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Background information on the concepts used in MATLAB EQ project.

Introduction to equalizers

This section will cover the basic principles that we used in the creation of our graphical equalizer: equalizer principles, analog to digital conversion, Nyquist-Shannon sampling Theory, and the fast Fourier transform.

Equalizers

In audio processing, equalization is the process of changing the spectrum of a sound. Equalizers employ low-pass, band-pass, and high-pass filters to modify different portions of a sound’s spectrum. By changing the gains on these filters an operator is able to modify the sound. An easy example to understand would be a‘Bass Booster,’where the user adds gain to the low frequencies and thereby increases the‘bass’of a song. Generally, equalizers have ten different bands that a person is able to manipulate, but high end models can have up to thirty-one.

Analog to digital conversion

Sampling is the process of converting a continuous real time signal into a discrete time signal. The basics of sampling form the basis for much of today’s music recording industry. Sophisticated digital to analog converters (DAC) can be found in music studios across the world.

A DAC works by converting voltages into a digital number representing the corresponding voltage. The digital representations of these signals can then be manipulated by a computer, introducing various effects and gains. After processing, the signal can be converted back into an analog signal using a digital to analog converter.

A visual example of digital sampling of an analog signal.

Nyquist-shannon sampling theory and aliasing

The Nyquist-Shannon theory states that exact reconstruction of a continuous time signal from its samples is possible if the signal is bandlimited and the sampling frequency is at least twice that bamdwodth.

For example, the human ear can hear sounds from 20-20,000Hz. This means that if we want to recreate an audio signal with the complete range of recorded frequencies we must sample the signal at a minimum of 40,000Hz. Typical music is coded and sampled at 44,100Hz which obeys the Shannon-Nyquist theorem. The reason for the extra bandwidth is due to imperfect low-pass filter effects, which is outside the scope of this module.

A visual example of an appropriately band limited signal.

Aliasing occurs when the Nyquist-Shannon Theorem is not obeyed, i.e. when the sampling rate is not at least two times the band limit’s frequency. Aliasing is the overlap of spectrums at the band edges and results in an incorrectly reproduced signal. These overlaps corrupt the signal by adding the two spectrums from the overlapping bands.

A visual example of a aliasing in a signal.

Fast fourier transform

To be able to process bandwidth gains, one must move the samples of the continuous time signal into the frequency regime. This is accomplished quickly and efficiently using the Fast Fourier Transform (FFT). The equation for this is as follows:

The Fast Fourier Transform.

This moves the signal into the frequency regime with N points. There is a problem in that you need a very long FFT to accomplish a perfect spectrum. Long FFTs are computationally expensive and are difficult to accomplish in real time, and a compromise between speed an resolution must be made.

Inverse fast fourier transform

Once the signal has been manipulated in the frequency regime, you have to convert those values back into a digital representation of the signal. To do this you use the Inverse Fast Fourier Transform:

The Inverse Fast Fourier Transform.

Since we have modified the spectrum, this new digital signal may have imaginary parts in it. Digital to analog converters do not interpret imaginary numbers so we must take the real part of the modified signal to be able to reproduce it.

Questions & Answers

yeah. after a research question is attained, you make a tentative statement that will either confirm your theory or not
Wayne Reply
is hypothesis first drawn before theory
Nwankwo Reply
a tentative statement that precedes the theory ascertained, so yeah
Wayne
How does cognition and memory links with perception?
Catalina Reply
let's talk Sigmund Freud psychosexual theory and psychoanalytic theory.
Catalina
sure but I dont kn now him actually so explain him
Ruth
can I ask u all a question?
Ruth Reply
no
Ximax
come on it's about profiling
Ruth
yeah
Sz
how do u know that someone is in trouble but pretend that they aren't
Ruth
you need to looks for clues. otherwise there is no ready-made answer to your question.
Paul
what if they were acting weird and want to talk but can't
Ruth
also clues like what
Ruth
how to ready human mind
Sujeet Reply
how to read human behaviour
Sujeet
Describe frontal lobe syndrome
Bridget Reply
Frontal lobe syndrome is an impairment of the frontal lobe that occurs due to disease or head trauma. 
Zafar
what does the bell curve represent in intelligence testing?
Sounny Reply
average
Angela
I'M A VERY CURIOUS PERSON WHO LOVES TO LEARN ABOUT DIFFERENT TYPES
Sheri Reply
I AM A PERSON WHO IS NOT CHOOSING TO LET MY MENTAL HEALTH AFFECT ME AND I AM AN
Sheri
different types means.?😂😂
rilek
Indeed....different types means what exactly and how does these different types transpire into our lives? there are many different ways of allowing ourselves to accommodate and continiously play out the fact we have mental illnesses!!!
Elizabeth
social learning theory
CONFERENCE Reply
how we know the people are telling lie
Vasu
human brain
SERAJ
if you want to learn how to detect the lie you have to observe their behaviour...
Aayan
that's common things..
MOHD
anything specially, tht we can say either person is telling yes or no..?
MOHD
Yes
rochell
I believe there are many factors that play into being a human lie detector.
Tasha
all of which is governed by the human brain.
Tasha
There's no accurate method of telling someone is lying unless we know the truth ourselves. Some people, especially people with manipulative tendencies, will make a lie as believable as possible. Behaviors could tell the person is hiding something or may be feeling uncomfortable while being observed.
agii
Ex. Talking too fast while explaining a story might indicate that the person is indeed hiding something. Other than that, people, usually with histrionic personality disorder, also tend to exaggerate stories.
agii
DORFRLYN It's not easier to feel lied at first moment of talking to someone you know or you don't know. The person will be guilty of what they tell in the first sentence.They first find a way to hide the the truth. By so doing, the movement, and the head knock, this symbloyz the shift of origin
dorfrlyn
for one to tell lies, should first read the mind of the listener.
dorfrlyn
I agree with you Agil.Usually a person talks too fast,is hiding something true. But also talking too slow will mean creation of new story rather than the truth.
dorfrlyn
some people have the habit of speaking too fast, so in that case how can we identify whether the person is lying or not?
Labdhee
pay attention on facial expressions
El
When people talk too fast to the point that it's incomprehensible, it could mean that that person is trying to have you move one from one topic to another to prevent you from asking questions.
agii
observe micro expressions
Zafar
thanks to all for giving ans😃
Vasu
I want to learn more about psychodynamic personality theory
MsPam
MsPam Ware send me you email ... I just did a paper on Psychodynamic ...I can email it to you .. you may find it useful
Shanelle
Just wrapped a blackboard discussion on that! Theory is a great class. :)
Rachael
what if somebody answers questions quickly because they have social anxiety
Ashley
detecting lies is easier than many think. the dynamics of listening, body language, facial expression, story line, deductive reasoning and most of all analytical skills all play a role in determining if someone is lying. micro expressions can be very hard to discern requiring close analysis!
Kyth
Any recommendations for apps related to positive psychology?
Andrew Reply
intresting I mean
Asfand
Sometimes if you type "positive psychology " in your play store, you'll get some good ones
Tahmetrea
I use Awakenings by Iyanla Vanzant... She have a positive outlook on life. She's awesome!
Tahmetrea
Thank you, I will check that out.
Andrew
CBT types?
Rachael
psychology FACTS
katy
ITS SUPER EASY TO USE ... and divides the kind of positive psychology your looking for into groups! check it out.
katy
mental association books?
Maya
CBT works, and I am also looking for a psych book to read... I like psychology facts
Andrew
anyone know about any bipolar advocate groups or support type groups where a person can talk n vent while remaining anonymous?
tonya
HI I'M SHERI AND IN ANSWER TO THE QUESTION ABOUT THE BIPOLAR SUPPORT GROUPS I LIVE IN SACRAMENTO CALIFORNIA AND I DO KNOW THAT THERE ARE MANY DIFFERENT GROUPS 1) WELLNESS RECOVERY PROGRAMS AND I KNOW OF 2 LOCATIONS ONE ON MARCONI IN NORTH SACRAMENTO AND ON BOWLING OFF FLORIN IN SOUTH SACRAMENTO
Sheri
what's the most common cause of suicide in adolescents
Aisha Reply
depression
Irfan
yes. it's depression.
Paul
Especially when adolescents go through identity issues. Not knowing if this boy wants to be a girl or vice or versa. Social awkwardness, depression and cruelty of other adolescents in my opinion, brings a lot of suicidal tendencies into the minds of them.
Tahmetrea
reasons that lead to depression caused by many reasons like rape, abusive parents or guardians, bullying and more causes for a person to suicide
Diana
not accepting the fact or situation or the reality. the adolescents can't face rejections, as soon as they are rejected , they commit suicide.
Labdhee
social pressures have a huge impact on this. I find that young people are more likely to take their own life because they feel they are not able to fit in to a particular group of society and feel they are criticised by others. environment and nature/nurture. identity is a huge factor.
Jody
I think a major problem is when someone feels they can't handle the situation or think it's out of the control even though there are a lot of ways to solve it, one of them being at least trying to tell someone, visit a psychologist. They might stop feeling alone/misunderstood by everyone else.
Thuy
well, I've a problem. I feel very conscious when I'm in a crowd. when I'm partying with friends, I feels like everyone is looking at me. when I look at them, each one of them have their eyes on me. I don't know how I should deal with this? can someone help me with that ?
puneet
Hey Puneet! I think it's the matter of time and getting comfortable in that kind of situation after you try to get out of your comfort zone and slowly get used to it. I used to have that problem too but then I acted to not give a 💩 and tried my best to pretend I didn't care at all. And it worked!
Thuy
*Fake it till you make it* in this case worked for me the best. Maybe you could try to start talking to one of the more open/friendly people in that group so you don't get that self-conscious. I'm sure they don't think they will judge you at all! Just do it!
Thuy
Bullying that leads to anxiety, shame and depression, sadly.
Rachael
Where do I go to find research or tips for integrating sex and mental heath?
Felicia Reply
integrating a sexual routine and a mental illness that has kept o e from intimacy for a prolonged time? can u be a Lil more specific
lindsay
I have experience with both
lindsay
y only these two.?
MOHD
yes
Abu
y only these two sex and mental
MOHD
knowledge some practice practical
Abu
so ur mentally in balanced with sex..cause you find a good satisfy partner.....
MOHD
u can explain
Abu
u can't find good sex partner....
MOHD
no
Abu
I m not understand your consepet
Abu
depends on your Lonely no family no friends
MOHD
ok
Abu
chill,u time to Understand these concepts..
MOHD
ok
Abu
u can explain in urdu
Abu
hi
Wendy
hi
Abu
please can you help me identify and explain atleast seven(7) reflexes of the new born.
Wendy
yes of course
Abu
kk, then i need your help please.
Wendy
what's going on?
Mohammad
@lindsay I want to show how sexuality and mental health correlate. How one affects the other.
Felicia
I can help on these subjects
Abiral
@Abiral what information do you have?
Felicia
Hello
Irfan
Spending quiet time alone, with nature can improve mental health. Offer your opinions?
tsav Reply
mmmm but me i cn not spend time alone
Gift
Different strokes for different folks 🤷🏽‍♂️
tsav
what do u mean
Gift
Some people prefer a quiet life to a busy, bright city life. Some lead very stressful lives. Those people often don't pay attention to how they feel apart from the obvious fact that they're tired and stressed
tsav
nature can be clarifying and soothing because it can be a mixture of just natural beauty and why else are nature sounds an option for white noise
Twisted
You're absolutely right
tsav
what is with human being brain that we don't know?
imran Reply
I guess there are lots of things we don't know, but perhaps your referring to that thing called Consciousness
GoldenWizard
Anything that happens, question it!
tsav
in addition we may ask the doctor's
Gift
the science of many feelings and emotions can be hard to describe. our brains light up at some things but we can't always understand why
Twisted
But yet we must persist
tsav
Using relevant examples discuss challenges encounter by the beginning teachers during the learning and teaching process
LEILA Reply
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Source:  OpenStax, Elec 301 projects fall 2007. OpenStax CNX. Dec 22, 2007 Download for free at http://cnx.org/content/col10503/1.1
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