Talk:Interval class

source for formula definitions: Basic Atonal Theory by John Rahn.

Error

"For example, the interval class between pitch classes 4 and 9 is 5 because 9 - 4 = 5 is smaller than 4 - 9 = -3 ≡ 7. See modular arithmetic for more on modulo 12."

IMHO, 4 - 9 = -3 ≡ 9 (modulo 12), because -3 + 12 = 9. At least I hope I understand the article correctly (I am not completely sure, that's why I will not edit the article). -- Viliam Bur 195.46.70.44 13:17, 3 February 2006 (UTC)

Oops!

Thank you for bringing that error to my attention! I'm not sure how I arrived at 4-9=-3, but the answer, of course, is 4-9=-5, which is equivalent in mod 12 to 7. Sorry about that. And yes, -3 does equal 9 in mod 12. Thanks again for noting that oversight. Psfitzgibbon 03:45, 4 February 2006 (UTC)

Problems

Contrary to what is said in this article, the notion of "interval class" can also defined in pitch space. (The interval class between C4 and E4 is 4, just as the interval class between E4 and C4 is 4.) Consequently, the contrast with tonality terminology is weak -- what is being contrasted here are pitch intervals in tonal theory with pitch class intervals in chromatic theory. Tymoczko 17:05, 23 February 2006 (UTC)

This article, as I see it, is not intended for people like you who already understand interval class -- it's for the uninitiated. Therefore, the point of the terminological comparisons is to give those who already understand basic tonal theory something to latch on to, as well as to illustrate the need for related but discrete post-tonal terminology.

Of course atonal terminology contains a correlate to tonal pitch interval: unordered pitch interval. But, as you know, interval class IS NOT the same thing as unordered pitch interval -- the former is defined only in pitch class space; the latter, only in pitch space.

Thank you for writing, though. If you wish to do so, I certainly encourage you to contribute again.

Best, Psfitzgibbon 00:25, 14 May 2006 (UTC)

Diatonic and chromatic

The article uses the terms "diatonic" and "chromatic" without adequate explanation. These terms are the cause of serious uncertainties at several Wikipedia articles, and in the broader literature. Specifically here, diatonic is not necessarily an adequate gloss on heptatonic, especially given the way things are classified at the article Heptatonic (to which I have just provided a link). And even if diatonic is intended at the present article, that excludes other heptatonic scales from treatment here. But that can't be right! Some of us thought that both terms needed special coverage, so we started up a new article: Diatonic and chromatic. Why not have a look, and join the discussion? Be ready to have comfortable assumptions challenged! – Noetica^♬♩ Talk 06:12, 6 April 2007 (UTC)

Use of interval class example

On the (3) in the Use of interval class example, isn't the interval from F# to Db a perfect fifth? Newsandpolitics —Preceding comment was added at 02:46, 28 June 2008 (UTC)

No. F# to Db isn't a perfect fifth. It's enharmonically equivalent to (it will sound the same as) a perfect fifth (Gb to Db, or F# to C#), but it's called a diminished sixth because of the note names that are used. In the tonal context, intervals are "numbered" (unison, second, third, fourth, fifth, etc.) by counting the note names (letters) included in the span, redardless of accidentals. Counting letters from F up to D results in six letter names (F, G, A, B, C, and D), so the interval is called some kind of sixth. The kind of sixth that it is depends on the real distance, which you can distinguish using semitones (half steps). A diminished sixth spans 7 semitones. So does a perfect fifth. Thus the easy confusion. --98.151.178.38 (talk) 05:09, 12 June 2012 (UTC)

citation removed

Please cite the exact paragraph not blatantly add a book name and assumed your interpretation of the context is correct. (WP:SYN) Interpretation between various people differs and wikipedia does require verification (WP:V) and detail evidence. (WP:REF- inline citation) --173.183.102.184 (talk) 23:25, 16 January 2010 (UTC)

For your information, it is not customary to cite paragraphs when giving a reference citation. The citation you removed included a specific page reference, which is more than sufficient. I have restored the citation. If you have inspected the pages cited and find they do not support the claim, then please tag it with {{Failed verification}} and bring your explanation to this Talk page. As far as I can see, the definition of "interval class" cited in Whitall does not involve any interpretation or synthesis, and constitutes the "detail evidence" you seek. Personally, I can think of a number of books I would rather see cited on this subject than Whitall, but it is perfectly adequate for the purpose.—Jerome Kohl (talk) 01:33, 17 January 2010 (UTC)

Example 3: shouldn't that be F-sharp [not F-flat] to D-flat? What's printed here is not a diminished sixth. Please correct. — Preceding unsigned comment added by 152.3.43.200 (talk) 06:48, 16 January 2013 (UTC)

Use of interval classes

There is a mistake with the graphic example in the "Use of interval classes" section. The text refers to the interval of a diminished sixth in example 3; however, the graphic depicts an interval from F♭ to D♭, which is a major sixth. The listening example clarifies that the graphic should depict a F♯ to D♭, a dyad that would share "intervallic color" with the rest of the intervals provided. --Whygreen44 (talk) 07:47, 2 October 2014 (UTC)

I remade the graphic, but I'm waiting to become an autoconfirmed user before I can upload it. --Whygreen44 (talk) 08:10, 2 October 2014 (UTC)

I see that this image was uploaded by User:Hyacinth. Perhaps he would like to make this correction himself?—Jerome Kohl (talk) 18:57, 2 October 2014 (UTC)