Impluse Response different with measurements

laidick

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Jun 12, 2019
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Hi
This is my first post here regarding impluse response.
I have measurement my Left speaker with 3 different frequency range:
10hz - 500hz
10hz - 1000hz
10hz - 20000hz
There frequency response looks inline in the overlapping range.
However the impluse response has so much difference. I expect the ETC should have similar time v.s. impluse since speed of sound are the same in different frequency range.

May I know why? I may have misunderstand this chart. I would like to use this IR to calculate my in room first reflection .

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John Mulcahy

REW Author
Joined
Apr 3, 2017
Messages
1,875
Measuring over different frequency ranges affects the information available to produce the impulse response. If you only measure to a few hundred Hz there is no information available for the high frequency content of the impulse response. To examine reflections make full range measurements.
 

laidick

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Thanks for your reply.
Should we always assume measuring impluse response to find reflection, we have to always use 10-20k?
 

laidick

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So, would you please also explain why the impluse seems to be narrower when I am using wider frequency range ?
 

John Mulcahy

REW Author
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1,875
The rate at which the signal can change depends on its bandwidth. The lower the high frequency content the slower it changes, and vice versa.
 

laidick

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Jun 12, 2019
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Dear John,

Thank you so much for your kind explanation.
I enjoy using REW so much.

Cheers,
Dick
 
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