra of untrained singers. It is this formant which allows singers to be heard and understood over an Orchestra . This formant is actively developed through Vocal Training , for instance through so-called '' Voce Di Strega '' exercises. SEE ALSO EXTERNAL LINKS |
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