A spokesman for the Save Zimbabwe Campaign says the loose coalition of opposition groups is determined to continue its "sounds of freedom" protests in which citizens are asked to make noise with horns, whistles or other means each Wednesday midday.
But organizers acknowledge that the protest has not drawn mass participation.
This Wednesday, observers in Harare, Mutare, Chinhoyi and Gweru reported no unusual noises, though a Bulawayo Save Zimbabwe Campaign coordinator said he had heard whistling, banging and hooting of horns in the city center.
The noise protest was launched in late 2006, but since the turn of the year opposition parties and groups have stepped up street marches and demonstrations.
Save Zimbabwe spokesman Jonah Gokovah told reporter Patience Rusere of VOA's Studio 7 for Zimbabwe earlier this week that his organization is still honing the strategy and considers it viable despite the emergence of more confrontational tactics.