jazz music in the style that began in New Orleans in the US in the early 20th century, rather than later styles of jazz that include a lot of improvisation (= a performance that a musician has not practised or planned)

It's a club where old-time musicians play traditional jazz. 那是一个旧式乐手演奏传统爵士乐的俱乐部。

Traditional jazz is largely instrumental music that combines the call-and-response rhythm of the fields during slavery in the American South. 传统爵士乐主要是器乐曲，结合了美国南方奴隶制时期田野对唱的节奏。