However, concerns over quality have not yet impacted sales of the handset, which the technology firm says grew 61% last quarter.
The brand’s “buzz”, a balance between the positive or negative things consumers have heard about the handset, sunk to 2.8 on Monday (18 July) from a quarterly high of 35.5 in May.
Apple’s handling of the situation has been questioned. It initially offered only an instruction to users to hold the device in certain way, a move that was considered a PR mistake.
The technology firm has since offered affected consumers a software update or a full refund. It has also looked to appease consumers with a free bumper case designed to improve the device’s performance.
Worryingly for Apple, the number of consumers willing to recommend the handset has also slumped. It stood at 13.7 on Monday, down from a quarterly high of 25.7 in May.
Despite perception problems, Apple says revenues in the three months to 26 June rose to $15.7bn (£10.3bn), helped by iPhone sales of 8.4 million.
Net profit was $3.25bn (£212bn), up from $1.83bn (£1.19bn) in the same period last year.
The news sent shares rising in the US. The company’s share price had taken a hit over speculation the device might have to be recalled.