CDP Sound Example – MORPHING

Morphing between similar sounds

SOURCE SOUNDS

stream
crackling

TRANSFORMATION

morph stream to crackling

DESCRIPTION
~ CDP Function: MORPH MORPH ~

• This MORPH function gradually replaces the spectrum of one sound with that of another.
• This process takes account of the fact that the spectrum is constantly evolving over time.
• The timing (start & end) and level of entry (linear or exponential) of the amplitudes and frequencies can be set independently.
• In this example, a double morph is used. In the first morph, the times are set to 3.5 - 6 in a 6.3 sec file, and stagger is set such that the second input comes in at 3 seconds (just before the morph begins). The times for the second morph are 6.5 - 9 because the use of stagger made the output of the first morph 3 seconds longer.
• The amplitude level of the second input enters slowly and then more rapidly increases (exponent = 2). The frequencies of the second input come in steadily in a linear fashion (exponent = 1).
• Simple pre-processing helped improve the perception that a morph was taking place. Firstly, the loudness of the stream was doubled (gain = 2) so that it matched the crackling better. Then the amplitude envelope of the crackling sound replaced that of the stream, producing an interim state in which the stream sounds as if it is being disturbed in some way.
• Finally, the double morph was done: from the stream into this disturbed stream, and then from the result of this morph into the sound of the crackling itself.

Additional Information

PARAMETER SETTINGS
(Click on image to view fullsize)

KEY POINTS

• Morphing creates a smooth but perceptible transition from one sound to another (usually similar) sound.
• The key to morphing lies in what happens in the transition part of the resulting sound. One is meant to perceive that transition, to feel it warping into something different.
• Thus, it is not necessarily meant to sound like a MIX or CROSS of two sounds, where the first flows smoothly into the second. It is the sense of warping out of shape and being reconstituted differently which is the psychoacoustic objective, as clearly seen in the visual dimension.
• The aural process usually needs more time for the transition than the visual one.
• It is not a trivial matter to find an effective way of doing this. Here, the very lively amplitude envelope of the crackling is extracted and replaces the amplitude envelope of the stream (ENVELOPE REPLACE).
• Then stream is morphed with reshaped amplitude envelope stream, with a 3 second stagger to give time for us to hear the stream in its original form before it starts to change. When reshaped amplitude stream comes in, it sounds as if the stream is being disturbed by something.
• The last step is to then morph the result of the first morph (stream to disrupted stream) with the crackling sound, also with a stagger, this time 6 seconds, because the first stagger added 3 seconds to the overall length.
• The final result then is stream to stream disrupted by the crackling envelope to the crackling.
• The morph sounds more than a mere transition or crossfade because we have introduced the perception that the first sound (still perceived as being the first sound) has been disrupted in some way. When the second sound finally emerges, we realise what has caused the disruption. The perception (it seems to me) is of a stream which has been strongly affected by something, goes brittle and then fragments: an audio morph.

SUPPLEMENTARY FILES USED

A behind the scenes amplitude envelope transfer (ENVELOPE REPLACE extracts and superimposes in one operation, creating st6gaeofck6.wav, i.e, 'st6g' with amplitude envelope of 'ck6'.)

DIAGRAM OF THE MORPH

FIRST MORPH                                morph...
[input 1: st6g.ana]                 0____3_3.5____6_6.3
[input 2: st6gaeofck6.ana]          (s=3)0_______________6.3
[morph1->2: st6gmphst6gaeofck6.ana] 0____________________9.3

SECOND MORPH                                        morph...
[input 1: st6gmphst6gaeofck6.ana]   0_____________6_6.5____9_9.3
[input 2: ck6.ana]                  (s=6)         0_______________6.3
[morph 1->2: exmph1.ana]            0_____________________________12.3