To create a spectrum that smoothly changes its partial amplitudes over time according to what you read from a data file, start with a MIDIVoice and select Script as the Source. The "instrument" can be the Sound you already have, with
TrackNumber of: {!Fader copies: 65}
in the AmpScale field. Then, in the Script field of the MIDIVoice, you can use something like this (of course substituting the name of your own data file and ensuring that the ranges of your data points are (0,1) or scaling/offsetting them in your Script to make sure they are in the right range for the AmpScale controls. You may prefer to use another way of incrementing time; I just used the line number as the start time in seconds. This assumes that you have 65 or fewer data variables on each line of your text file:
| f params line |
f := 'yourDataFile.txt' asFilename textFileStream.
line := 0.
[f atEnd] whileFalse: [
params := f nextParameters.
1 to: params size do: [ :i |
self controller: (i - 1 of: {!Fader copies: 65}) slideTo: (params at: i) abs byTime: line s].
line := line + 1].