Acoustic display system and method for ultrasonic imaging

DETAILED DESCRIPTION The invention provides an ultrasonic imaging system with a three-dimensional acoustic display.
In the preferred embodiment, this is accomplished by scanning an interrogation volume of a patient's body with a transducer at a plurality of scanned sample volumes.
A beamformer then forms a beam of returned signals from each respective scanned sample volume for each of a predetermined number of independent velocity directions.
Channel separation and projection circuits then convert each beam into a plurality of channel signals; alternatively, the channel separation and projection circuits can operate on previous scan data stored in a conventional cine memory.
A filter coefficient processor then selects, for each channel signal, one of a plurality of predetermined head-related transfer function (HRTF) parameter sets according to a predetermined function of the position in the interrogation region of the corresponding scanned sample volume and of the respective independent velocity direction.
Each HRTF parameter set defines left-ear and right-ear response functions to a calibration sound generated at a calibration point in a calibration space; the calibration point itself corresponds to a predetermined position in the interrogation volume.
An HRTF filter then filters each channel signal as a predetermined function of the corresponding HRTF parameter set.
The HRTF-filtered channel signals are then combined into left and right audio output signals.
A speaker system combines the audio output signals into audio display signals, which are used to drive first and second speakers.
The user thereby hears the combined audio display signals as if they were coming from non-colinear points of origin.
In a calibration mode, a pair of head-related transfer functions (HRTF) is determined for each of a plurality of calibration points in a predetermined calibration space.
The HRTF's in each pair correspond to left-ear and right-ear response functions to a calibration sound generated at the respective calibration points