The chief financial officer of Sony Corp., Kevin Kelleher, has raised questions over the impact of free streaming tiers on paid for music subscriptions services.

Speaking to investors, Kelleher said that the Sony Music parent is “very encouraged” by the growth of premium subscription services, prediction that the model will make up 60% of music industry revenue in four years time.

However, Kelleher had questions about the impact free, ad-supported tiers are having on the growth of their paid for ...