<< Chapter < Page Chapter >> Page >
Discovering quirks in MATLAB, finding a simple noise filter, and getting great sound!

Creating the distortion

As we discovered in Problems with Distortion , when we work with the modified power series, we do not get the expected result. In fact, we onlyget a lower quality version of our original sound file! However, taking a look at the minimum and maximum of our soundvector, we soon discover the problem: all values of our signal are between 1 and -1! When we take these numbers to the tenpower, or even the five power, all we do is make our sound values smaller. Therefore, a quick fix would be to take thesenumbers to the one-tenth power or the one-fifth power, in effect dividing each power by ten. Upon checking out our signal, we get thewonderful distortion that we needed! As we play around with different coefficients and powers (all less than one), our owndiscerning ears determine which coefficients and powers are best for the distortion we want. However, in all of thisplaying around, a particular evil has crept in among our distortion: noise!

Dealing with the noise

Several different methods can be used to take out the noise from our signal. In fact, an entire project was dedicated to noise-elimination in 2002. However, since this project focuses mainly on a MATLABapproach rather than a C approach, we'll leave implimenting that noise filter to a more adventurous group.

The simplest way to get rid of the noise would be to impliment a band pass filter in MATLAB, allowing only for the frequencyrange of the guitar (about 100Hz to about 4000Hz, perhaps higher depending on the high notes you play). This filterwill get rid of most of the noise, except for the noise that lies within those frequencies.

Another easy way to get rid of the noise involves the FFT. After taking the FFT of the signal, you can decrease noise bythrowing out the frequencies below a certain threshold.

Questions & Answers

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Ece 301 projects fall 2003. OpenStax CNX. Jan 22, 2004 Download for free at http://cnx.org/content/col10223/1.5
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Ece 301 projects fall 2003' conversation and receive update notifications?

Ask