Echo and Reverberation
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Transcript of Echo and Reverberation
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SlideSlide 33©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
$c!o
• %cho is audible becausethe speed o& sound isrelativel' slo#( about )**meters per second.
• Click on icon to listen toecho.
Sound Source
Listener
Direct
Sound
Echo
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SlideSlide 44©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Block "ia)ram o* $c!o
• +or the time being( #e #ill consider onl' one echopath.
• ,utput - Input !ela'ed Input.
• /ecause o& losses in the dela'ed path( 0ain 1.
Delay
Input +
+
Simplified Echo
GainDelayed Input
Output
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SlideSlide 55©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
$+uation *or Simli*ied $c!o
)1()(
).()()( N
N
z Gn x
z n xGn xn y−
−
⋅+⋅=
=⋅+=
z -N
x(n) y(n)+
+
Simplified Echo
G.x(n).z -N G
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SlideSlide 66©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Fre+uenc- Resonse
• The &re2uenc' response o& echo can be calculated using the
&ollo#ing .m &ile.
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Fre+uenc- Resonse o* $c!o
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Multile $c!o #at!s
• 3 real room #ill have several echo paths.
Delay1
Input
+
+
Multiple Echo Paths
Gain1
Delayed Input 1 Output
Delay2 Gain2
Delayed Input 2
+
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9/31SlideSlide 99©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Summar- o* $c!o
• The %cho output is derived solel' &rom theinput.
• Certain &re2uencies are attenuated.
• /ecause the poles lie inside the unit circle(echo is stable.
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10/31SlideSlide 1010©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Re%er&eration
• 4everberation is similar to echo( but uses a slightl' di&&erent con&iguration.
• Click on the icon to hear reverberation.
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11/31SlideSlide 1111©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Re%er&eration on Sta)e
Microphone
Performer
LoudspeakerLoudspeaker
Sound reaches the microphone &rom boththe per&ormer and the the loudspeakers.
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©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Block "ia)ram o* Re%er&eration
• ,utput - Input !ela'ed ,utput
Delay
Input Output+
+
Delayed Output
Simplified Revereration
Gain
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©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Simli*ied Re%er&eration $+uation
)1/()()()()( N
N
z Gn x z n yGn xn y
−
−
⋅−=
=⋅⋅+=
! "#
$%n& y%n&+
+
G'y%n&'!"#
Simplified Revereration
G
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©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Matla& Model o* Re%er&eration
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©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Re%er&eration Fre+uenc- Resonse
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©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Summar- o* Re%er&eration
• The output is derived &rom both the input and the previous output.
• 3t certain &re2uencies( the output #ill be ampli&ied.
• /ecause the poles lie on the unit circle( reverberation can become unstable.
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©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Real .orld $c!o and Re%er&eration
• 3 real room #ill have several echo paths.
• 5hen sound is re&lected o&& a sur&ace there #ill be coloration. Certain &re2uencies #ill be absorbed and there #ill be phase changes.
• There&ore( a commercial echo $ reverberation unit #ill contain man' di&&erent dela' paths.
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SlideSlide 1818©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Simulink Models
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SlideSlide 1919©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Simulink Model o* $c!o
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SlideSlide 2020©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Simulink Model o* Re%er&eration
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SlideSlide 2121©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Modi*ications *or TI /71
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SlideSlide 2222©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
/71 "S3 Model o* $c!o
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SlideSlide 2323©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Samlin) and Inte)er "ela-
• The samplingrate is 8*** 9:.
• 3n Integer!ela' o& )***produces a
dela' time o&)***$8*** -*.; seconds.
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SlideSlide 2424©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
/71 "S3 Model o* Re%er&eration
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SlideSlide 2525©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Simulink Model o* Re%er&eration
•
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SlideSlide 2626©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
Introduction to La&orator-
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SlideSlide 2727©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
T!e /omlete Simulink Model
• In the Aaborator' 'ou #ill build a SimulinkBodel &or echo and reverberation.
• ou #ill be able to run di&&erent echo andreverberation e&&ects on the C671 !S".
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SlideSlide 2828©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
/71 "S3 Setu
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SlideSlide 2929©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
T!e /omlete /71 Model
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SlideSlide 3030©© 2007 Texas Instruments Inc,2007 Texas Instruments Inc,
"S3 Sitc! Settin)s
!ecimal S51
*
S51
1
S51
F
S51
!escription
*
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©© 2007 Texas Instruments Inc2007 Texas Instruments Inc
Re*erences
• 3 !igital Signal Drocessing Drimer b' "enSteiglit:. IS/G *H8*;H168)H1.