The SoundCompass is able to discriminate a sound source within a half-quadrant (45°) with a frequency of 1,630 Hz or higher. Scaling down the size of the SoundCompass, by removing the outer rings, has a negative impact on the array directivity over all frequencies. (a) The SoundCompass polar directivity, Dp, increases with frequency; it surpasses eight after 1,630 Hz. Removing the SoundCompass’ outer rings (see Figure 5) reduces the array aperture and the number of microphones, but also reduces the directivity, Dp. (b) The polar directivity, Dp, can be interpreted as the ratio of the area of the unit circle over the area of the P-SRP (gray area). A P-SRP with Dp = 8 has the same area as a 45° sector and is therefore able to pinpoint a direction within a half quadrant.