Talk:Just-noticeable difference

Scheme

We are looking for a scheme of the JND of Weber-Fechner. The explanation are very weel but a scheme will help all students or people to understand better, i think!

I think this is a British English-American English problem for me, but what exactly do you mean by "the scheme of the JND of Weber-Fechner? SJS1971 12:54, 5 February 2007 (UTC)

I think he wants an example.--Filll 12:59, 5 February 2007 (UTC)

How about this for an example and reference on JND? http://webphysics.davidson.edu/faculty/dmb/soundRM/jnd/jnd.html - Cheers Mark Vincent Andmark (talk) 13:16, 11 March 2008 (UTC)

Problematic reference

I think there is a problem with one of the references:

Booth, D.A., & Freeman, R.P.J. (1973). Discriminative measurement of feature integration. Acta Psychologica (Amsterdam).

I couldn't find this paper but I found this one: http://dx.doi.org/10.1016/0001-6918(93)90068-3 -Hadarl (talk) 20:42, 14 May 2011 (UTC)

I don't know what to call this either

I was messing with a tone generator and this happened. I played 660 Hz. I heard an E. I played 659.255113826 Hz. I heard another E. I played them together. I got a headache. Why did this happen? 32ieww (talk) 00:39, 19 July 2016 (UTC)

Your headache is likely psychosomatic from the interference wave. When two sounds are played together, we hear the two frequencies as well as their difference. So in this case you heard 660Hz and 659.25Hz (I doubt your computer's hardware is more accurate than that), as well as .75Hz, which would have sounded like the volume coming in and out .75 times a second (or 3 times every 4 seconds). Perhaps the swaying volume reminded you of physical discomfort or nausea and your brain sent you a signal (pain) to abort the mission. The mechanisms of noise-related headache triggers don't seem to be very well understood in modern psychology.

2607:FEA8:D160:22B:752C:FE89:D680:D90A (talk) 14:46, 20 November 2019 (UTC)

Combination tones. Hyacinth (talk) 08:10, 28 November 2019 (UTC)

This page has significant problems - the definition of JND is incorrect

Unfortunately this page is confusing the concept of a difference threshold (a physical quantity, related to the Weber fraction) and the just noticeable difference (a psychological quantity). The goal of psychophysics is to relate physical parameters to subjective experiences. The difference threshold is a physical parameter but the JND describes a subjective experience.

The definition given at the top of the page is a reasonable definition of a difference threshold. However, the JND describes the subjective experience that accompanies the ability to discriminate two intensities. As Weber's Law makes clear, the difference threshold might be small when comparing small quantities (I can easily tell the difference in a bag holding 1 coin vs. a bag holding 2), but large when comparing large quantities (I can't tell a bag holding 100 coins from one holding 101, but I can tell a bag holding 100 from one holding 200). Thus, the difference threshold changes as the comparison quantities change. The JND does not. The JND is the subjective experience of a difference. 1 and 2 coins are separated by 1 coin (the difference threshold) and 1 JND (I can just tell the difference); 100 and 200 coins are separated by 100 coins (the difference threshold) but just 1 JND (if I can't tell 100 from 199 but can just tell the difference at 100 vs. 200).

What really needs to change is the title of this page, which is all about difference thresholds not JNDs. SJS1971 (talk) 15:40, 24 January 2018 (UTC)

@SJS1971: The difference between 100 and 200 coins is a "difference" of 100; the "resultant" of subtracting 100 from 200. I can only guess, but by "difference threshold" you may be referring to absolute threshold or sensory threshold.

To quote one of the sources: "For example: Suppose that you presented two spots of light each with an intensity of 100 units to an observer. Then you asked the observer to increase the intensity of one of the spots until it was just noticeably brighter than the other. If the brightness needed to yield the just noticeable difference was 110 then the observer's difference threshold would be 10 units (i.e., delta I =110 - 100 = 10)." 110-100=10, NOT 110-109=1. Note that ratios are used: "The Weber fraction equivalent for this difference threshold would be 0.1 (delta I/I = 10/100 = 0.1)." Hyacinth (talk) 08:10, 28 November 2019 (UTC)

Adding to this, in the music section: "Below 500 Hz, the JND is about 3 Hz for sine waves, and 1 Hz for complex tones" does not seem correct without a lower bound for this range. Since pitch is logarithmic, a 3Hz difference in one octave is exponentially different from a 3Hz difference in another. For example, a 1Hz sine wave beeps once per second, and a 4Hz sine wave beeps four times per second, which is definitely noticeable. As well, the lowest octave on a grand piano (27.5-55Hz) has frequency intervals of only 1-2Hz, and so this statement implies that we can't really discern between the lowest notes on a grand piano. From playing around with a tone generator I would hazard a guess the lower bound would be between 100-200, but that is hardly scientific. Perhaps "below" could be changed to "just below" 2607:FEA8:D160:22B:752C:FE89:D680:D90A (talk) 15:00, 20 November 2019 (UTC)

A sine wave is continuous both in motion and pitch. You may be thinking of a pulse wave or you may have meant something beside, "beeps," such as, "recurs"/"reoccurs". Hyacinth (talk) 08:10, 28 November 2019 (UTC)