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Sorry if it might sound a bit of trivial to some of you peeps..I don't get what the author wants to say with this:

" To represent the amplitude envelope,we will continue to use the waveform view,but now we "zoom out" to look at changes in amplitude at the timescale of the note(I also don't know if he still means the duration of the note by using the word "timescale"?) "

He also mentions in a figure that the "zoom out" from individual cycles of a waveform is used to see the amplitude envelope.

Thanks for your attention!

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If you are looking at a waveform in an extremely zoomed-in state, you see individual cycles of the sound pressure which are essentially an overlay of different waveforms. An example where the advice is particularly relevant if you are looking at "noisy" sound like a cymbal or a gong or a drum. In that case, looking at a resolution of a few milliseconds will not show any regular features.

If you now zoom out, looking from "further away", all of those semi-irregular waves compress into something looking more like a solid area than a wavy line.

This area will suddenly cover a great vertical range at the point where the instrument was struck, and as you go to the right, this area will get smaller again over a range of a few seconds.

This outer shape of the waveform curve is what one calls the "envelope". It is quite correlated with the momentarily perceived loudness of a sound.

  • Wow! Your explanation about "zooming out" sounds clearer and more logical,but I'm still a bit unsure about the fact you pointed out(that an envelope correlates with the momentarily perceived loudness)..I mean in the book I'm reading,author says that the physical property of sound,namely amplitude envelope,is related to articulation,and he also mentions that the changes in loudness referred to as articulation occur over larger spans of time..so can we still say that envelope correlates with the momentarily perceived loudness? Please correct me if I'm getting this wrong... – Triscenic Mar 17 '15 at 15:23
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What the author means is that you will zoom to see the amplitude changes of a single note. I personally would have said zoom in rather than zoom out, but I'm not reading the same book as you.

Amplitude envelopes on keyboards and VST instruments typically are applied on a note per note basis.

  • Actually,I thought the same as it's zooming in rather than zooming it out!And what about the note timescale? what does it have to do with amplitude? – Triscenic Feb 15 '15 at 7:05
  • Whether it's zoom in or out depends on what's in the recording in the first place (multiple notes, or one?) and what level of zoom you are at to start with. – topo Reinstate Monica Feb 15 '15 at 13:10
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    What it has to do with timescale is that on a smaller time scale (miliseconds rather than seconds) you will see the quick changes in amplitude – baordog Feb 15 '15 at 17:29
  • I see! Now I can say I understand what the guy meant by using those sentences! I appreciate your explanations,both of ya,baordog and topo morto! – Triscenic Feb 15 '15 at 19:14

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