Why is it called white noise

Just as white light contains all colors, the spectrum of white noise contains all frequencies with constant amplitude.

How does it differ from the pink one? And at this point, why pink? :D

The amplitude spectrum of pink noise presents amplitudes inversely proportional to the frequency, which is why it is also called 1/f noise. Typically, the amplitudes follow a logarithmic trend and, indeed, when reasoning in dB, the characteristic of pink noise is that it loses 3dB per octave.

It is called pink noise because it is halfway between white noise and Brownian noise, also called red noise or 1/f^2 noise.

If you want some interesting curiosities...

It is not difficult to generate these noises; in fact, white noise was used (at very low volumes) to simulate a beach environment, with sea waves breaking on the sand; it was indeed used to help those suffering from sleep disorders to sleep.

Noises like pink and red (which are more aggressive) were not difficult to find within video games on old 8-bit consoles to simulate audience applause.

An interesting and complex document regarding:

http://www.scholarpedia.org/article/1/f_noise#Music.2C_time_perception.2C_memory.2C_and_reaction_times

more in-depth information here

http://classes.yale.edu/fractals/Panorama/Music/OneOverFMusic/OneOverFMusic.html

Great, is there no one who can find similar material on disharmony? I would need it for my thesis. I searched the Internet and found some interesting documents, but further insights never hurt

What is the subject of your thesis?

If I may ask

Of course, it's not exactly a state secret

I will take care of modeling and, if there is time, also implementing software for piano tuning that has good human-machine interaction, suggesting and instructing the human on the harmonic ratios to be played for the software tuner to listen to; essentially, I want to try to create software capable of dividing the octave as the human ear does, and then proceed in different ways. The problem arises for me more so in the higher registers, and I still need to do some experimentation in MATLAB to try to find a way out. After tuning the piano properly, I will describe the electroacoustic and IT standards for creating a piano sound library. Practically, I want to undertake a journey regarding the piano from preparation to use in both digital and acoustic contexts.

In general, these articles also seem very well made to me

http://en.wikipedia.org/wiki/Musical_acoustics

http://it.wikipedia.org/wiki/Psicoacustica

jack wrote:

I have a curiosity, why is it called white noise?

I am reporting these useful sites for those interested in the subject of Acoustics

http://www.maurograziani.org/text_pages/acoustic/acustica/MG_Acustica01.html

http://www.acs.psu.edu/drussell/demos.html

http://fisicaondemusica.unimore.it/#Il_suono_e_la_sua_percezione

Simon, why does the problem occur mainly at the top?

Why frequencies are exponential. The frequency difference between an octave below and an octave above is very different. For example, 50 Hz - 100 Hz (octave below) has only 50 Hz of bandwidth between the two notes of the octave interval, while 2000 Hz - 4000 Hz (octave above) has 2000 Hz of bandwidth. You understand well that with such fast oscillations, even the beats reported up there should be very fast; it's a pity that the human ear can only perceive beats (even if of the second order or of order n to generalize) if the difference between the frequencies generating the beat does not exceed 15 Hz. Above that, it is impossible; we are well beyond it. One might think, however, that the microphone could still count these fast beats because it does not behave like the human ear, but there is another problem: namely, that beats of order n originate between the fundamental sound of one note and the nth-order overtone of the other. Sometimes these overtones are not exactly those immediately adjacent to the first multiples of the fundamental, and therefore for high notes they could result out of range even for microphones that have a passband up to 20,000 Hz, but by 18,000 Hz they are already quite weak. From this arises the problem of finding a method to model through electroacoustics a system that is capable of being sensitive to these frequencies, or a mathematical algorithm that relates different sounds to examine the note to be tuned so as to be able to treat it mathematically and tune it successfully by emulating the human ear. Which is not easy. Down low this thing is simpler because even the beats gradually slow down. In a range from 0 to 15 Hz as a modulating function of the beat, there are no problems even for the ear. Below, the ear can listen to tenths since it is difficult for a human being to count very slow beats. An algorithm that examines a signal coming from a microphone does not have these problems.

Everything is clear, thank you. And how to determine which overtones they are?

TheSimon wrote:

I will take care of modeling and, if there is time, also implementing a piano tuning software that has good human-machine interaction, suggesting and instructing the human on the harmonic ratios to be played for the software tuner to hear; essentially, I would like to try to create software capable of dividing the octave as the human ear does, and then proceed in different ways.

And - out of curiosity - have you also evaluated temperaments that do not keep the octave ratio fixed (like CHAS?)

RedScharlach wrote:

And - just out of curiosity - have you also evaluated temperaments that do not maintain a fixed octave ratio (like CHAS?)

I had opened a topic on the subject

http://www.pianoconcerto.it/forum/index.php?/topic/906-il-temperamento-chas/

I think Simone has studied one of the latest documents

@micamahler

It depends on which notes you play. If you play an'octave, the beats are between the second harmonic of the lowest note and the fundamental of the higher note that makes up the octave. But there are cases where beats can be generated between higher harmonics (actually partials).

@Redscharlach

For the moment no, it will already be very difficult to manage to implement even the actual software compared to the thesis; for now, I will only examine the tempered system. Nothing excludes that the matter could later be expanded and integrated with other tuning systems.

@Trade1

Yes, I had seen it quickly rather than having studied it; think that your report comes at just the right time because there is a lot of material in that thesis that I could study to define mine. Thanks for reminding me...

Think that Capurso (alfcap) is also one of the forum members

Your thesis deals with a truly interesting subject...

In which cases do beats occur between the upper partials? If the subject is of excessive complexity to be synthesized, I understand and feel free to skip the explanation.

Another question though!!! How do you plan to solve the out-of-range problem regarding frequencies around 20Khz?

(A funny hypothesis would be to bring a dog along... )

I am finishing my thesis for the electroacoustic systems and components exam. As soon as I have finished it, I will send it to you. Everything is written there in quite a detailed manner. Obviously, it is only the thesis for an exam, not the degree thesis, where I will be much more precise instead. To explain the problem that arises, it is more than sufficient nonetheless.

I will understand very little given my enormous gaps in billions of subjects, but I will read it with extreme interest. Thank you.