IEEE Std 269 pdf free download

IEEE Std 269 pdf free download.Measuring Electroacoustic Performance of Communication Devices.
For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dictionary Online should be consulted for terms not defined in this clause.’6
A-weighted: A measurement made using the “A” frequency weighting specified in ANSI S 1.4-1983. It approximates the frequency response of the ear at 40 dBSPL, so it is frequently used for measurements at low sound levels. For completely different reasons, it is also used for many acoustic safety measurements. It is generally not appropriate for use at typical terminal conversation levels.
acoustic echo canceller (AEC): A circuit or algorithm designed to eliminate acoustic echoes and prevent acoustic feedback from loudspeaker to microphone.
acoustic echo path: The acoustic coupling from the handset or headset receiver to the handset or headset microphone.
acoustic input: The free field sound pressure level developed by a mouth simulator at the mouth reference point. See: sound pressure level.
acoustic output: The sound pressure level developed in an ear simulator or at the measuring microphone. See: sound pressure level.
active level: Level of a signal with pauses andlor silences removed. Active level (decibels) is equivalent to the level of the original signal plus 10 x log( 100 / A). “A” is the nonspeech activity factor in percent.
active spectrum: Spectrum of a signal with pauses andlor silences removed. The active spectrum (decibels) is equivalent to the spectrum of the original signal plus 10 x log( 100 / A). “A” is the nonspeech activity factor in percent.
active speech level (ASL): Speech level measured according to Method B of ITU-T Recommendation P.56, which accounts for pauses or silences. The method involves the use of smoothing, hangover time, and thresholds. ASL (decibels) is equivalent to the level of the entire signal, including pauses andlor silences, plus lOx log(l00/A). “A” is the speech activity factor in percent.
active speech spectrum: Speech spectrum that accounts for pauses or silences. The active speech spectrum (dB) is equivalent to the spectrum of the entire signal, including pauses andlor silences, plus lOx log(100/A). “A” is the speech activity factor in percent.
activity factor (nonspeech): Percentage of time during which a nonspeech signal is present, excluding pauses or silence.
activity factor (speech): Percentage of time during which speech is present, as measured according to Method B of ITU-T Recommendation P.56.
analog subs steni: A device that connects to a two-way voice communication terminal in analog format, regardless of internal architecture. Analog handsets and headsets are examples.
codec: A combination of an analog-to-digital encoder and a digital-to-analog decoder operating in opposite directions of transmission within the same equipment. conditioning: The application of a signal prior to the measurement to place the device in an active and stable state. Speech is typically used as a conditioning signal. constant percentage bandwidth (CPB) analysis: A measurement in fractional octaves, typically implemented as a digital filter bank, without time gaps, suitable for computing the spectrum of stationary or nonstationary signals. Fulfills ANSI S1.11/IEC 61260-1 and ANSI S1.4/IEC 61672-1. Sometimes called “real time analysis.” NOTE- See Annex A for additional information. convergence time (Tc): The time required for echo to reach within 3 dB of maximum echo return loss, or 25 dB loss, whichever occurs first. conversational gain: The difference in level between a face-to-face conversation at 1 m and a conversation using a communication device.IEEE Std 269 pdf download.