The degree of latency is determined by the transmitter. Paired Bluetooth devices can only communicate by using the same audio CODEC. If your transmitter* does not support the aptX-LL low-latency Bluetooth audio CODEC, even though your BeHear headset does, you may sense a delay in the audio delivery.
aptX-LL provides the best performance with minimal latency. It is the recommended setting, and the BeHear default. aptX is similar to aptX-LL but the latency is slightly longer. SBC is the standard Bluetooth CODEC supported by all devices, latency is long and not fixed.
* The HearLink PLUS transmitter does support the aptX-LL low-latency audio CODEC, so you will not detect any audio delay when using it with your BeHear headset.