{"id":5,"date":"2010-11-07T21:00:11","date_gmt":"2010-11-08T05:00:11","guid":{"rendered":"http:\/\/www.earlevel.com\/blog\/?p=5"},"modified":"2019-11-18T23:36:39","modified_gmt":"2019-11-19T07:36:39","slug":"the-sound-of-dither","status":"publish","type":"post","link":"https:\/\/www.earlevel.com\/main\/2010\/11\/07\/the-sound-of-dither\/","title":{"rendered":"The sound of dither"},"content":{"rendered":"

Dithering is about spreading errors out, so that they aren\u2019t related to the sampled signal. A constant background hiss is easier to ignore than tones that change depending on signal frequencies and amplitude.<\/p>\n

Here\u2019s a fixed-frequency sine wave, truncated to seven bits:<\/p>\n

7-bit sine tone, no dither
\n\n

Here\u2019s the same signal dithered, truncated to seven bits:<\/p>\n

7-bit sine tone, dithered
\nhttp:\/\/www.earlevel.com\/main\/wp-content\/uploads\/2010\/11\/7bit_dithered.mp3<\/a><\/audio><\/p>\n

Notice the problems with the non-dithered example, especially in the tail as the signal fades out and fewer bits are used.<\/p>\n

Here\u2019s a swept sine wave, first simply truncated to seven bits:<\/p>\n

7-bit sine sweep, no dither
\nhttp:\/\/www.earlevel.com\/main\/wp-content\/uploads\/2010\/11\/7bit_sweep_no_dither.mp3<\/a><\/audio>
\nAnd again dithered:<\/p>\n

7-bit sine sweep, dithered
\nhttp:\/\/www.earlevel.com\/main\/wp-content\/uploads\/2010\/11\/7bit_sweep_dithered.mp3<\/a><\/audio>
\nNote the aliased frequencies in the non-dithered sweep, and how the tail sounds like a square wave as it fades out.<\/p>\n

In both cases, the dithered signal maintains the sine tone throughout, at the expensive of added \u201chiss\u201d.<\/p>\n

There are things we can do to make the hiss less obtrusive, but of course at the more normal 16-bit sample size, the dither-noise level is far lower than these extreme examples.<\/p>\n

Read the EarLevel article on dither<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Dithering is about spreading errors out, so that they aren\u2019t related to the sampled signal. A constant background hiss is easier to ignore than tones that change depending on signal frequencies and amplitude. Here\u2019s a fixed-frequency sine wave, truncated to … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[4,5],"tags":[],"_links":{"self":[{"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/posts\/5"}],"collection":[{"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/comments?post=5"}],"version-history":[{"count":2,"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/posts\/5\/revisions"}],"predecessor-version":[{"id":950,"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/posts\/5\/revisions\/950"}],"wp:attachment":[{"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/media?parent=5"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/categories?post=5"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.earlevel.com\/main\/wp-json\/wp\/v2\/tags?post=5"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}