psychoacoustics

[steevio]

forum's been dead recently, but here's something i think might be of interest to you guys.

you've probably all heard about the 'missing fundamental' effect, which is a well known psychoacoustic effect, but it goes way further than that.

when people say 'use your ears' they arent wrong, because no matter how much you analyse spectra, or plan your chords, notes etc. there are lots of psychoacoustics going on which are often hard to identify unless you get really anal about your harmonics. thats what ive been doing recently.

for instance when you play two notes together which are harmonically related, you dont just hear two notes, you also hear a lower note which is the difference between the two notes.

so say you play a C (130.81 Hz) and a true tritone F# -49cents (179.86 Hz) you also hear a tone 179.86 -130.81 = 49.05 Hz
which is a G, not only that but you hear a tone which is this difference subtracted from the C also, 130.81 - 49.05 = 81.76 Hz which is an E.
so when you play C F#(untempered) you actually hear G E C F#.
those frequnecies will not show up on any spectra, but you hear them, so a true tritone is actually a chord to your brain.

it makes me wonder if a tritone which sounds dischordant to western ears, is actually not dischordant at all, its just that we perceive it as such, if we could really just hear the two frequencies without the psychoacoustic effects, what would they really sound like ?
anyway, i think its worth taking such things into account when composing, especially when using intervals that are very close to their harmonic series counterparts such as perfect 5ths, these will produce strong psychoacoustic lower frequencies which could be cluttering up your bass etc...

[optX]

very interesting topic!

Certain chords are feeling bass-heavier to me than others although there shouldn`t be so much bass produced by those notes. (But it`s not very reproducable for me)
Then I cut the bass but yet I can hear it... I thought I am going to get mad because there is no bass which I can analyze but I can hear it although I cut it away ...

It`s (like Steevio already said) a well-known phenomena. There are a lot of theories around why this happens and how it happens and so on.

A good example is voice on telephone. It`s cut at 300Hz but you can hear voice correct and even identify who is speaking. Men`s fundamental should be around 120Hz and women`s fundemental at 250Hz or so.

Can this topic maybe be related to overtone- vs. fundamental-hearing? I joined a lecture about overtone/fundamental-hearing last year where they did a test with us. Now I know that I am an overtone-hearer. Does that maybe mean that overtone-hearers can harder hear that missing fundamental? (just a wild guess)
Steevio, do you know something about how different people are recognizing a missing fundamental? Is everybody hearing the same regarding to this topic?

[optX]

ok, that`s what wikipedia is saying >

"Research conducted at Heidelberg University, as described in the January 2006 issue of the German audiophile magazine AUDIO, indicates that the general population can be divided into those who perceive missing fundamentals, and those who primarily hear overtones. The magazine article states that the difference between the perceived pitches can be up to 4 octaves."

[steevio]

thats interesting,

so some producers hear them and others dont,
and mastering engineers !

it must be a big advantage to hear them

[optX]

Hmm... both has it`s "benefits".
Overtone-hearers can hear long-lasting tones, low frequencies and timbre/tone color "better".
Fundamental-hearers can handle complex rhythms better and are supposed to be better virtuosos on instruments.

"Indeed, most professional musicians perceive simultaneously both fundamental and spectral pitch from an ambiguous tone, and the subjective differences are rather relative than absolute"
maybe you can exercise your brain so you can hear both. As we know our behaviour programs our brain (builds or delets brain cells and their connections which seems to be matter here)...

"The overall strong separation was most pronounced in the lower (Fig. 1c, spectral frequencies <1,500 Hz, F1,419 = 731.4, P < 0.0001) as compared with the higher spectral frequency range"
regarding to "being an fundamental-hearer may be an advantage for mastering engineers" : Obviously this "phenomenon" doesn`t occur over the whole frequency spectrum. So it`s doubtful speaking in terms of advantage.

found in Nature Neurosciences. Articel is named "Structural and functional asymmetry of lateral Heschl's gyrus reflects pitch perception preference" (http://www.nature.com/neuro/journal/v8/ ... n1530.html)
that`s the survey mentioned on wikipedia (Universität Heidelberg)

Interesting for me is that this survey was made by Med-guys. Most of the time such stuff is discovered by musicologists whereas Med-guys aren`t very much interested in such topics.

The lecture I attended last year was build around the lecturer`s survey which found out that there are more fundamental-hearers than vice versa. In the audience (about 50 people) just two guys were overtone-hearers. Whereas this Heidelberg article says in a short sentence that it was averaged at a unique testing group of about 80 people (If I´ve understood that correct)

[hairblz]

if we could really just hear the two frequencies without the psychoacoustic effects, what would they really sound like ?

I thought it was down to the fact that both frequencies are "sharing" your eardrum at the same time, resulting in rhythmic constructive and destructive interference.

Pan the two frequencies left and right, put on headphones, and the effect disappears.

(I only tried it with 324Hz and 325Hz together, where the 1Hz pulse is obvious when they are together)

[steevio]

if we could really just hear the two frequencies without the psychoacoustic effects, what would they really sound like ?

I thought it was down to the fact that both frequencies are "sharing" your eardrum at the same time, resulting in rhythmic constructive and destructive interference.

Pan the two frequencies left and right, put on headphones, and the effect disappears.

(I only tried it with 324Hz and 325Hz together, where the 1Hz pulse is obvious when they are together)

i think we're talking about something completely different here bro

[hairblz]

i think we're talking about something completely different here bro

Are you sure?

I'm pretty convinced it's the same thing . . . there's a good chance I'm just being slow also

You used the example of playing two tones, and being able to hear the difference between the tones (ie. 325Hz minus 324Hz = 1Hz). This is exactly what I did; I played two tones, 1Hz apart, and there was an audible 1Hz pulse, which went away when I panned the two frequencies.

I don't see where I'm getting confused.

Edit: Looking at the combination tone wikipedia,

http://en.wikipedia.org/wiki/Intermodulation_distortion

Intermodulation distortion: This is the destructive and constructive interference I mentioned.