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dictionary.com wrote:Usage Note: During the 15th century English experienced a widespread loss of certain consonant sounds within consonant clusters, as the (d) in handsome and handkerchief, the (p) in consumption and raspberry, and the (t) in chestnut and often. In this way the consonant clusters were simplified and made easier to articulate. With the rise of public education and literacy and, consequently, people's awareness of spelling in the 19th century, sounds that had become silent sometimes were restored, as is the case with the t in often, which is now frequently pronounced. In other similar words, such as soften and listen, the t generally remains silent.