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Algorithm For Identifying the Notes

Step 1: Convert the music segment into frequency domain

Because our recorded music files are chopped into fixed finite length segments, all we have to do is apply DFT to the sample. Considering speed of computation, we decided to use the method of computing with the DFT matrix .

We know that DFT samples are defined by



Thus can be expressed in matrix form as


By using the matrix method to compute the DFT, we can calculate the DFT of many pieces of same length and same sample rate music segments at the same time using the same matrix. This will increase the overall speed of our program and enable tune identification for lengthy music that consists of thousands of segments to be analyzed.

Step 2: Find the peaks in the frequency domain representation of the segmented music. Identify the peaks whose frequencies are near integer multiples of each other and group them into the same category.

We know that notes played by instruments have harmonics which the frequencies are integer multiples of the base frequency. Often the note that’s being played is the base frequency or the first odd harmonic of the base frequency. Thus, peaks which frequencies are near integer multiples of each other indicate that they are mostly likely to be the harmonics of a base frequency and the note that’s being played lies within it.

To identify the harmonics we used findpeaks function in Matlab and grouped them in a matrix which the i-jth entry is the frequency of the jth peak over the frequency of the ith peak. We then look for near integer entries in the matrix to determine peaks whose frequencies have integer multiples relationship and categorize them together. The peak with the lowest frequency in each category is the base band while the other peaks in the same category are its harmonics.

Step3: Use the power of peaks to determine the most significant categories.

Because there may be noise and other random vibrations when an instrument is played, there are categories which do not contain the note that’s played by the instrument. On the other hand, when multiple notes are played at the same time (aka a chord), there may be multiple categories which contain notes that are played. To correctly analyze the notes that are being played, we pick out the category which has the most power and categories whose powers are larger than one-tenth of that. The way we calculated the power of each category is by summing up the power(frequency*peak^2) of all the harmonics in that category. After this process, ambient noise and vibrations should be excluded and the remaining categories should contain the notes that are being played.

Step 4: Determine the notes that lie in each category.

Mostly, the base frequency of each category is the note that’s played by the instrument. However, we’ve learned that the note played by some instruments is either the base frequency or the first odd harmonic of the base frequency. To determine which note is being played, we compared the sum of the power of odd harmonics versus the sum of the power of the even harmonics in each category. When the power of even harmonics is larger than a certain times of the power of the odd harmonics, we say that the note is the base frequency; otherwise, we say that the note is the first odd harmonic of the base frequency.

Questions & Answers

what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
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Source:  OpenStax, Tune identification. OpenStax CNX. Dec 20, 2011 Download for free at http://cnx.org/content/col11399/1.1
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