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  2. Reference tone - Wikipedia

    en.wikipedia.org/wiki/Reference_tone

    In telecommunication, a standard test tone is a pure tone with a standardized level generally used for level alignment of single links and of links in tandem. [1]For standardized test signal levels and frequencies, see MIL-STD-188-100 for United States Department of Defense (DOD) use, and the Code of Federal Regulations Title 47, part 68 for other Government agencies.

  3. Tone decay test - Wikipedia

    en.wikipedia.org/wiki/Tone_decay_test

    A tone at the frequency of 4000 Hz is presented for 60 seconds at an intensity of 5 decibels above the patient's absolute threshold of hearing. If the patient stops hearing the tone before 60 seconds, the intensity level is increased by another 5 decibels with the procedure repeated until the tone can be heard for the full 60 seconds or until no decibel level can be found where the tone can be ...

  4. Audio system measurements - Wikipedia

    en.wikipedia.org/wiki/Audio_system_measurements

    A single 32-second sequence was standardized by the EBU in 1985, incorporating 13 tones (40 Hz–15 kHz at −12 dB) for frequency response measurement, two tones for distortion (1024 Hz/60 Hz at +9 dB) plus crosstalk and compander tests.

  5. Mains hum - Wikipedia

    en.wikipedia.org/wiki/Mains_hum

    Mains hum, electric hum, cycle hum, or power line hum is a sound associated with alternating current which is twice the frequency of the mains electricity.The fundamental frequency of this sound is usually double that of fundamental 50/60 Hz, i.e., 100/120 Hz, depending on the local power-line frequency.

  6. Equal-loudness contour - Wikipedia

    en.wikipedia.org/wiki/Equal-loudness_contour

    In their study, test subjects listened to pure tones at various frequencies and over 10 dB increments in stimulus intensity. For each frequency and intensity, the listener also listened to a reference tone at 1000 Hz. Fletcher and Munson adjusted the reference tone until the listener perceived that it had the same loudness as the test tone.

  7. Audio frequency - Wikipedia

    en.wikipedia.org/wiki/Audio_frequency

    The SI unit of frequency is the hertz (Hz). It is the property of sound that most determines pitch. [1] The generally accepted standard hearing range for humans is 20 to 20,000 Hz. [2] [3] [4] In air at atmospheric pressure, these represent sound waves with wavelengths of 17 metres (56 ft) to 1.7 centimetres (0.67 in).

  8. Loop around - Wikipedia

    en.wikipedia.org/wiki/Loop_around

    A loop line or loop around is a telephone company test circuit. The circuit has two associated phone numbers. When one side of the loop is called (side A), the caller receives a test tone of approximately 1000 Hz (milliwatt test). When the second number (side B) is called, it produces dead silence, but the party on side A hears the milliwatt ...

  9. Temporal envelope and fine structure - Wikipedia

    en.wikipedia.org/wiki/Temporal_envelope_and_fine...

    [182] [247] TFS-LF: this test assesses the ability to discriminate low-frequency pure tones that are identical at the two ears from the same tones differing in interaural phase. [248] [249] TFS AF: this test assesses the highest audio frequency of a pure tone up to which a change in interaural phase can be discriminated. [250]