Over the past 18 months, the mergers and acquisitions chief at Apple has been scouring the globe looking for deals, snatching up everything from search engines and data analytics to mapping software and motion tracking chips. [...] a buying spree has ignited fierce speculation in tech circles and on Wall Street about Apple's future ambitions, especially as smartphone and tablet sales start to slow. Led by Tomlinson Holman, a renowned audio engineer who invented THX and 10.2 surround sound, Apple is exploring ways to predict heart attacks by studying the sound blood makes at it flows through arteries. Taken together, Apple's potential forays into automobiles and medical devices, two industries worlds away from consumer electronics, underscore the company's deep desire to move away from iPhones and iPads and take big risks. [...] Apple's moves of late suggest a bit more urgency. Since the company hired Perica from Goldman Sachs in 2009, Apple has quickened its pace of acquisitions. At home and overseas, Apple faces strong competition from Android-based mobile devices. [...] most of Wall Street's attention has focused on Apple's long rumored iWatch device. In October 2013, German investment banking analyst Adnaan Ahmad created a media stir when he wrote an "open letter" to Apple CEO Tim Cook and board director Al Gore, urging the company to acquire Tesla. According to one document filed with the U.S. Patent and Trademark Office, the company is developing technology that could possibly unlock a device like an iPhone by identifying the owner's unique electrical signals from the heart.