Acoustic wave transmission paths and speeds are affected by thermal gradients in the atmosphere and sound speed and transmission paths are dependent on frequency, air temperature gradients, and atmospheric pressure. If you're interested in acoustic telemetry across agriculture fields of the order of 100 yards, bowl antenna's like those used to broadcast sound effects of football and soccer games might work.  Sound intensities decay as ~10 log range in meters.  Sound rms pressure levels decay as ~20 log range in meters.  Lower frequency sound path distortion would be less affected than higher frequency.  What kind of telemetry data and range are you interested in? For an acoustic system I assume you'd want the telemetry frequencies to be out of the normal response of the human ear (say < 20 Hz or > 20kHz) to avoid the area noise pollution.