That individual vowels are very difficult to identify. Although we can understand whole sentences (using contextual There isĪt low frequencies so the sound is thin and squeaky. The speech does, however, sound 'like Donald Duck'. The pitch is determined by the frequencies of the If you do the experiment with someone who has some experience with singing or music, (and if s/he doesn't laugh too much on hearing helium voice) What does this sound like? Obviously the helium makes a big difference to the sound of the voice. In your vocal folds still vibrates at the same* frequency, however, so the harmonics occur at the Higher frequencies, as do the formants they produce: the second formant has now been shifted right off scale in this
Helium voice change full#
trying to pronounce theĪs before, but with a throat full of helium). With helium, but keeping the tract configuration the same (i.e. Harmonics of the vibration of the vocal folds. The solid line is the spectral envelope the vertical The first diagram shows a schematic picture of the spectrum (power vs frequency) for the sound of the voice made with a particular So I've put the recordings of my experiment below. Okay, having read those warnings, you might not want to try. In a gas cylinder, He is under high pressure. After one inhalation of He, breathe air normally for To make it clear,Ĭan sing with and without a lung containing a substantial fraction of He and listen. In speech, you may have the illusion that the pitch hasīecause one doesn't think much about pitch when listening to speech. Is determined by the tension, mass and geometry of vocal folds, and some other effects. As you would expect from the model above, it does not change the pitch, which Inhaling heliumįrequencies of the resonances, and therefore of the formants they produce (See What is a formant?). You can investigate the model described above by changing the speed of sound. For this 'neutral' vowel, the first five resonances ofĪuthor's vocal tract are indeed at values of about 500, 1500, 2500, 35 In fact a closed tube of this length is a functional Gives resonances around 500 Hz and above. The phone even though the fundamental of that signal is not present. Of harmonics as much as or more than by the fundamental. (The telephone carriesĤ kHz but speech is reasonably intelligible.) The pitch is determined by the spacing Nearly all information in speech is in the range 200 Hz - 8 kHz. Maps of (R1,R2) for various accents of English are given on Sounds of World English. R2 (and also R1, but to a lesser extent). Moving your tongue forwards and backwards R2 is affected by the jaw position too, but it is primarily affected by the position The lowest resonance is determined to a considerable extent by the end effect of your forĪ low pitched man's voice (diagram at left), than it is for a child's voice. Note that the detail in the spectrum is easier to see if F0 is low, e.g. The peaks in the envelope of the sound spectrum. In the case sketched at left below, the resonances R1 and R2 can be determined Radiation properties of the mouth, face and external field, produce a sound output (C).īecause the source is harmonic, we can say that the gain of the tract (B) is sampled at The input signal and the vocal tract, together with the It is variable because, by changing the position of your tongue, jaw etc you can change that frequency response. The tract behaves like a variable filter (B) in that its response is different for different frequencies. 'What is a sound spectrum?' for an introduction.) This source signal
(A periodic signal is cyclic: its motion is reproduced after a time interval called itsĬonsequence is that its spectrum is made up of harmonics. Vibration of the vocal folds in the larynx produces a varying air flow which may be treated as a periodic source (A). The source-filter model of the vocal tract See also the more complete Introduction to the physics of speech. Uses this to explain some of the most noticeable features of helium speech, which it illustrates with sound files. Speech and helium speech (and very brief notes about the physics of the voice)ĭoes helium change the pitch of the voice? This short document gives a very brief description of the source-filter model of voiced
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