I'm going to try this tonight with a c-cell and an old Subaru speaker in the basement. I'll let you know. I'm with the pop-on-contact-no-sound-otherwise camp.

However, one way in which this may make sense: a battery is a dc device, however the chemistry can only convert electrons so quickly. A speaker is essentially a short circuit to DC power, meaning that the DC voltage would drop quickly, perhaps there would be variations in voltage/amperage which cause the speaker cone to vibrate about a DC biased position, making noise.

-Zeke