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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

explain and give four Example hyperbolic function
Lukman Reply
The denominator of a certain fraction is 9 more than the numerator. If 6 is added to both terms of the fraction, the value of the fraction becomes 2/3. Find the original fraction. 2. The sum of the least and greatest of 3 consecutive integers is 60. What are the valu
SABAL Reply
1. x + 6 2 -------------- = _ x + 9 + 6 3 x + 6 3 ----------- x -- (cross multiply) x + 15 2 3(x + 6) = 2(x + 15) 3x + 18 = 2x + 30 (-2x from both) x + 18 = 30 (-18 from both) x = 12 Test: 12 + 6 18 2 -------------- = --- = --- 12 + 9 + 6 27 3
Pawel
2. (x) + (x + 2) = 60 2x + 2 = 60 2x = 58 x = 29 29, 30, & 31
Pawel
ok
Ifeanyi
on number 2 question How did you got 2x +2
Ifeanyi
combine like terms. x + x + 2 is same as 2x + 2
Pawel
Mark and Don are planning to sell each of their marble collections at a garage sale. If Don has 1 more than 3 times the number of marbles Mark has, how many does each boy have to sell if the total number of marbles is 113?
mariel Reply
Mark = x,. Don = 3x + 1 x + 3x + 1 = 113 4x = 112, x = 28 Mark = 28, Don = 85, 28 + 85 = 113
Pawel
how do I set up the problem?
Harshika Reply
what is a solution set?
Harshika
find the subring of gaussian integers?
Rofiqul
hello, I am happy to help!
Shirley Reply
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Abdullahi
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Mark
I need quadratic equation link to Alpa Beta
Abdullahi Reply
find the value of 2x=32
Felix Reply
divide by 2 on each side of the equal sign to solve for x
corri
X=16
Michael
Want to review on complex number 1.What are complex number 2.How to solve complex number problems.
Beyan
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Mark
use the y -intercept and slope to sketch the graph of the equation y=6x
Only Reply
how do we prove the quadratic formular
Seidu Reply
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Darius
hello, if you have a question about Algebra 2. I may be able to help. I am an Algebra 2 Teacher
Shirley Reply
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Seidu
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Opoku
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Tric Reply
4
Trista
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
can you teacch how to solve that🙏
Mark
Solve for the first variable in one of the equations, then substitute the result into the other equation. Point For: (6111,4111,−411)(6111,4111,-411) Equation Form: x=6111,y=4111,z=−411x=6111,y=4111,z=-411
Brenna
(61/11,41/11,−4/11)
Brenna
x=61/11 y=41/11 z=−4/11 x=61/11 y=41/11 z=-4/11
Brenna
Need help solving this problem (2/7)^-2
Simone Reply
x+2y-z=7
Sidiki
what is the coefficient of -4×
Mehri Reply
-1
Shedrak
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
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Source:  OpenStax, Musical signal processing with labview -- additive synthesis. OpenStax CNX. Nov 07, 2007 Download for free at http://cnx.org/content/col10479/1.1
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