Mono to stereo enhancement

Hello everyone,
This is not directly related to Mac os, but I did not find on which part of the forum I can ask my question (it’s not audiobook, nor music).

For a personal work I want to use the sound of a thunderstorm that I recorded in 2013, with a Shure SM 58 microphone connected in XLR to a Tascam DR 100, so in mono, 96KHz, 24 Bits.

My current problem is that I would like to “transform” this sound into stereo.
Unfortunately I find it “flat”, “without relief”… it lacks something…
To give it some depth, I tried several solutions but nothing satisfactory.

I duplicated the track, then joined it in stereo to apply the effects “pseudo-stereo”, “Stereo Butterfly”, “Stereo Widener”, “Panning Nyquist”, “Channel Mixer” with different precepts, I applied an equalizer, a reverb… doing lots of tests…
I duplicated the mono track and shifted them by a few milliseconds, I applied an equalizer, a reverb… doing lots of tests… on one or the other track…

Nothing did, I am always disappointed by the rendering, I arrive at the limit of my possibilities of “sound engineering” neophyte.
So I turn to you to know what solutions the Audacity community can offer me, thank you.

This is the sound:

Audacity 3.2.4
Macbook pro 15 inch (2018) Ventura (13.2) 2,6 GHz Intel Core i7, 32 GB 2400 MHz DDR4

I did something similar once with a mono wave sound file. It was a pretty-long file so I had a lot to work with. And it was a long time ago so I don’t remember all of the details.

I “cut” the recording and into (at least) 3 pieces. Then I “spliced” it back together in different sequences (probably with crossfades) so I essentially had 3 different recordings. Then I mixed them left, right, and center. (I guess one of them was the original.)

As you may know, with 2-chanel stereo “center” just means left & right are identical. And mixing is summation so when you mix two tracks (left+center) and (right+center) you’ll need to reduce the volumes by -6dB (50%) if they are 0dB to begin with.

I applied an equalizer, a reverb… doing lots of tests… on one or the other track…

You don’t really get reverb outdoors but it might “add something” if you don’t over-do it. Some echo might also be “interesting” and you can echo from one channel to the other but that probably needs to be subtle too, and maybe not constant or consistent through the whole recording.

Another thing you can do if you cut & splice, etc., to make multiple different tracks is create an out-of-phase stereo track that’s identical on the left & right, but with one channel inverted. That will create a “spacey-phasey” sound. It’s a way to make a “stereo sound” but it’s a little weird and the bass soundwaves get canceled (a problem with thunder) so I don’t recommend it for the whole recording but it’s OK if you want to mix-in one track that way. (If the left & right are identical and out-of-phase, they will cancel to complete-silence on a mono system.)

It lacks frequencies above 11kHz …
Freesound frequency-ruler indicates nothing above 11kHz.png

An EQ boost >11kHz won’t help: there’s nothing there. Perhaps an exciter to add those high frequencies.
[ An EQ boost <100Hz will help make it more powerful ]

If you want realism need different amounts of pseudo-stereo at different frequencies.

There is a free version of ozone imager, but you can’t adjust the frequencies it’s applied to

Perhaps an exciter to add those high frequencies.

There is a Nyquist “exciter” plug-in they call a [u]Harmonic Enhancer[/u]. If should work well with this kind of sound if you want to add some “crispness” or “sparkle” to the high frequencies.

Many thanks to both of you for your insights…
I will try again, thanks to the information and other tips you gave me.

Two points though, Trebor:

1 - you have highlighted the frequency at which the recording was made: 96,000 Hz, does that matter?

2 -you tell me, and I’ve seen it myself, that “It lacks frequencies above 11kHz …”, according to what we see on the freesound spectrogram, but if I do it from the same file on Audacity, this is what I get:
I’ve got a link to a download of the file, Flac, valid for one week, if needed I can give a new link afterwards:

Thanks to the Audacity community and to you two in particular for this question.

Audacity 3.2.4
Macbook pro 15 inch (2018) Ventura (13.2) 2,6 GHz Intel Core i7, 32 GB 2400 MHz DDR4

96,000 Hz sample-rate means there should be content up to 48kHz.

Within the the dynamic-range of the Freesound spectrogram >11kHz is negligible.

Having now heard the FLAC, IMO the main problem is lack of bass (<200Hz),
which is fixable with equalization, see …
I used Ozone Imager & Valhalla SuperMassive add pseudo-stereoness.
The Valhalla plugin High EQ set to 200Hz so it will only effect the bass,
(delay time ~500ms, stereo width 50%).
before-after bass-boost.gif

Hi there,
Sorry for my late reply,

Thank you very much Trebor for your advice, with Valhalla SuperMassive the Ozone Imager are really the effects I needed for this particular sound, I still have a lot of work to do on this sound to get close to what I want but you have really put me on the right track.
I started with your settings and then, little by little, I’m moving towards the idea I have of what my sound should sound like… thanks again…
I also liked what you did with the sound I shared, and thank you for keeping it CC-BY-NC
Take care