The TR-89B Transducers can be manufactured under special order
to resonate at any specified frequency between 23kHz and 40kHz.
Massa stocks two standard versions. The TR-89B Type 23 provides peak
untuned receiving response at 23kHz +/-2kHz, and the TR-89B Type 40
provides peak untuned receiving response at 40kHz +/-2kHz. The beam
patterns of the transducers change at different frequencies, and greater
detection range is obtained with lower frequency transducers due to
the attenuation characteristics of sound in air. Thus, the TR-89B Family
offers the user a choice of transducers that have characteristics that will
meet most requirements. Special frequencies, matched transmitting
and receiving pairs, and other custom features are available on special
order (consult factory). There are several million TR-89B Transducers in
use in many different applications throughout the world.