Is this comb filtering?

[Derykus]

This image is a snapshot of me holding out a note while singing very loudly. I can hear the reflections when the vocals are super compressed, and especially so after a phrase.

http://dl.dropbox.com/u/3331450/Comb Filter.bmp

 

[JakeAC5253]

What does it sound like?

 

[xFkx]

WAT

 

[Derykus]

Sorry the image didn't post. I put up a link.

It sounds like if you slapped a very short delay on the track. It's not blatantly obvious and I've gotten away with it for a while, but I'm always looking to improve the quality of my recordings.

Edit: looks like dropbox is down, and that's why the image doesn't appear and the link doesn't work.

 

[JakeAC5253]

Sorry the image didn't post. I put up a link.

It sounds like if you slapped a very short delay on the track. It's not blatantly obvious and I've gotten away with it for a while, but I'm always looking to improve the quality of my recordings.

Edit: looks like dropbox is down, and that's why the image doesn't appear and the link doesn't work.

Lol, actually I saw the image, but even with the image it doesn't help us to answer your question. The only tool that can ACCURATELY and without fail determine phase problems is the ear. Phase issues are going to happen all of the time, and comb filtering is a rather obvious and destructive form of phase issues which will sound very obvious even to the beginner. I can't say definitively whether you are or aren't experiencing comb filtering via the picture that you posted, all EQ curves have peaks and troughs, it's what gives them a unique timbre.

You already indicated that you heard something weird, and "something weird" is how I knew my recordings had phasing issues before I knew what to call it. So lets say for arguments sake that your recording does have phasing issues, try and fix it and see if you can hear an improvement.

 

[TheWinterSnow]

looking at that picture, you do not have comb filtering taking place. Its obvious because the peak frequencies are all relative to the fundamental frequency. This is what makes your voice sound like your voice, versus the sound of a guitar, or a piano all hitting the same note. Now if you are having early reflections, the meter will not pick that up however you will hear it. You need acoustic treatment to take care of that and the meters will not be able to help you in such case as meters only help you with comb filtering. Form the picture and your description you don not have a comb filtering issue, rather an early reflections issue.

 

[JakeAC5253]

looking at that picture, you do not have comb filtering taking place. Its obvious because the peak frequencies are all relative to the fundamental frequency. This is what makes your voice sound like your voice, versus the sound of a guitar, or a piano all hitting the same note. Now if you are having early reflections, the meter will not pick that up however you will hear it. You need acoustic treatment to take care of that and the meters will not be able to help you in such case as meters only help you with comb filtering. Form the picture and your description you don not have a comb filtering issue, rather an early reflections issue.

Comb filtering is the same as early reflections. Like I said you can't tell by the picture because even if an extreme form of comb filtering was occuring, all of the peaks and troughs would still line up in a harmonic fashion according to the eye on a frequency spectrum analyzer, but the ear would know that it was wrong.

 

[-Noodles-]

For their to be comb filtering occurring, two signals need to be present.
the original and a reflected original.

The original comes straight from source, and the reflected original comes in at a later time. When they're combined they summate and at certain frequencies cause cancellation, resulting in comb filtering.

If you only have one vocal track (eg: no parallel processing) then it's extremely unlikely to be comb filtering within the DAW.
If you have a copy of the vocal track being sent either through an external processing unit or auxiliary then there's a chance that's the source of the problem.

To be honest - your picture just looks like a note being held with obvious harmonics and the fundamental present. Comb filtering would result in un-even distribution of harmonics due to those frequencies being 'nulled' by the delayed reflections.

 

[TheWinterSnow]

Comb filtering is the same as early reflections. Like I said you can't tell by the picture because even if an extreme form of comb filtering was occuring, all of the peaks and troughs would still line up in a harmonic fashion according to the eye on a frequency spectrum analyzer, but the ear would know that it was wrong.

Early reflections won't always cause comb filtering especially in larger room and or instruments without a large amount of lows. If the reflection is late enough than it won't necessarily cause comb filtering but can cause an echo. If the delay is small enough for the early reflections their intensity to cause comb filtering will be a lot higher.

What I said before is that there are both early and late reflections in the room that the mic is picking up, while note causing comb filtering, when compressed is amplifying the echo in the room which he is hearing.

Its obvious from the picture that comb filtering is not taking place because the fundamental and its harmonics are all present and not attenuated. If there was a certain harmonic that was attenuated that wasn't divisible by the fundamental, than all orders of that harmonic would be even less than that harmonic and harmonics nearby would have a parabolic of dip in volume which would resemble a comb (hence the name comb filtering).

A comb filtering issue sounds like a flange/phaser type effect which is from early reflections having a very small delay. With the same token, early reflections that have a larger delay will give the audio an echo or delay type of effect.

I keep my previous statement in that the compressor is just amplifying the ambient sound of the room, not comb filtering.

ALSO: The best way to detect comb filtering is to measure a sine sweep from your monitors, if it still looks like the picture above, then yes you have comb filtering, but instruments are supposed to have selective peak resonances.

 

[TheWinterSnow]

To be honest - your picture just looks like a note being held with obvious harmonics and the fundamental present. Comb filtering would result in un-even distribution of harmonics due to those frequencies being 'nulled' by the delayed reflections.

This!

 

[-Noodles-]

@TheWinterSnow - *high five*