<< Chapter < Page Chapter >> Page >
In this project you will create an oscillator whose output tracks a specified amplitude and frequency trajectory. With this general-purpose oscillator you can define multiple frequency/amplitude trajectories that can be combined to create complex sounds. In particular, you will design the sound so that its spectrogram makes a recognizable picture!
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

Objective

Additive synthesis builds up complex sounds from simple sounds (sinusoids). Additive synthesis implies more than just doing Fourier series, though: each sinusoidal component is assigned its own frequency and amplitude trajectory (resulting in a partial), so complex, time-varying sounds can be generated by summing these partials together.

In this project you will create an oscillator whose output tracks a specified amplitude and frequency trajectory. With this general-purpose oscillator you can define multiple frequency/amplitude trajectories that can be combined to create complex sounds. In particular, you will design the sound so that its spectrogram makes a recognizable picture!

Prerequisite modules

If you have not done so already, please study the prerequisite modules Additive Synthesis Concepts and Additive Synthesis Techniques . If you are relatively new to LabVIEW, consider taking the course LabVIEW Techniques for Audio Signal Processing which provides the foundation you need to complete this mini-project activity, including working with arrays, creating subVIs, playing an array to the soundcard, and saving an array as a .wav sound file.

Deliverables

  • All LabVIEW code that you develop (block diagrams and front panels)
  • All generated sounds in .wav format
  • Any plots or diagrams requested
  • Summary write-up of your results

Part 1: general-purpose sinusoidal oscillator

Develop a subVI called gposc.vi that accepts a frequency trajectory (in Hz), an amplitude trajectory, and a sampling frequency (in Hz) to produce a sinusoidal output whose amplitude and frequency tracks the two input trajectories, respectively. The two trajectories are arrays that should be of the same length.

Demonstrate that your oscillator works properly by showing the output of your VI (spectrogram and .wav file) for the amplitude and frequency trajectories produced by a LabVIEW MathScript node that contains the following code:

ff=[linspace(200,1600,2.5*fs) ... linspace(1600,800,1.5*fs)]; aa=[linspace(1,0,3*fs) ...linspace(0,0.75,fs)];

where fs is the sampling frequency in Hz, ff is the output frequency trajectory (also in Hz), and aa is the amplitude trajectory (between 0 and 1). Use a sampling frequency of 5 kHz when you make the spectrogram and soundfile.

Plot the trajectories ff and aa and compare to your spectrogram.

Remember, the instantaneous frequency of your general-purpose sinusoidal oscillator is related to the time-varying phase of the sine function. That is, if the sinusoidal signal is defined as y ( t ) = sin ( θ ( t ) ) , then the instantaneous frequency of the sinusoid is ω ( t ) = d θ ( t ) / d t radians per second. Because you are given a frequency trajectory that relates to ω ( t ) , which mathematical operation yields the phase function θ ( t ) ?

Here's a LabVIEW coding tip: You will find the built-in VI "Mathematics | Integ and Diff | Integral x(t)" to be essential for this part of the project.

Part 2: frequency trajectory design

You can make your spectrogram art project sound more musically appealing when you design the frequency trajectories to account for frequency perception ; refer to Perception of Sound for a detailed treatment of this subject. Design your trajectories in "log space" (using logarithmic graph paper) and then convert to actual frequency just before invoking your general-purpose sinusoidal oscillator.

Review Additive Synthesis Techniques to learn how to create your frequency trajectories for this part of the project.

Part 3: amplitude trajectory design

The discussion of Part 2 pertains to the design of your amplitude trajectories, as well. Perception of intensity (loudness) is also logarithmic (refer to Perception of Sound and review the section on intensity perception). In this part you will design your amplitude trajectory in "log space," but now using traditional decibels (dB). An intensity trajectory can be converted to amplitude by "undoing" the equation that relates a value to the same value expressed in decibels: X dB = 20 log 10 ( X ) .

Experiment with your spectrogram display device to learn the intensity-to-color mapping. Specifically, you could produce a sinusoidal signal with increasing intensity values over time, then match up the plotted colors to the known intensity values.

Part 4: spectrogram art

Design a spectrogram picture using multiple frequency/amplitude trajectories. Include your paper-and-pencil drawing of the spectrogram as part of your deliverables. Use your creativity to make an interesting and recognizable picture.

Better designs will go beyond straight lines to include curved lines such as arcs, exponentials, parabolas, sinusoids, polynomials, spline interpolations, and so on.

Include a .wav file of the sound associated with your spectrogram picture.

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..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
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
Jyoti Reply
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.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
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
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
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
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Good
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!





Source:  OpenStax, Musical signal processing with labview (all modules). OpenStax CNX. Jan 05, 2010 Download for free at http://cnx.org/content/col10507/1.3
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Musical signal processing with labview (all modules)' conversation and receive update notifications?

Ask