When Tokyo Tsushin Kogyo was looking for a name that had been romanized (not in Japanese language or writing) to market their company, they considered strongly to use their abbreviation, TTK. The reason they didn't choose it was because there was a Tokyo Kyuko railway company which was then known as TKK.
The name "Sony" was chosen as a combination of Latin sonus, which is the root of sonic and sound, and the English word sonny (little boy) which after combined means a small group of young people who have the energy and strong will towards ideas that are not limited. At that time, it was very strange for a Japanese company to use Roman letters to spell his name, let alone the use of phonetic characters used in Japanese writing (rather than using Chinese characters). And in 1958 the company began formally adopting the name "Sony Corporation" as the company name. Easy to use and easy to spell in all languages of the world.