An audio capture apparatus comprises a microphone array (301) and a beamformer (303) arranged to generate a beamformed audio output signal and a noise reference signal. A first and second transformer (309, 311) generates a first and second frequency domain signal from a frequency transform of the beamformed audio output signal and noise reference signal respectively. A difference processor (313) generates time frequency tile difference measures which for a given frequency is indicative of a difference between a monotonic function of a norm (magnitude) of a time frequency tile value of the first frequency domain signal and a monotonic function of a norm of a time frequency tile value of the second frequency domain signal for the first frequency. An estimator (315) generates an estimate indicative of whether the audio output signal comprises a point audio source in response to a combined difference value for time frequency tile difference measures for frequencies above a frequency threshold.