To this end, I've written a small python script, MeloSynth, to do just that:
MeloSynth is written in Python, is open source, and requires Python and NumPy. It's designed to be as simple as possible to use, no programming/python knowledge required. Given a txt or csv file with two columns [timestamps, frequency], the default behavior is to synthesize a wav file using a single sinusoid. The script also has options for setting the sampling frequency, adding more harmonics, changing the waveform, synthesizing negative values (which are used to indicate the absence of pitch by convention) and batch processing all files in a folder.
MeloSynth can of course also be used to synthesize pitch estimates from other algorithms, as long as the output is provided in the expected double column format.
Give it a spin and let me know what you think :)