SAN FRANCISCO - Apple Inc Chief Executive Tim Cook defended the company's record of innovation under his stewardship, saying he expected it would release "several more game changers" and hinting that wearable computers could be among them.

"It's an area where it's ripe for exploration," Cook said on Tuesday at the All Things Digital conference, an annual gathering of technology and media executives in the California coastal resort town of Rancho Palos Verdes.

"It's ripe for us all getting excited about. I think there will be tons of companies playing in this."

His remarks come at a time when worries are mounting that the company which created the smartphone and tablet market is ceding ground to competitors such as Samsung Electronics Co Ltd and Google Inc, with a slowdown in earnings growth hitting its share price.

Cook stopped short of clarifying if Apple was working on wearable products amid speculation that it is developing a smartwatch, saying only that wearable computers had to be compelling.

He added that Google's Glass - a cross between a mobile computer and eyeglasses that can both record video and access the Internet - is likely to have only limited appeal.

"There's nothing that's going to convince a kid who has never worn glasses or a band or a watch to wear one, or at least I haven't seen it," he said in the near one-and-a-half-hour question and answer session.

"So I think there are lots of things to solve in this space."

Cook also said he has a "grand vision" for television that goes beyond an existing $99 Apple TV streaming device, but did not go into details. The company has maintained for years that it harbors an interest in doing more in the TV arena.

Apple is not averse to doing a large acquisition if the acquired company could help Apple develop an important product, he said, noting it has done nine acquisitions in the current fiscal year, versus the company's historical average of about six deals a year.

Cook also hinted at updates to the company's iOS mobile software, saying the future of iOS would be evident when it holds its annual developer conference next month, and said the company was investing heavily in online services such as its mapping application.

Its Apple maps service that replaced a Google Maps app last September contained embarrassing errors, drawing fierce criticism from consumers and reviewers and forcing Cook to offer a public apology.

When asked if Apple has lost its cool, Cook said "absolutely not" and went on to list statistics of device sales and usage. He, however, acknowledged that he was frustrated with the sudden downturn in the firm's stock price.

Since hitting a record close of $702.10 last September, the world's largest technology company has shed 44 percent, losing more than $280 billion of market value - or more than the entire market capitalization of Google.

In April, Apple reported its first quarterly profit decline in over a decade and was also shunned by some well-known fund managers in the first quarter, with John Griffin's Blue Ridge Capital selling off its shares and Chase Coleman's Tiger Global Management sharply cutting their position.

Cook has tried to reset heightened expectations around the company and he has stressed that the company's position remains strong, noting it has opened up more of its treasure trove to investors, doubling its cash return program to $100 billion by the end of 2015.

Cook, who said that Apple's large size means it gets more scrutiny from governments and regulators, announced that the company has hired Lisa Jackson, who served as the Administrator of the US Environmental Protection Agency from 2009 to 2013.

Jackson will be reporting directly to Cook and overseeing Apple's environmental issues, he said.

The sense that Apple has lost some of its luster was evidenced when one member of the audience criticized the company for its apparent lack of exciting new technologies and compared Cook to Gil Amelio, a former Apple CEO who presided over a low point in Apple's history during the mid-1990s.

"We believe very much in the element of surprise," Cook responded. "We think customers love surprises."