NEW YORK — Sennheiser has opened two temporary pop-up stores in New York (shown here) and San Francisco, both of which will be open Nov. 22 through Dec. 28. The concept stores will serve as an urban hub, the audio manufacturer said, and will host events, offer refreshments to visitors, and premiere an interactive installation by artist Andreas Muller. They will also have a DJ booth and a gaming area where consumers can test products.