  Piezoelectric micromachined ultrasound transducers (PMUTs) have gained
popularity in the past decade as acoustic transmitters and receivers. As these
devices usually operate at resonance, they can deliver large output sound
pressures with very low power consumption. This paper explores the influence of
the transmitter's packaging on the radiated acoustic field in air. We run
simplified axisymmetric numerical models to observe the change in the acoustic
field and directivity with respect to the device's package dimensions. The
simulations demonstrate a notable change in the directivity of transmitter
based on the size of the baffle. Experimental measurements are carried out to
validate the simulations, which prove useful in designing packages for
transmitters to meet application specific requirements.
