In some sense, any modifications of the waveform "makes one instrument sound like another" think of all of the effects pedals used by electric guitarists.
More specifically, various flavors of fuzz pedals give results that start to resemble horns or strings, c.f. Even if they don’t accurately capture "the real thing",
at the very least it's somewhat evocative of a different instrument.
In more recent times, there are more direct modeling approaches, mostly by EHX to make guitars sound like other instruments in a passable manner, e.g.
music.stackexchange.com/users/2639/Dave
Yes, you can modify the waveform.
But it might not make it sound like another instrument as much as you hoped.
A surprising amount of the 'sound' of an instrument is contained in the attack portion of the note, the complex waveform before the relatively consistent waveform of the sustain.
This is why the 'hybrid' synthesis of instruments like the Roland D50 and Yamaha SY range was
so successful - a short sampled attack was combined with a synthesized sustain.
And why the facility to draw a waveform on the screen of a Fairlight was not all that useful.
When turning one instrument into another, replacement of the attack will be more important than modifying the sustain.
music.stackexchange.com/users/17003/Laurence Payne
Izotope Iris 2 is a vst/AU plugin that has a “spectrogram” which allows you to edit the transients and shape of any waveform.
It is multi-Timbral and has 4 Sampling engines.
You can load the respective samples and blend the waveforms.
The editing tools are unique as you edit the waveform with graphical tools such as paint, lasso, erase, etc.
music.stackexchange.com/users/52672/nexogen.io
It is not strictly necessary to use post-processing.
I heard a skilled violinist play a short tune in double-stops that sounded almost exactly like a bagpipe.
A 'very non-skilled' soprano sax sounds like an oboe with a bad head cold :-) .
Here
and there composers have written parts for 2 or 3 woodwinds such that the combined output sounds like some other (usually wind) instrument.
music.stackexchange.com/users/6275/Carl Witthoft
It's certainly possible to morph from one sound to another - this can be done using a technique as simple as cross-fading samples, or by doing an additive resynthessis of each sound and slowly changing from one spectrum to another.
Bear in mind that even the sound of a single instrument isn't defined by a single waveform or spectrum - most instruments' spectra change over time.
music.stackexchange.com/users/18896/topo Reinstate Monica
An instrument's distinctive "sound" comes from its timbre which comes from its various harmonics and these in turn affect the shape of the waveform.  As such, I feel like it would be possible for software to be used (fourier transform?) to modify one instrument's waveform to resemble another instrument's shape and thus "sound" like it.  Not sure if anyone here has any experience with this
Is it possible to modify an instrument's waveform to sound like another?
music.stackexchange.com
<software><tone><harmonics>
music.stackexchange.com/questions/95186
music.stackexchange.com/users/66298/Nicholas Xie
It's certainly possible to morph from one sound to another - this can be done using a technique as simple as cross-fading samples, or by doing an additive resynthessis of each sound and slowly changing from one spectrum to another.  Bear in mind that most instruments' spectra change over time. It's certainly possible to morph from one sound to another
It's certainly possible to morph from one sound to another. Bear in mind that even the sound of a single instrument isn't defined by a single waveform or spectrum. Most instruments' spectra change over time.