MSP Filter Tutorial 5: Parallel Filters - Revision history

Gtaylor@rtqe.net: /* The impulse */

2012-08-13T15:24:37Z

‎The impulse

Admin at 21:03, 25 June 2012

2012-06-25T21:03:52Z

Admin: Created page with "Click here to open the tutorial patch: 05fParallelFilters.maxpat In this tutorial, we'll look at creating ''networks'' of filters to make complex, time-varying timbres ..."

2012-06-22T21:21:47Z

Created page with "Click here to open the tutorial patch: 05fParallelFilters.maxpat In this tutorial, we'll look at creating ''networks'' of filters to make complex, time-varying timbres ..."

New page

Click here to open the tutorial patch: [[05fParallelFilters.maxpat]]

In this tutorial, we'll look at creating ''networks'' of filters
to make complex, time-varying timbres using an oscillator input.

===The impulse===

Look at the tutorial patch. It contains a few sound-producing
objects connected to a network of filter objects: three {{maxword|name=reson~}}
objects in parallel and a {{maxword|name=lores~}} object in series with their
outputs. The audio input for the filter network comes from a {{maxword|name=receive~}} object named <code>filterin</code>, allowing us to generate signals for our filters remotely.

* Turn on the audio in the patcher by clicking on the {{maxword|name=ezdac~}} object. At the bottom of the patcher,
adjust the {{maxword|name=number}} box labeled 'Dry Volume'. In the area of
the patcher labeled <code>1</code>, click the {{maxword|name=button}} attached to
the {{maxword|name=click~}} object. As per its name, you should hear a click!

The {{maxword|name=click~}} object generates a constant signal of <code>0</code>.
When you sent it a <code>bang</code> message, it outputs a ''single
sample'' of value <code>1</code>, then returns to sending <code>0</code>'s.
This is called an ''impulse'', and in an idea world generates
an eve. spread of energy across all frequencies; we could think
of it as the shortest possible burst of white noise we can create
in our digital system. Sending a click through a filter returns
a sound that has the exact frequency characteristics of that filter.
We call this taking the ''impulse response'' of a signal chain.

* Click on a note in the {{maxword|name=kslider}} object at the top of the
tutorial patcher in the area labeled <code>2</code>. You should hear a
sawtooth wave fade in and out with a smooth envelope.

The {{maxword|name=saw~}} object in our patcher is in a signal chain where
it has an envelope (controlled by a {{maxword|name=function}}, a {{maxword|name=line~}},
and a {{maxword|name=*~}} object). If we adjust the {{maxword|name=function}} object,
we can change the shape of the note that gets fired each time we
click on a key in the {{maxword|name=kslider}} object.

===A network of filters===

* Turn down the 'Dry Volume' and turn up the {{maxword|name=number}} box
labeled 'Filtered Volume' at the bottom of the patcher. In the
patcher area labeled <code>3</code>, click in the {{maxword|name=number}} box
labeled 'Vowel'. Enter <code>0</code> in the {{maxword|name=number}} box and hit
return. The <link type="refpage" name="number">number box</link> objects connected to the {{maxword|name=line~}} objects
below should read <code>270., 2290., and 3010.</code>. Click on
the {{maxword|name=kslider}} to play some notes. Click in the 'Vowel'
{{maxword|name=number}} box and enter different values between <code>0</code> and
<code>9</code> and listen to the results. Double-click the {{maxword|name=coll}}
object named <code>formants</code> and look at the contents.

The {{maxword|name=coll}} object in our patcher contains ten lists of frequency
values which correspond to the average ''formats'' for vowels in
the English language ("ooo", "eee", "ah", etc.). In human speech,
our lungs project air through our vocal chords, which modulate the
air pressure into a regular waveform. Our mouth shapes this waveform,
filtering the signal based on the shape of our mouth. These
vocalizations can be modeled as sets of three bandpass filters
tuned to different frequencies, creating a simalcrum of the sound
our voice makes. The shaping of a sound in this manner is
called ''formant'' filtering, and can be created in MSP using
the circuit in our tutorial patcher.

* In the lower-right of the tutorial patcher, adjust the {{maxword|name=number}} box
labeled 'Q' to <code>30.</code>. Click the {{maxword|name=toggle}} box attached to
the {{maxword|name=metro}} object above labeled <code>Random?</code>. Play some
notes on the {{maxword|name=kslider}}.

Tightening the Q on our format filters makes the sound more
obviously 'vocal', as the resonation of the filters cuts out any
extraneous energy from our sawtooth waveform.

* In the patcher area labeled <code>4</code>, adjust the {{maxword|name=number}} box
labeled 'Cutoff frequency' to <code>5000</code>. Play some notes.
Adjust it down to something low, like <code>200</code>.

The output of our formant filters feed into a lowpass filter
controlled by a {{maxword|name=lores~}} object. This cuts the treble from
out sawtooth after it passes through the bandpass network of the
{{maxword|name=reson~}} objects. Changing this value also changes the quality
of the vocal model.

* Adjust the values of the patcher to experiment with different ways to
create a 'singing voice' out of a sawtooth wave and a filter network.
The {{maxword|name=line~}} objects in the patcher attached to the filters
control the interpolation between settings. If you unlock the patcher
and change the second value in the {{maxword|name=message}} boxes, you can
make the transitions smoother or more abrubt. Using the {{maxword|name=click~}}
object, see how the different filter settings sound when driven by an
impulse.

===Summary===

The filter objects in MSP can be connected into networks of filters that
can be used in all manner of interesting ways. Bandpass filters (such
as {{maxword|name=reson~}}) can be used in parallel to simulate the 'formants'
of instruments or human speech. The {{maxword|name=click~}} object allows you to
test the ''impulse response'' of a filter network by sending a single
positive sample through it, generating a pure impression of the frequency
response of the filter.

===See Also===

{{maxword|name=click~}} - Create an impulse

[[Category:Teaching Material]]

@@ Line 5: / Line 5: @@
 ===The impulse===
-Look at the tutorial patch. It contains a few sound-producing objects connected to a network of filter objects: three {{maxword|name=reson~}} objects in parallel and a {{maxword|name=lores~}} object in series with their outputs. The audio input for the filter network comes from a {{maxword|name=receive~}} object named <code>filterin</code>, allowing us to generate signals for our filters remotely.
+Look at the tutorial patch. It contains several sound-producing objects connected to a network of filter objects: three {{maxword|name=reson~}} objects in parallel and a {{maxword|name=lores~}} object in series with their outputs. The audio input for the filter network comes from a {{maxword|name=receive~}} object named <code>filterin</code>, allowing us to generate signals for our filters remotely.
 * Turn on the audio in the patcher by clicking on the {{maxword|name=ezdac~}} object. At the bottom of the patcher, adjust the {{maxword|name=number}} box labeled 'Dry Volume'. In the area of the patcher labeled <code>1</code>, click the {{maxword|name=button}} attached to the {{maxword|name=click~}} object. As per its name, you should hear a click!

@@ Line 1: / Line 1: @@
 Click here to open the tutorial patch: [[05fParallelFilters.maxpat]]
-In this tutorial, we'll look at creating ''networks'' of filters
+In this tutorial, we'll look at creating ''networks'' of filters to make complex, time-varying timbres using an oscillator input.
 to make complex, time-varying timbres using an oscillator input.
 ===The impulse===
-Look at the tutorial patch. It contains a few sound-producing
+Look at the tutorial patch. It contains a few sound-producing objects connected to a network of filter objects: three {{maxword|name=reson~}} objects in parallel and a {{maxword|name=lores~}} object in series with their outputs. The audio input for the filter network comes from a {{maxword|name=receive~}} object named <code>filterin</code>, allowing us to generate signals for our filters remotely.
 objects connected to a network of filter objects: three {{maxword|name=reson~}}
 objects in parallel and a {{maxword|name=lores~}} object in series with their
 outputs. The audio input for the filter network comes from a {{maxword|name=receive~}} object named <code>filterin</code>, allowing us to generate signals for our filters remotely.
-* Turn on the audio in the patcher by clicking on the {{maxword|name=ezdac~}} object. At the bottom of the patcher,
+* Turn on the audio in the patcher by clicking on the {{maxword|name=ezdac~}} object. At the bottom of the patcher, adjust the {{maxword|name=number}} box labeled 'Dry Volume'. In the area of the patcher labeled <code>1</code>, click the {{maxword|name=button}} attached to the {{maxword|name=click~}} object. As per its name, you should hear a click!
 adjust the {{maxword|name=number}} box labeled 'Dry Volume'. In the area of
 the patcher labeled <code>1</code>, click the {{maxword|name=button}} attached to
 the {{maxword|name=click~}} object. As per its name, you should hear a click!
-The {{maxword|name=click~}} object generates a constant signal of <code>0</code>.
+The {{maxword|name=click~}} object generates a constant signal of <code>0</code>. When you sent it a <code>bang</code> message, it outputs a ''single sample'' of value <code>1</code>, then returns to sending <code>0</code>'s. This is called an ''impulse'', and in an idea world generates an eve. spread of energy across all frequencies; we could think of it as the shortest possible burst of white noise we can create in our digital system. Sending a click through a filter returns a sound that has the exact frequency characteristics of that filter. We call this taking the ''impulse response'' of a signal chain.
 When you sent it a <code>bang</code> message, it outputs a ''single
 sample'' of value <code>1</code>, then returns to sending <code>0</code>'s.
 This is called an ''impulse'', and in an idea world generates
 an eve. spread of energy across all frequencies; we could think
 of it as the shortest possible burst of white noise we can create
 in our digital system. Sending a click through a filter returns
 a sound that has the exact frequency characteristics of that filter.
 We call this taking the ''impulse response'' of a signal chain.
-* Click on a note in the {{maxword|name=kslider}} object at the top of the
+* Click on a note in the {{maxword|name=kslider}} object at the top of the tutorial patcher in the area labeled <code>2</code>. You should hear a sawtooth wave fade in and out with a smooth envelope.
 tutorial patcher in the area labeled <code>2</code>. You should hear a
 sawtooth wave fade in and out with a smooth envelope.
-The {{maxword|name=saw~}} object in our patcher is in a signal chain where
+The {{maxword|name=saw~}} object in our patcher is in a signal chain where it has an envelope (controlled by a {{maxword|name=function}}, a {{maxword|name=line~}}, and a {{maxword|name=*~}} object). If we adjust the {{maxword|name=function}} object, we can change the shape of the note that gets fired each time we click on a key in the {{maxword|name=kslider}} object.
 it has an envelope (controlled by a {{maxword|name=function}}, a {{maxword|name=line~}},
 and a {{maxword|name=*~}} object). If we adjust the {{maxword|name=function}} object,
 we can change the shape of the note that gets fired each time we
 click on a key in the {{maxword|name=kslider}} object.
 ===A network of filters===
-* Turn down the 'Dry Volume' and turn up the {{maxword|name=number}} box
+* Turn down the 'Dry Volume' and turn up the {{maxword|name=number}} box labeled 'Filtered Volume' at the bottom of the patcher. In the patcher area labeled <code>3</code>, click in the {{maxword|name=number}} box labeled 'Vowel'. Enter <code>0</code> in the {{maxword|name=number}} box and hit return. The <link type="refpage" name="number">number box</link> objects connected to the {{maxword|name=line~}} objects below should read <code>270., 2290., and 3010.</code>. Click on the {{maxword|name=kslider}} to play some notes. Click in the 'Vowel' {{maxword|name=number}} box and enter different values between <code>0</code> and <code>9</code> and listen to the results. Double-click the {{maxword|name=coll}} object named <code>formants</code> and look at the contents.
 labeled 'Filtered Volume' at the bottom of the patcher. In the
 patcher area labeled <code>3</code>, click in the {{maxword|name=number}} box
 labeled 'Vowel'. Enter <code>0</code> in the {{maxword|name=number}} box and hit
 return. The <link type="refpage" name="number">number box</link> objects connected to the {{maxword|name=line~}} objects
 below should read <code>270., 2290., and 3010.</code>. Click on
 the {{maxword|name=kslider}} to play some notes. Click in the 'Vowel'
 {{maxword|name=number}} box and enter different values between <code>0</code> and
 <code>9</code> and listen to the results. Double-click the {{maxword|name=coll}}
 object named <code>formants</code> and look at the contents.
-The {{maxword|name=coll}} object in our patcher contains ten lists of frequency
+The {{maxword|name=coll}} object in our patcher contains ten lists of frequency values which correspond to the average ''formats'' for vowels in the English language ("ooo", "eee", "ah", etc.). In human speech, our lungs project air through our vocal chords, which modulate the air pressure into a regular waveform. Our mouth shapes this waveform, filtering the signal based on the shape of our mouth. These vocalizations can be modeled as sets of three bandpass filters tuned to different frequencies, creating a simalcrum of the sound our voice makes. The shaping of a sound in this manner is called ''formant'' filtering, and can be created in MSP using the circuit in our tutorial patcher.
 values which correspond to the average ''formats'' for vowels in
 the English language ("ooo", "eee", "ah", etc.). In human speech,
 our lungs project air through our vocal chords, which modulate the
 air pressure into a regular waveform. Our mouth shapes this waveform,
 filtering the signal based on the shape of our mouth. These
 vocalizations can be modeled as sets of three bandpass filters
 tuned to different frequencies, creating a simalcrum of the sound
 our voice makes. The shaping of a sound in this manner is
 called ''formant'' filtering, and can be created in MSP using
 the circuit in our tutorial patcher.
-* In the lower-right of the tutorial patcher, adjust the {{maxword|name=number}} box
+* In the lower-right of the tutorial patcher, adjust the {{maxword|name=number}} box labeled 'Q' to <code>30.</code>. Click the {{maxword|name=toggle}} box attached to the {{maxword|name=metro}} object above labeled <code>Random?</code>. Play some notes on the {{maxword|name=kslider}}.
 labeled 'Q' to <code>30.</code>. Click the {{maxword|name=toggle}} box attached to
 the {{maxword|name=metro}} object above labeled <code>Random?</code>. Play some
 notes on the {{maxword|name=kslider}}.
-Tightening the Q on our format filters makes the sound more
+Tightening the Q on our format filters makes the sound more obviously 'vocal', as the resonation of the filters cuts out any extraneous energy from our sawtooth waveform.
 obviously 'vocal', as the resonation of the filters cuts out any
 extraneous energy from our sawtooth waveform.
-* In the patcher area labeled <code>4</code>, adjust the {{maxword|name=number}} box
+* In the patcher area labeled <code>4</code>, adjust the {{maxword|name=number}} box labeled 'Cutoff frequency' to <code>5000</code>. Play some notes. Adjust it down to something low, like <code>200</code>.
 labeled 'Cutoff frequency' to <code>5000</code>. Play some notes.
 Adjust it down to something low, like <code>200</code>.
-The output of our formant filters feed into a lowpass filter
+The output of our formant filters feed into a lowpass filter controlled by a {{maxword|name=lores~}} object. This cuts the treble from out sawtooth after it passes through the bandpass network of the {{maxword|name=reson~}} objects. Changing this value also changes the quality of the vocal model.
 controlled by a {{maxword|name=lores~}} object. This cuts the treble from
 out sawtooth after it passes through the bandpass network of the
 {{maxword|name=reson~}} objects. Changing this value also changes the quality
 of the vocal model.
-* Adjust the values of the patcher to experiment with different ways to
+* Adjust the values of the patcher to experiment with different ways to create a 'singing voice' out of a sawtooth wave and a filter network. The {{maxword|name=line~}} objects in the patcher attached to the filters control the interpolation between settings. If you unlock the patcher and change the second value in the {{maxword|name=message}} boxes, you can make the transitions smoother or more abrubt. Using the {{maxword|name=click~}} object, see how the different filter settings sound when driven by an impulse.
 create a 'singing voice' out of a sawtooth wave and a filter network.
 The {{maxword|name=line~}} objects in the patcher attached to the filters
 control the interpolation between settings. If you unlock the patcher
 and change the second value in the {{maxword|name=message}} boxes, you can
 make the transitions smoother or more abrubt. Using the {{maxword|name=click~}}
 object, see how the different filter settings sound when driven by an
 impulse.
 ===Summary===
-The filter objects in MSP can be connected into networks of filters that
+The filter objects in MSP can be connected into networks of filters that can be used in all manner of interesting ways. Bandpass filters (such as {{maxword|name=reson~}}) can be used in parallel to simulate the 'formants' of instruments or human speech. The {{maxword|name=click~}} object allows you to test the ''impulse response'' of a filter network by sending a single positive sample through it, generating a pure impression of the frequency response of the filter.
 can be used in all manner of interesting ways. Bandpass filters (such
 as {{maxword|name=reson~}}) can be used in parallel to simulate the 'formants'
 of instruments or human speech. The {{maxword|name=click~}} object allows you to
 test the ''impulse response'' of a filter network by sending a single
 positive sample through it, generating a pure impression of the frequency
 response of the filter.
 ===See Also===