Questions tagged [harmonics]

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Laplace transform for damped waves

In Zeidler's book on QFT, page 94 there is a definition for a Laplace transform that reads \begin{equation} (\mathcal{L} f)(\mathcal{E}) = \int_0^\infty e^{i\mathcal{E}t/\hbar}f(t) dt, \end{equation} ...
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7answers
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Why do higher harmonics have a lower amplitude than the fundamental frequency?

When we pluck a string, it vibrates in all possible modes of vibrations. The lowest frequency possible is the fundamental frequency and it is the most significant part of sound. But why do the ...
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1answer
34 views

Question regarding open and closed air columns

I'm studying high school physics and I've encountered this question: An air column that is open at both ends has a distance of 24.0 cm from one resonant length to another. What is the wavelength ...
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1answer
146 views

Why are there no even harmonics in a closed pipe?

I have seen a diagram on sites such as hyperphysics.com that show that there is a missing bit every time so that it makes every harmonic odd. I was hoping I could get a more intuitive explanation. We ...
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3answers
100 views

Relation between frequencies of different harmonies

I know the relation between frequencies of different harmonies is $$ f_n = n\times f_1 $$ but I'm heving trouble to develope the equation which proves this equality. can anyone please give me a lead ...
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1answer
14 views

How do cavity resonators differ from tubes of uniform width?

I read that wine bottle produces sound when u blow sideways onto its rim because some frequencies of the white noise produced in your mouth gets amplified when they match the natural frequency of the ...
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1answer
44 views

Finding the conditions for a resonant (unique single mode) state in the wave equation

If we have a string of length $L$ in constant tension $T$ and we oscillate one of the extremes at the rate $\sin{\frac{\pi nc t}{L}}$, we observe in a lab that single harmonics are produced. I want to ...
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1answer
85 views

What is the relation between the fundamental frequency and a harmonic?

I am currently busy with a physics report about determining the speed of sound in air. In order to do this, I was told to use a tube that can extend or shorten in order to find the different harmonics ...
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1answer
39 views

What causes this high frequency “noise” in HHG spectra?

Looking at high harmonic spectra, one can often see that peaks corresponding to higher harmonics look more and more noisy and seem to be drowned out by the noise. For example, one such spectrum is ...
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39 views

Are there any resonant frequency spectra that do not possess any harmonics?

I’m hoping that somebody can help clarify the following passage regarding standing waves and the systems that support them: Many systems that support standing waves have resonant frequency spectra ...
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1answer
215 views

Resonant frequencies in organ pipes

I have a series of doubts regarding the principle of organ pipes. For a given length of closed organ pipe there are various modes of vibration for the standing waves.I dont know if this is silly but ...
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16 views

Dependance of number of harmonics from force of collision

I recently found out that if hit something hard, it will produce all harmonics, but if hit with less and less force firstly low harmonics will disappear firstly and only high will stay. Why so?
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1answer
30 views

Why are planet's maximal/minimal angular speed ratio harmonic?

See this Wikipedia page for Harmonices Mundi, a book by Kepler (yes, he was the one to discover the three Kepler's laws). The author writes: He found that the difference between the maximum and ...
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Why coupled oscillators tend to seek integer frequency ratios?

In this document, the author writes (page 225) Coupled oscillators have a tendency to seek frequency ratios which can be expressed as rational numbers with small numerators and denominators. For ...
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0answers
44 views

Is there a way to know the non-zero coefficient of $\cot(\theta)$ expansion in spherical harmonics?

I'm currently trying to find an analytical solution to the Poisson equation for a given distribution using a multipole expansion. During this task, I found the radial expansion and everything else, ...
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2answers
79 views

How many linear combinations of harmonics or normal modes can describe the same periodic function as a Fourier series?

Please note that I am not asking how many terms in a linear combination can describe a specific periodic function but if given that there exist a set or linear combination of normal modes that ...
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42 views

At what rate is tension released from a plucked string (eg. guitar string)?

Tension in a plucked string (such as a guitar) dictates many of the important changes that occur in the sound of the string over time. eg. It causes a pitch bend, a change in inharmonicity, and ...
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2answers
184 views

Why can an inner product of an eigenvector also be used as an eigenvector?

In quote box below, there is an inner product of an angular momentum eigenvector. Why can you use this inner product as a new eigenvector for the next part of the work? And why do they "of course" ...
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0answers
37 views

Why a musical instrument's string oscillates with many frequencies? [duplicate]

I am trying to understand why when we play a note on a stringed instrument, not only it oscillates with it's fundamental frequency but also the multiples of that. For instance if you play a D on the ...
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1answer
94 views

Harmonics in a tube closed at one end

I have been learning about sound and how a tube closed at one end only seems to have odd harmonics. However, I have found that although clarinet follows this and plays only odd harmonics, saxophone ...
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1answer
425 views

De Broglie explanation of Bohr's second postulate. discrepancy of 2 times?

I am reading how de Broglie justified the 2nd postulate of Niels Bohr (i.e. angular momentum of an electron to be integral multiple of $\frac{h}{2\pi}$). I get his explanation of electron acting like ...
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2answers
134 views

Why the faster you spin the highest the pitch get in a whirly tube? [duplicate]

I would like to understand why the faster you spin, higher normal modes are excited This is the tube i'm talking about, i think it's used as a kid's toy: https://www.youtube.com/watch?v=eCOZxzO3FvE ...
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0answers
73 views

sounds of polygonal ring chimes of metal

Suppose we have a number of rings, each of them is constructed from some mass of wrought iron or steel: each ring is a polygon, which I would like to suppose is constructed without welding (so they ...
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1answer
80 views

Integer multiples of fundamental time period? [closed]

If we define harmonics to be positive integer multiple of fundamental frequency What will we say to positive integer multiples of fundamental period?
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1answer
164 views

Is the first harmonic the prevalent frequency? [closed]

Why, when we play a string, almost all of the energy we give them is ''used'' in the first harmonic (the fundamental frequency) rather than be distributed between all of them?
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4answers
3k views

If all harmonics are generated by plucking, how does a guitar string produce a pure frequency sound?

A guitar is a plucked instrument and it is played by plucking a string at an off-centre point fixed at two ends. In general, Fourier analysis tells that all harmonics (the resonant frequencies of the ...
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2answers
65 views

Why are there these other “harmonics” (violin-specific terminology) in violins?

I've often read explanations of how standing waves form on the string of a violin and their harmonics but there is another phenomenon I've never seen explained: When you play certain notes, musicians ...
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3answers
124 views

Why, in an open or half-open pipe, must an open end of a standing sound wave have a pressure of zero?

I believe this question was asked in some form before, but I'm not clear on the answer. If a sound wave must equal air pressure when it exits a tube, why is it possible that at many points after the ...
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1answer
130 views

Pulling a string with both ends fixed [duplicate]

Consider a string with both ends fixed. If somewhere in middle of it be pulled and released, how would it oscillate and what is it's equation? My solution assuming the result is a standing wave: The ...
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2answers
190 views

How is it possible that multiple overtones can exist at the same time?

I was wondering how it is possible for overtones to co-exist at the same time. When one pulls a string, it starts to oscillate and forms a standing wave with frequency $$f_0 = f$$ Additionally, ...
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1answer
79 views

How do we hear harmonics and how does it affect audio fidelity?

First and foremost, do we hear a sound wave as a sum of all the individual harmonics, at the fundamental frequency, or do we hear all the associated harmonics above the fundamental frequency and ...
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1answer
62 views

Can we consider oscillation of air column in the wind instruments as phonons subject to Bose- Einstein statistics ?

A flute is a wind instrument, which could be modelled as a resonance cylinder open at both ends. Any cylinder resonates at multiple frequencies. A skilful player produces a standing wave in the flute ...
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2answers
264 views

At what frequency does a string vibrate?

When a string with fixed ends vibrates (e.g. plucking a guitar string) Fourier Theorem says that the vibration can be expressed as a sum of its normal modes, which are sinusoidal vibrations with ...
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2answers
61 views

Which book would you recommend for a dummy wanting to start studying acoustics, out of interest?

I've been very into acoustics lately, specifically the harmonic series. I find it fascinating how the harmonic series works as a sort of guideline to harmony, and how we base tuning systems on trying ...
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1answer
350 views

Where do pure tones occur in nature, besides harmonics?

When you sound a tuning fork, you hear an pure tone/sine wave of usually 440Hz. Yesterday, I tried hitting a table knife made entirely from stainless steel against a grapefruit. When I held it up to ...
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1answer
50 views

Are These Guitar Strings Demonstrating Subharmonics?

This video has a fair few instances where there is an exaggerated wiggling of the guitar strings. I rationalise this by saying its a similar effect to rotoscoping, like where wheels appear to spin ...
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2answers
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Is second harmonic generation a special case of high harmonic generation?

That might be a strange question, but while I was researching for these topics, I never found an explicit statement that would answer that question. (That might be because of the different ...
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4answers
270 views

If a guitar note is determined by the fundamental frequency, what is the relationship between this and octaves?

All the research I've been doing tells me that a guitar note is determined by the fundamental frequency played. But say you play an A on the open A string (110 Hz), and then play a higher octave A by ...
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4answers
3k views

How are overtones produced by plucking a string?

I read the following from wikipedia: When a string is plucked normally, the ear tends to hear the fundamental frequency most prominently, but the overall sound is also colored by the presence ...
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1answer
210 views

Why do two tubes with different lengths produce different frequencies?

I've learned that it has to do with harmonic frequencies and the relationship between length and wavelength in the equation $L = n(\frac{\lambda}2)$, but my question is why? If you were to blow air ...
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3answers
225 views

What does it mean that standing waves oscillate in phase?

What does it mean that all points between two adjacent nodes in a standing wave oscillate in phase? I sort of get what in phase means, it means that the peaks and troughs etc of 2 waves align. But how ...
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2answers
121 views

On Harmonics In Physics

I am an IB physics student. I am very confused about the concept of first, second, third, etc harmonics. My questions are: How does a wave get from first to second harmonic, and from second ...
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2answers
79 views

A pure sine wave vs. the infinite sum of its harmonics

Is a pure sine wave equivalent to the sum of its every harmonic (up to infinity and without the fundamental lets assume)? Moreover, if it is so, is this the reason why all the harmonics are present ...
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3answers
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What is fundamental frequency, how does it make sense?

I’m currently going through harmonics, and I do not at all understand the fundamental frequency. I understand that it is the simplest vibration of a string, but I don't understand how can it have ...
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1answer
117 views

Calculating the decay rates for modes of an ideal circular membrane (ie. drum head) using wave equations?

I am attempting to solve for the theoretical decay rates of the various (m,n) modes of an ideal circular membrane, if that membrane is excited momentarily by an impulse or deformation. I would ...
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1answer
274 views

Fourier Series Analysis [duplicate]

Can anybody explain this paragraph from the chapter " Fourier series and transform " of the book by M l Boas? "If you strike a piano key you do not get a sound wave of just one frequency . ...
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2answers
281 views

Creating sympathetic resonance in a guitar string with an electromagnet

I have an idea for a potential new type of reverb and I wanted to know if it was possible/practical. The idea is to have an electromagnet in the middle of a guitar string(s) which will hopefully ...
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3answers
136 views

Do traveling sound waves have harmonics?

I know that standing waves produce harmonics but what about traveling waves that dont reflect back on itself? Do traveling sound waves have partials that are harmonic(integer multiple of the ...
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1answer
85 views

Must all periodic sound waves have harmonics?

Does there exist a periodic sound wave that has partials which are not integer multiples of the fundamental frequency?
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1answer
890 views

What is the difference between octaves and harmonics? [closed]

my question is about the importance of Octaves vs harmonics? What is the difference between these two concepts?