A speaker module includes a casing and a speaker unit housed and fixed in the casing, a rear acoustic cavity being formed between the casing and the speaker unit, wherein at least one baffle wall is provided on the casing in the rear acoustic cavity and divides the rear acoustic cavity into at least two cavities, and wherein at least one slit is formed between the baffle walls or on the baffle wall, so that sound generated by the speaker unit can spread to an adjacent cavity inside the rear acoustic cavity through the slit.