Retrospective transmit focusing using a transmit speed systems, devices, and methods

A method of retrospectively transmit focusing ultrasound data for ultrasound imaging, comprising:

• controlling, by a processor circuit, an array of acoustic elements in communication with the processor circuit to transmit ultrasound energy at a first transmit speed and receive echoes associated with the transmitted ultrasound energy;
• generating, by the processor circuit, a plurality of multilines based on the received echoes;
• determining, by the processor circuit, a second transmit speed;
• determining, by the processor circuit, a set of transmit focus delays based on the second transmit speed;
• adjusting, by the processor circuit, the plurality of multilines using the set of transmit focus delays;
• generating, by the processor circuit, an image based on the adjusted plurality of multilines;
• and
• outputting, by the processor circuit, the generated image to a display in communication with the processor circuit.