According to a Guardian article, we’ve been listening to the legendary bluesman Robert Johnson at the wrong speed all these years.
The story claims that his music has been reproduced at the wrong speed for decades:
Either the recordings were accidentally speeded up when first committed to 78, or else they were deliberately speeded up to make them sound more exciting. Whatever, the common consensus among musicologists is that we’ve been listening to Johnson at least 20% too fast.
Jon Wilde, who wrote the article says that the findings are based the examination of Johnson’s guitar tunings on the recordings so Johnson would sound more like this: