Impluse Response different with measurements

laidick

Registered
Thread Starter
Joined
Jun 12, 2019
Messages
4
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 .

14575



14576



14577



14578
 

John Mulcahy

REW Author
Joined
Apr 3, 2017
Messages
7,212
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

Registered
Thread Starter
Joined
Jun 12, 2019
Messages
4
Thanks for your reply.
Should we always assume measuring impluse response to find reflection, we have to always use 10-20k?
 

laidick

Registered
Thread Starter
Joined
Jun 12, 2019
Messages
4
So, would you please also explain why the impluse seems to be narrower when I am using wider frequency range ?
 

John Mulcahy

REW Author
Joined
Apr 3, 2017
Messages
7,212
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

Registered
Thread Starter
Joined
Jun 12, 2019
Messages
4
Dear John,

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

Cheers,
Dick
 
Top Bottom