cross correlation
7.29 cross correlation; interaural cross correlation. Covariance of signals vs. time shift; i.e., the degree of similarity of a reference signal and a time-shifted signal, as a function of time shift or delay. Annotation 1 The cross correlation is calculated as where T is the observation period, and a(t) and b(t) are the respective signals. Annotation 2 The coefficient of correlation varies from +1 (perfectly correlated; i.e., the two signals are identical), through zero (completely uncorrelated; i.e., the two signals are completely independent or orthogonal), to –1 (perfectly correlated, but with a complete 180° phase inversion between the signals). Annotation 3 Auto correlation is the degree of similarity of a […]
mechanical coupler
7.28 mechanical coupler. Device that presents a specified mechanical impedance to a vibrator applied with a specified static force and equipped with an electromechanical transducer to measure the alternating force level at the surface of contact between vibrator and mechanical coupler. Annotation A mechanical coupler is specified in ANSI/ASA S3.13.
insertion gain
7.27 insertion gain. Difference between the earphone-presented sound pressure level and the open-ear sound pressure level, both measured at the eardrum. Unit, decibel (dB). Annotation Insertion gain may be measured with a probe microphone on a human listener or using a manikin equipped with an ear simulator.
simulated in situ
7.26 simulated in situ. Hearing aid measurements made on a manikin which represents the head, torso, pinna, ear canal, and eardrum of a median human adult, instead of an actual human subject. Annotation Descriptions of various applicable terms and simulated in situ measurements are provided in ANSI/ASA S3.35.
in situ
7.25 in situ. In the assessment of the performance of hearing aids, refers to measurements made on the hearing aid while it is in the position of normal use, i.e., on the ear of the wearer. Annotation Derived from the Latin words meaning “in position.”