Vibrato - What is it and how does a singer produce it? (article 5)
This question has arisen in a number of threads on singing sites and deserves some attention. Firstly let’s make a clear distinction between trills and vibrato. (a distinction not understood in a video lesson on the Singing Success site) A trill is a deliberate oscillation between two notes of the scale and will be a semitone or a tone apart – generally used to decorate a cadence approaching a punctuation point in the music and/or the words. There are stylistic rules to obey when executing these ornaments. Vibrato is the quality of a musical note which allows it to carry and ‘caress’ the ear of the listener who will describe it as a warm sound and is produced in different ways depending on the instrument. Vibrato is the resultant of the setting up of a ‘wave interference pattern’ in which the note seems to traverse a very slightly undulating pathway, centred around the basic vibration frequency of the note but well inside the bounds of being ‘in-tune’.
(a) Physically induced vibrato :
(1) in the bowed string family vibrato is produced by slightly altering the finger pressure point by rocking the finger across the true position – this generates a very tight band of frequencies – all in tune to the ear, but as the waves radiate from the sound source they interact and produce a complex amplitude pattern which is translated by the ear into the ‘warm’ sound which is so satisfying to the listener. Of course the total tonal effect of these instruments is also a function of their construction ie some of the vibrato is built into the instrument.
(2) trombone players achieve the same effect by keeping the slide in continuous motion around the ‘true’ position.
(b) Potential for vibrato built into the instrument:
(1) Piano – The upper notes of the piano have paired strings and these are tuned very slightly apart spanning the true frequency and when struck by the hammers generate two waves which interact as they radiate and again produce that sensation of ‘life’ in the note.
(2) Pipe organ – the high flute stops for example have two pipes assigned per note and are tuned slightly apart – the resultant again has warmth and life.
(3) Guitar and Fretted instruments – The construction of the instrument (type of wood – thickness of wood – varnish) determines how many overtones sound when a string is plucked or a chord is strummed and it is again the resultant of the interaction between the fundamental and these overtones which determines the sound of the guitar and its carrying power – the player cannot induce vibrato.
(4) Brass instruments – basic sound is affected by bell shape and size but the life of a note can be completely suppressed if the upper respiratory tract is held rigid preventing air circulation through the nasal and cranial spaces – hence vibrato on these instruments is dependent on physiology.
(c) Vibrato totally dependent on physiology:
(1) This brings us to the human voice – Do not think about vibrato at the level of the vocal folds or cords – they are defining the basic frequency of the note being sung – the singer has to ensure that the air stream can access all the resonating spaces of mouth, nose and head, allowing for production of the full spectrum of possible overtones which by interaction with the fundamental will give that warm lively sound that you all out there are looking for. That is why it is essential to work the voice on warm-ups and exercises which will move the voice around all those spaces to maintain their resonance and keep the voice right off the throat. For such a system see article 4.
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