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#### giordy60

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Discussion Starter · ·
Hello John,
I can not solve this problem:
I measured with REW my listening room and I must say that the measures are not bad but there is one thing I can not understand:
the answer in the environment is good
the level of distortion is acceptable
the impulse response is good
the value is good dell'TR60
the waterfall is acceptable
but on reflection I ETC to 1,93ms and a 5.93 ms that I can not delete.
I tried it with the classical string to figure out where are these thoughts .... but nothing to do.
(I did so: the sound travels 344 meters per second then a millisecond equals 34 cm.
First reflection: 34 X 1.93 = 65.62 cm + (distance monitor - microphone) 208 cm = 273.62)
there is nothing at that distance that generates the reflection.
I enclose the mdat for easy reading
thank you

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#### JohnM

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6,711 Posts
Hi Giordy, your approach is correct, so if the distance from mic to speaker is 2.08m the path travelled by that first reflection at 1.93 ms will be 2.74m. Depending on the height of the mic and speaker drive units, that would be about the distance travelled by sound reflected from the floor. One way to narrow down where a reflection is coming from is to place a very absorbent panel or material in different positions around the mic or the speaker (above, below, left, right) and see which location most reduces the height of the reflection.

#### giordy60

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54 Posts
Discussion Starter · ·
..... One way to narrow down where a reflection is coming from is to place a very absorbent panel or material in different positions around the mic or the speaker (above, below, left, right) and see which location most reduces the height of the reflection.
What can I use as a material to be placed around the mic....use a panel of polyurethane foam + pyramid might be correct for a test ?

#### JohnM

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That should work, something that is a good sound absorber - the more sound it lets through, the less the effect on the peak. You could even use something solid, although it would reflect the sound a create a peak somewhere else you should still be able to see if it affects the peak you are interested in.

#### giordy60

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54 Posts
Discussion Starter · ·
OK, I see what I have at home.
thank you

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