Frequency‐selective detection of acoustic sources in the upper atmosphere is shown to offer advantages over a broad‐band detector in improving signal‐to‐noise ratio. A model for an optimum frequency is developed using simplified assumptions: i.e., a source with a Fourier spectrum of uniform amplitude; attenuation by absorption during propagation; local turbulence as the noise source. An optimum frequency is found where the signal‐to‐noise ratio is maximum as a function of altitude. Experimental evidence confirms that a peak in the signal‐to‐noise ratio exits for acoustic sources in the upper atmosphere.