The stock price of the Australian company Cochlear has sunk after reporting slow sales of implants to China. The world’s biggest hearing implant company saw its shares fall more than 8% to just under $60. The price reached nearly $80 this past fall. Cochlear has a contract to supply more than 15,000 implants to China and Taiwan but fewer than 600 have been sold. Overall, revenue is up nearly 8% due to a 21% jump in sales of a device for less-severe hearing loss called the Baha.