More than one instrument can play at the same time, they just can't begin at the same time:
This depends on the capabilities of the performing synthesizer, but the commonly used Microsoft GS Wavetable SW Synth is able to perform this. Some synths don't react well (audibly) when this kind of thing is performed.
Title: Re: Changing instrument sound then back again within same song.
Post by: Warren Porter on 2009-09-22 11:39 AM
Check measure 66 of Andante Cantible (http://nwc-scriptorium.org/class5.html#Tchaikovsky). 2nd Violin, Viola, and Cello change to pizzacato strings and return to their original instrument for the arco near the end of the piece.
Title: Re: Changing instrument sound then back again within same song.
Post by: Rick G. on 2009-09-24 05:23 PM
Some synths don't react well (audibly) when this kind of thing is performed.
All synths should play my first clip properly. I don't know of any that object to the 2nd.
The issue is discussed in Response to Program Changes here: www.midi.org/techspecs/gmguide2.pdf See the 16th page of the document. It is called page 12 (https://forum.noteworthycomposer.com/?topic=3007.msg17961#msg17961). (https://forum.noteworthycomposer.com/Themes/default/images/post/wink.gif)
Title: Re: Changing instrument sound then back again within same song.
Post by: NoteWorthy Online on 2009-09-24 09:21 PM
We have a couple of synths here, including two rather high end ones, that cough on the second clip where overlapping sounds using different instruments on the same MIDI channel occur. Specifically, there is an audible glitch or artifact in the performance of the second clip. The exact nature of the artifact seems to depend on the first and second instrument.
Note that the GM program change reference is on page 12.