**5.23 interaural phase****.** Phase (or time) difference between the signal and noise, or noise alone, parameter presented at one ear and the signal and noise, or noise alone, parameter presented at the other ear. Phase is usually referenced to one ear. Unit, radian.

Annotation 1 Typical signal (S) and noise (N) configurations are listed as follows:

N_{m}S_{m}: (monotic) – signal and noise to only one earphone.

N_{o}S_{m}: (mixed, dichotic) – signal to one ear; noise presented in-phase to both ears.

N* _{π}*S

_{m}: (mixed, dichotic) – signal to one ear; noise presented

*π*radians (180°) out-of-phase (noise is reversed in phase at one ear relative to the other ear).

N_{o}S_{o}: (homophasic, diotic) – signal and noise presented in-phase at both ears.

N* _{π}*S

*: (homophasic, dichotic) – signal and noise presented*

_{π}*π*radians out-of-phase (e.g., wires to one earphone reversed).

N* _{π}*S

_{o}: (antiphasic, dichotic) – signal in-phase to both ears; noise

*π*radians out-of-phase (noise reversed in phase at one ear).

N_{o}S* _{π}*: (antiphasic, dichotic) – signal

*π*radians out-of-phase (signal reversed in phase at one ear); noise in-phase at both ears.

N_{u}S_{o}: (heterophasic, dichotic) – signal in-phase to both ears; noise uncorrelated at the two ears (two independent noise sources).

N_{u}S* _{π}*: (heterophasic, dichotic) – signal

*π*radians out-of-phase (signal reversed in phase at one ear); noise uncorrelated at the two ears (two independent noise sources).

Annotation 2 The two ears are assumed identical and the ear selected as the reference is determined by keeping the phase difference between 0 and *π* radians, or the time difference positive.

Annotation 3 A fraction in terms of *π* radians appearing as the subscript in S_{( )} or N_{( )} where 0 ≤ ( ) ≤ *π*, indicates the interaural phase of signal or noise, e.g., N_{π/2}S_{π/2}.

Annotation 4 A decimal value for *u*, where –1.00 ≤ *u* ≤ +1.00, replacing the subscript *u* in the N_{u}S_{( )} , condition indicates the degree of interaural noise correlation, e.g., N + _{0.9}S_{m}. Note that the correlation always requires a sign and where phase is exactly equal to an integral number of radians, it should be expressed as *nπ*/*π*.

Annotation 5 An integer appearing as the subscript indicates the sound pressure level difference, in decibels, between signal and noise, or noise, at one ear relative the signal and noise, or noise, at the other ear, e.g., N_{2}S_{m}.

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