Larry Page is the face of Google Inc., GOOG +1.09% but the chief executive has had trouble being its voice. On Tuesday, Mr. Page broke his silence as to why.

In a post on the company's Google+ social networking service, the 40-year-old CEO wrote that he had been diagnosed with a 'very rare' case of vocal-chord paralysis. After a bad cold 14 years ago, Mr. Page said that one of his vocal chords became paralyzed and his voice never fully recovered as doctors failed to find a cause.

Mr. Page added that his condition took a turn for the worse last year when another cold brought problems to his second vocal chord. Since then, however, his condition has improved, he said.

Today, Mr. Page said 'I'm fully able to do all I need to at home and at work, though my voice is softer than before.' He joked that fellow Google co-founder Sergey Brin 'says I'm probably a better CEO because I choose my words more carefully.'

The revelation caps what had been a mystery over Mr. Page's health. Mr. Page missed Google's annual shareholder meeting in June and other events after the Mountain View, Calif., company said he 'lost his voice,' though he continued to run the company. The lack of details surrounding the matter prompted speculation on Wall Street and elsewhere about whether Mr. Page may have had a serious medical condition.

Mr. Page subsequently told Google employees by email that there was 'nothing seriously wrong with me,' people familiar with the matter have said. Mr. Page's voice has continued to sound hoarse and raspy during earningsconference calls with investors.

Mr. Page's comments come one day before the start of Google's annualconference in San Francisco for software developers who create applications for Google's Android and Chrome computer-operating systems.

Corporate governance experts said Mr. Page's disclosure was a responsiblegesture to investors. Jeffrey Sonnenfeld, a seniorassociate dean at Yale School of Management, said Mr. Page's post stands 'in sharp contrast with [former Apple Inc. AAPL -2.39% CEO] Steve Jobs's denials and efforts to disguise the truth for a fair bit of time.'

Mr. Jobs died in 2011 at the age of 56 after suffering from pancreatic cancer. Apple's few disclosures about his health were criticized at times for providing minimal details about his condition.

People in such high-profile jobs at public companies have a 'responsibility to the public' to disclose their condition because they are so 'central to the strategic value of the business,' Mr. Sonnenfeld said.

In his post, Mr. Page offered more details on how his vocal chord paralysis has rippled out to other aspects of his health, including that his ability to exercise at 'peak aerobic capacity is somewhat reduced' because of the vocal chord's effect on his breathing.

He also said that his vocal chord issues have affected his thyroid gland and that he was diagnosed with Hashimoto's thyroiditis in 2003, though he added that it was 'a fairly common benign inflammatory condition of the thyroid which causes me no problems.'

Mr. Page added that he was funding a researchprogram at the Voice Health Institute that will be led by Steven Zeitels of Harvard Medical School.