The possible merits of auto-tune?

[Muleya]

The doppler effect is due to frequency modulation that occurs when the source of sound is moving relative to the one hearing the sound. When a sound is coming towards you, the sound waves are compressed, which in turns increases the frequency and thus the pitch. When it speeds away from you, the sound waves are rarified, which in turns decreasese the frequency and thus the pitch.

A more detailed explanation:

Obviously, sound travels at the speed of sound. But the speed of sound is slow enough that the speed of source of the sound, relative to the one hearing the sound, has a noticeable affect. So when the object is moving towards you, it's the speed of sound PLUS the speed of the object...meaning the sound waves are moving faster, and thus they reach you faster and the time between the sound waves is shorter...i.e., frequency increases, and since pitch is a direct function of frequency, pitch increases. When an object is moving away from you, it's the speed of sound MINUS the speed of the object...meaning the sound waves are moving slower, thus they reach you slower and the time between the sound waves is longer...i.e., frequency decreases and again, since pitch is a direct function of frequency, pitch lowers.

Volume is simply a function of the distance...the closer the source is, the louder. But volume has nothing to do with pitch.

[brent]

Yes it does. I am telling you. Do some research and quit thinking inside the box.

[brent]

By the way, are you among those who think it's a good idea to monitor at 80dB (or I guess 85dB) when mixing in your studio?

I monitor way less than that most of the time when getting a balance, and then closer to it when tracking. Most of the A list guys I have been around are there and louder. I bump it up to 105 or so for some deaf clients short term, but I leave the room. I manage my exposure. I monitor on Focals, Dynaudios, Genelecs, Mackies on remotes and Auratones. They all bring something different to the table. Obviously, they can't all deliver above 90 for long....

Most the mastering guys I know are in the 80 range. There are some old schoolers that still turn out some of the best rock work monitoring above 115. Personally, I think they are deaf by now but they get the work and their rooms sound great from what I hear.

[brent]

BTW guys, you should really talk to an audiologist to learn about how we hear and why changes affect us. You guys are trying to apply clean little cut and paste explanations for the Doppler Effect, etc. That's fine, but there are other contributions to consider....Again, talk someone who is on the cutting edge of R&D.

Read up on Cochlear Implants and how they are implemented. Author Graeme Clark wrote a basic book that explains a bit. In the book there is a section on this topic, how loudness affects pitch and pitch affects loudness.

[Boray]

So when the object is moving towards you, it's the speed of sound PLUS the speed of the object...meaning the sound waves are moving faster, and thus they reach you faster and
...

The waves are not moving faster. The waves just become shorter = higher pitch. Sound can not move faster than the speed of sound. That is why the waves become shorter.

[Boray]

Ok, brent, you got it both right and wrong. You mixed up the Dopper Effect with the Doppler Illusion:

The Doppler Effect is a physical fact because of the speed of sound, it affects the soundwaves and can be recorded with a microphone.

The Doppler Illusion is that the human ear or brain perceives sounds differently because of volume:
http://jneuhoff.com/Doplusion.pdf

Or maybe what that research shows is that the brain hears a doppler effect when it expects one.

Well...

How big would this loudness/pitch change be? Because I can't and have never ever heard a change in pitch when changing the volume of speakers/headphones or whatever.

"Studies with the sounds of musical instruments show less perceived pitch change with increasing intensity. Rossing reports a perceived pitch change of around 17 cents for a change from 65 dB to 95 dB. This perceived change can be upward or downward, depending upon which harmonics are predominant. For example, if the majority of the intensity comes from harmonics which are above 2 kHz, the perceived pitch shift will be upward."
http://hyperphysics.phy-astr.gsu.edu/hb ... pitch.html

And how much is 17 cents then?

"Normal adults are able to recognize pitch differences of as small as 25 cents very reliably."
http://en.wikipedia.org/wiki/Cent_(music)

That's not much... but maybe it's actually even less, because in experiment 3 in the pdf above, they come to the conclusion that this effect only appears with a dynamic volume change (mimicing the doppler effect). When comparing static tones of different volume, the effect wasn't there. Which would mean that this all has nothing at all to do with on-stage monitoring where your monitoring level probably is pretty static.

[brent]

17 cents is drastic! I can't do it now, but when I get home, I will post something at 440 and then something just 3 cents off and you will hear the difference. You are correct. I should have used illusion.

[Boray]

Read up on Cochlear Implants and how they are implemented.

And what electrical stimulation of the cochlear to make deaf hear has to do with all of this... I have no idea...

[Boray]

17 cents is drastic! I can't do it now, but when I get home, I will post something at 440 and then something just 3 cents off and you will hear the difference. You are correct. I should have used illusion.

"The just noticeable difference for this unit is about 6 cents."

[Boray]

Here you can listen to 10 cents difference:
http://en.wikipedia.org/wiki/File:Ten_C ... terval.ogg

[brent]

If a musician cannot hear a 1 cent deviation, then it is time to quit.

You guys need to also read up on Bob Katz. He has a book about digital audio and level practices, documenting the 83dB Dolby standard and then discusses how meters, levels, bits/dynamic range should be related for a good product.

Later, when I return, I will post the medical documentation that ties all of this together for you. Again, if you could be on the other side of the glass, you would be exposed to science and practices used in the hearing health industry that proves the point, loudness effects pitch and pitch loudness. That book I told you about has the chapter in simple terms. You can google it I am sure. You guys are stumbling on what happens outside of the ear in the air, and with that you are limiting yourselves to old technologies and thought processes. We are talking about what happens inside the ear and the brain.

If I were to talk about the inverse square law, I am sure you guys would copy and paste something about that. But we in concert sound business we know how to get around that law, by using line array speakers and microphones, to actually increase SPLs over distance.

[Boray]

If a musician cannot hear a 1 cent deviation, then it is time to quit.

http://en.wikipedia.org/wiki/File:One_Cent_Interval.ogg

I guess it's time to quit then...

[Muleya]

Yes it does. I am telling you. Do some research and quit thinking inside the box.

Show me the formula! I was a math major/physics minor in college and taught high school physics for 6 years...so forgive me for not taking your word for it! I'm certainly no expert, but this isn't my first trip around the block,either! Let's see the proof!!

A little investigating shows there may be a "perceived" change in pitch relative to volume (amplitude), but I don't see any physical way that amplitude can affect frequency, nor am I aware of any formula connecting them.

Thanks for all the reading and research suggestions, but I've got plenty of reading that's not getting done already!!

[Muleya]

So when the object is moving towards you, it's the speed of sound PLUS the speed of the object...meaning the sound waves are moving faster, and thus they reach you faster and
...

The waves are not moving faster. The waves just become shorter = higher pitch. Sound can not move faster than the speed of sound. That is why the waves become shorter.

My bad...that's what I get for replying when I should be in bed! But it is due to the relative movement between the two objects. If the source is moving towards you, it's successively closer each time it emits a wave, so the waves are closer together. Conversely, if it's moving away from you, it's successively further away, so the waves are further apart. And if you are moving, then you encounter the waves at a different rate then they were emitted, with similar results.

[brent]

The problem is, you want a formula for something scientists have yet to understand. I don't have to understand it to know it is true. I go through this all the time with artists and IEMs. Ask any professional artist who uses IEMs and they will confirm it.

John G. Neuhoff- [email protected]
Dept. of Psych., Lafayette College,
Easton, PA 18042

Michael K. McBeath
Dept. of Psych, Kent State University

Popular version of paper 4pPPa3
Presented Thursday Afternoon, June 19, 1997
133rd ASA Meeting, State College, PA
Embargoed until June 19, 1997

When real world physics and our perception of the real world differ, the result is often a perceptual illusion. Most of the time the frequency of a sound (a physical measurement) and the pitch of a sound (a perceptual characteristic) are related. Pitch is our subjective perceptual experience of frequency. The change in frequency that occurs when a train passes a crossing or an ambulance passes on the street is due to the Doppler effect. If you are standing at a railroad crossing for example, the frequency of an approaching train falls slightly as the train approaches, falls rapidly as the train passes, and then continues to fall at a slower rate as the train fades into the distance. Despite this fact of physics, most people tend to hear a pitch rise as the train approaches and a pitch fall as the train departs.

We tested this phenomenon in the laboratory by presenting listeners with simulated Doppler shifted tones and asking them to track with a joystick the changes in pitch that they heard. Listeners moved the joystick forward as they heard pitch rise and backward as they heard pitch fall. We found that despite the fact that frequency falls, most listeners hear a rise in pitch as the sound source approaches. Since the physical measurement of frequency and the perceptual experience of frequency (i.e. pitch) were going in opposite directions, we called this phenomenon the Doppler illusion. The pattern of pitch change that is heard (rising then falling) resembles the pattern of loudness change that occurs. We argue then that the Doppler illusion is due to the change in loudness that occurs as the train approaches. More generally, dynamic changes in loudness can influence perceived pitch in a previously undocumented way.

As a sound source approaches a listener it grows louder. Our laboratory task required that listeners attend to the change in pitch and to ignore the change in loudness. If listeners are asked to attend only to the change in pitch that occurs and ignore the loudness change, they almost always fail. Their judgments are influenced by the change in loudness. These results suggest that under dynamic conditions, the perception of pitch and loudness interact. Specifically, dynamic increases in loudness, like those that occur when a train approaches, can lead to the perception of rising pitch. The effect is noteworthy because as the train approaches, frequency, which is the primary determinant of pitch, actually falls.

To further explore the dynamic pitch-loudness interaction we presented listeners with tones that had different combinations of changing pitch and loudness. This was to see if loudness change influences perceived pitch in situations that are not specified by a Doppler shift. Loudness would rise, fall or remain constant, while pitch either rose, fell or remained constant. In the first experiment we asked listeners to attend to changes in pitch. We found that in all of the cases dynamic intensity change influenced perceived pitch.

In a second experiment we presented listeners with the same types of tones but asked them to track changes in loudness. We wanted to see if dynamic frequency change would influence loudness change in the same way that dynamic intensity change influenced perceived pitch. We found a similar pattern of results. That is, dynamic changes in frequency influenced perceived loudness. The results suggest that under conditions of dynamic change, the perception of pitch and loudness interact. This dynamic interaction is qualitatively different from any interaction that occurs under similar static conditions (where static tones change in pitch or loudness from trial to trial). While there is certainly much more work to be done on the topic, the current findings regarding dynamic interaction may have implications for improving emergency vehicle warnings, auditory virtual reality, and perhaps even contributing to our understanding of speech perception.

Journal of Experimental Psychology: Copyright 1996 by the American Psychological Association, Inc.
Human Perception and Performance 0096-1523/96/$3.00 1996, Vol. 22, No. 4, 970-985

The Doppler Illusion:
The Influence of Dynamic Intensity Change on Perceived Pitch John G. Neuhoff and Michael K. McBeath Kent State University Four studies illustrate a new auditory illusion associated with the Doppler effect and demonstrate a new influence of dynamic intensity change on perceived pitch. Experiment 1 confirmed the existence of a popular belief that the pitch of a moving sound source rises as the source approaches. Because there is no corresponding rise in frequency, the authors refer to the perceived pitch rise as the Doppler illusion. Experiment 2 confirmed that the effect occurs perceptually, so the belief in a "naive principle" of physics has a perceptual basis. Experiment 3 confirmed the effect does not occur under matched static conditions. Experiment 4 showed that the influence of dynamic intensity change on perceived pitch occurs outside the realm of Doppler stimuli. The findings support a dynamic dimensional interaction of pitch and loudness, with marked differences in the perception of pitch and loudness under static and dynamic conditions.