Valentin Chapero is telling Wall Street that Sonova, led by its Phonak brand of hearing aids, will still vie to become the world’s number one hearing-aid company even after the collapse of its bid to acquire GN Resound from GN Store Nord. The German trade authorities blocked the bid with a final decision this past week forbidding the merger in Germany, where the combination would create an effective oligopoly with three companies in control of 90 percent of the hearing-aid market. Sonova CEO Chapero has told analysts he still expects Phonak to grow faster than the rest of the industry and close in on Siemens Hearing and the William Demant companies, the world’s two biggest hearing-aid companies. GN Store Nord, which has a highly successful head-set business, now has to decide whether to seek another buyer for GN Resound, spin it out as a separate company, or hang onto it.