Interseptimal interval: Difference between revisions
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# Maj6-min7 -- intermediate between 12/7 and 7/4 -- 940¢-960¢ | # Maj6-min7 -- intermediate between 12/7 and 7/4 -- 940¢-960¢ | ||
Interseptimal intervals are well-represented in [[24edo]] at 250¢, 450¢, 750¢ and 950¢. As they fall in ambiguous zones between simpler categories, they are inevitably xenharmonic. | Interseptimal intervals are well-represented in [[24edo]] at 250¢, 450¢, 750¢ and 950¢. They also appear in [[19edo]] and [[29edo]]. | ||
As they fall in ambiguous zones between simpler categories, they are inevitably xenharmonic. This also makes them difficult to name: do we classify a 250-cent interval as a second, a third, both, or neither? One option is to give each region a distinct name (analogous to using the word //tritone// rather than diminished fifth or augmented fourth). Possible names that could be used are: | |||
# 240¢-260¢ -- semifourth -- an interval of this size is around half the size of a perfect fourth. | |||
# 440¢-468¢ -- semisixth -- an interval of this size is around half the size of a major sixth. | |||
# 732¢-760¢ -- semitenth -- an interval of this size is around half the size of a major tenth (i. e., compound major third). Another possible name is sesquifourth (since this is also about one and a half times the size of a perfect fourth). | |||
# 940¢-960¢ -- semitwelfth -- an interval of this size is around half the size of a perfect twelfth (i e., a compound perfect fifth, or tritave). All even [[edt|edts]] have a semitwelfth of approximately 951 cents, analogous to the 600 cent tritone shared by all even edos. | |||
This makes notating these intervals very easy as long as we have an agreed-upon symbol for "semi". | |||
By analogy the tritone could also be called a semioctave, although the term tritone is so well-established that seems is little reason to change it now. | |||
==Examples== | ==Examples== | ||
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<div style="width:100%; max-height:400pt; overflow:auto; background-color:#f8f9fa; border: 1px solid #eaecf0; padding:0em"><pre style="margin:0px;border:none;background:none;word-wrap:break-word;width:200%;white-space: pre-wrap ! important" class="old-revision-html"><html><head><title>Interseptimal</title></head><body>In the theory of <a class="wiki_link" href="/Margo%20Schulter">Margo Schulter</a>, <em>interseptimal</em> is a category of intervals which occupy regions intermediate between two septimal ratios such as <a class="wiki_link" href="/8_7">8/7</a> and <a class="wiki_link" href="/7_6">7/6</a>, or <a class="wiki_link" href="/12_7">12/7</a> and <a class="wiki_link" href="/7_4">7/4</a>. There are four interseptimal regions given below, with approximate cents ranges from Schulter's article <a class="wiki_link_ext" href="http://www.bestii.com/%7Emschulter/IntervalSpectrumRegions.txt" rel="nofollow">Regions of the Interval Spectrum</a>:<br /> | <div style="width:100%; max-height:400pt; overflow:auto; background-color:#f8f9fa; border: 1px solid #eaecf0; padding:0em"><pre style="margin:0px;border:none;background:none;word-wrap:break-word;width:200%;white-space: pre-wrap ! important" class="old-revision-html"><html><head><title>Interseptimal</title></head><body>In the theory of <a class="wiki_link" href="/Margo%20Schulter">Margo Schulter</a>, <em>interseptimal</em> is a category of intervals which occupy regions intermediate between two septimal ratios such as <a class="wiki_link" href="/8_7">8/7</a> and <a class="wiki_link" href="/7_6">7/6</a>, or <a class="wiki_link" href="/12_7">12/7</a> and <a class="wiki_link" href="/7_4">7/4</a>. There are four interseptimal regions given below, with approximate cents ranges from Schulter's article <a class="wiki_link_ext" href="http://www.bestii.com/%7Emschulter/IntervalSpectrumRegions.txt" rel="nofollow">Regions of the Interval Spectrum</a>:<br /> | ||
<ol><li>Maj2-min3 -- intermediate between 8/7 and 7/6 -- 240¢-260¢</li><li>Maj3-4 -- intermediate between <a class="wiki_link" href="/9_7">9/7</a> and <a class="wiki_link" href="/21_16">21/16</a> -- 440¢-468¢</li><li>5-min6 -- intermediate between <a class="wiki_link" href="/32_21">32/21</a> and <a class="wiki_link" href="/14_9">14/9</a> -- 732¢-760¢</li><li>Maj6-min7 -- intermediate between 12/7 and 7/4 -- 940¢-960¢</li></ol><br /> | <ol><li>Maj2-min3 -- intermediate between 8/7 and 7/6 -- 240¢-260¢</li><li>Maj3-4 -- intermediate between <a class="wiki_link" href="/9_7">9/7</a> and <a class="wiki_link" href="/21_16">21/16</a> -- 440¢-468¢</li><li>5-min6 -- intermediate between <a class="wiki_link" href="/32_21">32/21</a> and <a class="wiki_link" href="/14_9">14/9</a> -- 732¢-760¢</li><li>Maj6-min7 -- intermediate between 12/7 and 7/4 -- 940¢-960¢</li></ol><br /> | ||
Interseptimal intervals are well-represented in <a class="wiki_link" href="/24edo">24edo</a> at 250¢, 450¢, 750¢ and 950¢. As they fall in ambiguous zones between simpler categories, they are inevitably xenharmonic.<br /> | Interseptimal intervals are well-represented in <a class="wiki_link" href="/24edo">24edo</a> at 250¢, 450¢, 750¢ and 950¢. They also appear in <a class="wiki_link" href="/19edo">19edo</a> and <a class="wiki_link" href="/29edo">29edo</a>.<br /> | ||
<br /> | |||
As they fall in ambiguous zones between simpler categories, they are inevitably xenharmonic. This also makes them difficult to name: do we classify a 250-cent interval as a second, a third, both, or neither? One option is to give each region a distinct name (analogous to using the word <em>tritone</em> rather than diminished fifth or augmented fourth). Possible names that could be used are:<br /> | |||
<br /> | |||
<ol><li>240¢-260¢ -- semifourth -- an interval of this size is around half the size of a perfect fourth.</li><li>440¢-468¢ -- semisixth -- an interval of this size is around half the size of a major sixth.</li><li>732¢-760¢ -- semitenth -- an interval of this size is around half the size of a major tenth (i. e., compound major third). Another possible name is sesquifourth (since this is also about one and a half times the size of a perfect fourth).</li><li>940¢-960¢ -- semitwelfth -- an interval of this size is around half the size of a perfect twelfth (i e., a compound perfect fifth, or tritave). All even <a class="wiki_link" href="/edt">edts</a> have a semitwelfth of approximately 951 cents, analogous to the 600 cent tritone shared by all even edos.</li></ol><br /> | |||
This makes notating these intervals very easy as long as we have an agreed-upon symbol for &quot;semi&quot;.<br /> | |||
<br /> | |||
By analogy the tritone could also be called a semioctave, although the term tritone is so well-established that seems is little reason to change it now.<br /> | |||
<br /> | |||
<br /> | <br /> | ||
<!-- ws:start:WikiTextHeadingRule:0:&lt;h2&gt; --><h2 id="toc0"><a name="x-Examples"></a><!-- ws:end:WikiTextHeadingRule:0 -->Examples</h2> | <!-- ws:start:WikiTextHeadingRule:0:&lt;h2&gt; --><h2 id="toc0"><a name="x-Examples"></a><!-- ws:end:WikiTextHeadingRule:0 -->Examples</h2> | ||