Effect fading similar to shortwave radio.

I have the pleasure to greet you. I was reading a long time ago in the specifications of a player… about the possibility of “processing” an audio signal, so that it would be similar to the effect of the audio signal coming from a radio in the short band from a very long distance. That “effect”, as if the source of emission had randomly moved closer or further away from the receiver, or the signal had lost its intensity. The melody could be heard, in wide waves, slightly louder or slower. Although I saved the idea somewhere, I can’t get that note, even though I made great efforts. Can someone help me with additional information about a player that has this setting, or at least the correct term. Considering that all efforts were directed to eliminate this “problem”, it may seem curious that I am the one thinking of reproducing it artificially. However, I can’t find any reference about the player or player settings that could simulate this specific fading of radio waves.

Do voices go Chipmunky at some points ? … https://audio.com/anonymous-audio/simulated-am-tuning

Ah… no. Nothing is distorted. Only the volume drops randomly at certain times and at certain levels. It’s hard for me to explain. I don’t speak English at all. Maybe someone can help me with a better explanation. As if you were playing the song on the speaker in the room and then on the one on the terrace! The effect is similar to the long-distance radio programs we used to listen to 40 years ago. I am an obvious nostalgic. In the past, this effect was obtained by moving large paddles in front of the speakers. A few years ago… possibly 10…15, I came across an article in which this function was presented in a player. So it was a concern of people in time for this effect. Unfortunately, I lost the idea. Only now I have time to resume it. Thank you very much.

A delay, with a low-pass filter ? … https://youtu.be/_MZ4hNv0bPc?t=142

Valhalla-freq-echo is a free plugin … https://valhalladsp.com/shop/delay/valhalla-freq-echo/

Listening to short waves /OC/ often gives rise to many phenomena that degrade the quality of sound /speech and music/. The most unpleasant impact is that of fading, followed by sound reverberation and the zone of silence.
Fading can be caused by the weakening of broadcast signals or certain atmospheric or electromagnetic disturbances. It most often affects short waves and consists of a gradual, sporadic or prolonged weakening of a transmitted signal to the point that it becomes incomprehensible and inaudible. It is in most cases the interaction of two or more electromagnetic rays or a rotation of the polarization of the reflected wave. Another cause of the appearance of fading – the action of the Earth’s magnetic field on the ionosphere following which the polarization of the reflected wave outlines a rotational movement around its own polar axis. The polarization also changes following the modification of the concentration of the ionosphere under the impact of the Sun, for example. To reduce the effect of fading, one can use directional antennas, or combine a vertical antenna and a horizontal antenna. The receiver antenna responds to only one type of polarization including automatic amplification control, which helps to attenuate extraneous noise and amplify the sound.

A few words about reverberation which is the product of the reflection of sound on the different walls and surfaces of an enclosed space. Reverberation is usually created from a complex amalgam of echoes (called “reflections”), making the effect homogeneous and diffuse and whose evolution over time is modulated according to the frequency and specific settings. Reverb can be of several types – natural, spring or digital. Regarding the radio, several settings must be taken into account, namely:
• Hight ratio: Determines whether the reverb has a strong high frequency effect.
• Low ratio: Determines whether the reverb has a strong low frequency effect.
• LPF: Frequencies from which the high frequencies are cut in the reverberation (high cut filter).
• HPF: Frequencies at which low frequencies are cut in the reverberation (low-cut filter).

There are also other factors that deteriorate OC reception, such as the quiet zone, to which we will devote another issue.

Emulating earth’s atmosphere + Earth’s magnetic-field is a tall-order.

If generic short-wave tuning sounds are sufficient, there are plenty on freesound …

You can even listen to live short-wave broadcasts via internet browser …

GOOD… WE’RE CLOSING. https://freesound.org/people/csnmedia/sounds/381173/ This is the fading effect. It has a certain charm if it is not so “deep”. In the past, paddles were used that moved in front of the box. A player that KNOWS how to do this to an MP3…etc…? THANK YOU

I think that now I will be better understood what I want. Google translator is not good in technical discussions. I know there is a common player that had this setting. Can Audacity help me? Do you know another player that has this setting? Thank you

“Random Low Pass Filter” is a similar effect … https://wiki.audacityteam.org/wiki/Nyquist_Effect_Plug-ins#Random_Low_Pass_Filter

https ://audio.com/anonymous-audio/random-low-pass-filter-demo

To add heterodyne-whistle & hiss, there is an old free plugin called Plektron Devicer,
(AM Radio is preset #6https://youtu.be/3GNGXXZeW_g?t=404 )
BUT Plektron Devicer is only available as 32-bit plugin, so will only work on 32-bit versions of Audacity.