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Vibrato is a type of low-frequency frequency modulation. Learn about vibrato produced by the singing voice and musical instruments, experiment with the vibrato effect using an interactive LabVIEW VI, and learn how to model the vibrato effect mathematically.
This module refers to LabVIEW, a software development environment that features a graphical programming language. Please see the LabVIEW QuickStart Guide module for tutorials and documentation that will help you:
•Apply LabVIEW to Audio Signal Processing
•Get started with LabVIEW
•Obtain a fully-functional evaluation edition of LabVIEW

Overview

Vibrato is a type of low-frequency frequency modulation. After learning about vibrato produced by the singing voice and musical instruments, you will experiment with the vibrato effect using an interactive LabVIEW VI and learn how to model the vibrato effect mathematically.

Physical vibrato: singing voice and instruments

Vocalists and instrumentalists will introduce vibrato -- a low-frequency variation in pitch -- into long sustained notes primarily to add musical interest. Listeners are drawn to sounds with dynamic (changing) spectral characteristics, and vibrato makes a sustained note sound much more interesting than a constant frequency. Moreover, sustaining a long note at a constant frequency with sufficient accuracy to avoid drifting "out of tune" is challenging for vocalists and wind-based instruments. Vibrato is produced in a variety of ways, depending on the instrument. Trombonists wiggle the slide slightly to change the overall tube length that sets pitch. A violinist will rock his or her left hand that presses the string to slightly alter the effective string length.

Vibrato demonstration

Download and run the LabVIEW VI vibrato.vi to demonstrate the vibrato effect applied to a sinusoidal oscillator. This VI requires the TripleDisplay front-panel indicator. Vibrato normally requires two controls: rate determines how quickly the frequency should fluctuate, and depth establishes the amount of frequency fluctuation. The third control adjusts the pitch of the sinusoidal oscillator.

Modeling the vibrato effect

Vibrato is a type of low-frequency frequency modulation . In this section the mathematical equations necessary to model the vibrato effect will be developed.In addition, two important effects associated with the singing voice will be discussed to produce a more realistic model.

Naive approach

The screencast video develops the mathematical equation needed to model the vibrato effect in perhaps an intuitively-obvious (but unfortunately incorrect) way. After watching the video, try the interactive front panel VI below that is part of the demonstration, then respond to the exercise questions to ensure that you understand the main concepts.

[video] Perhaps "intuitively-obvious" (but incorrect) way to model vibrato

Download and run the LabVIEW VI vibrato_naive.vi .

What is the main auditory effect produced by the intuitively-obvious approach to modeling vibrato?

The amount of frequency fluctuation (deviation) increases with time rather than remaining constant.

When modifying the basic sinusoidal oscillator equation, which part -- frequency or phase - requires the most attention?

Phase; the entire argument to the sine function must be considered as a time-varying phase function ϕ ( t )

How should the phase function ϕ ( t ) be designed to achieve vibrato?

A ramp function with a superimposed sinusoidal variation.

Correct approach

The screencast video develops the mathematical equation needed to model the vibrato effect for a constant low-frequency variation.

Refer again to the LabVIEW VI vibrato.vi you downloaded earlier.

[video] Correct way to model vibratro

Improved realism for singing voice

Several effects become immediately apparent when listening to an opera singer:

  • Vibrato rate begins slowly then increases to a faster rate; for example, listen to this short clip: sing.wav
  • Vibrato depth increases as the note progresses (listen to the clip again: sing.wav )
  • Loudness (intensity) is initially low then gradually increases (listen to the same clip one more time: sing.wav )
  • The "brightness" (amount of overtones or harmonics) is proportional to intensity (please listen to the same clip one last time: sing.wav )

These effects are also evident when listening to expressive instrumentalists from the strings, brass, and woodwind sections of the orchestra. The mathematical model for vibrato can therefore be improved by (1) making the vibrato depth track (or be proportional to) the intensity envelope of the sound, and by (2) making the vibrato rate track the intensity envelope. Modeling the "brightness" effect would require adding overtones or harmonics to the sound.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
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Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
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Google
da
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Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
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I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
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what is the stm
Brian Reply
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Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
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LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
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Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
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Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
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Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
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Adin Reply
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Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
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Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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Source:  OpenStax, Musical signal processing with labview -- tremolo and vibrato effects (low-frequency modulation). OpenStax CNX. Nov 07, 2007 Download for free at http://cnx.org/content/col10482/1.1
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