Abstract: A measurement system includes a number of audio transducers configured in a first arrangement for acoustic testing of a subject in a testing position, one or more sensors for collecting measurement data characterizing a position of a subject's head relative to the audio transducers, a controller for processing the measurement data to determine feedback data characterizing a difference between the position of the subject's head and the testing position, and a feedback indicator for presenting the feedback data to the subject.

Abstract: An immersive hearing loss and auditory prostheses simulator allows a person who listens through the simulation system to experience an actual shift in his or her thresholds for detecting ambient sounds, in a way that is similar to the shift in thresholds experienced by a hearing-impaired person. The simulator shifts the listener's thresholds while also processing the input signals for suprathreshold stimulation. With a controlled degree of auditory threshold shift with loudness recruitment, a hearing loss simulator is made valid and flexible.

Abstract: A hearing aid has a directional receiving system with a more efficient direction into the patient's ear than away from the patient's ear.

Abstract: A hearing aid has a plurality of microphones mounted in an array on a headband which extends from one ear over the top of the head to the other ear. The headband is flexible and adjustable in length. The headband has circuitry that can be switched among a directional monaural mode, a binaural mode, and a combination mode that provides both directionality and binaurally. Ganged controls are provided on the headband for both tone and volume. An external jack is provided on the headband to allow for the introduction of radio or recorded music from a personal stereo.

Abstract: Multiple single-frequency tones are presented simultaneously to a subject by each of two transducers for the purpose of testing hearing. One transducer is employed to present a plurality of f.sub.1 primaries and the other transducer a plurality of f.sub.2 primaries so as to make the ratio of f.sub.2 to f.sub.1 sufficient to produce evoked distortion products by the pair. Proper selection of the frequencies prevents numerous intermodulation products.

Abstract: Multiple single-frequency tones are presented simultaneously to a subject by each of two transducers for the purpose of testing hearing. One transducer is employed to present a plurality of f.sub.1 primaries and the other transducer a plurality of f.sub.2 primaries so as to make the ratio of f.sub.2 to f.sub.1 sufficient to produce evoked distortion products by the pair. Proper selection of the frequencies prevents numerous intermodulation products.

Abstract: The invention provides an adaptive noise cancelling apparatus which operates to overcome a problem encountered in conventional noise cancelling circuitry when the signal-to-noise ratio at the sensor array is high--to wit, that the target signal is degraded, leading to poorer intelligibility. An apparatus constructed in accord with the invention selectively inhibits the adaptive filter from changing its filter values in these instances and, thereby, prevents it from generating a noise-approximating signal that will degrade the target component of the output signal.