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  2. Dictation machine - Wikipedia

    en.wikipedia.org/wiki/Dictation_machine

    In the 1990s, improvements in voice recognition technology began to allow computers to transcribe recorded audio dictation into text form, a task that previously required human secretaries or transcribers. The files generated with digital recorders vary in size, depending on the manufacturer and the format the user chooses.

  3. Sound recording and reproduction - Wikipedia

    en.wikipedia.org/wiki/Sound_recording_and...

    [citation needed] Similar designs appeared in barrel organs (15th century), musical clocks (1598), barrel pianos (1805), and music boxes (c. 1800). A music box is an automatic musical instrument that produces sounds by the use of a set of pins placed on a revolving cylinder or disc so as to pluck the tuned teeth (or lamellae ) of a steel comb.

  4. List of measuring instruments - Wikipedia

    en.wikipedia.org/wiki/List_of_measuring_instruments

    A pair of scales: An instrument for measuring mass in a force field by balancing forces. Balance; Check weigher measures precise weight of items in a conveyor line, rejecting underweight or overweight objects. Inertial balance; Katharometer; Mass spectrometers measure the mass-to-charge ratio, not the mass, of ionised particles. Weighing scale

  5. Sonar - Wikipedia

    en.wikipedia.org/wiki/Sonar

    To measure the distance to an object, the time from transmission of a pulse to reception is measured and converted into a range using the known speed of sound. [28] To measure the bearing , several hydrophones are used, and the set measures the relative arrival time to each, or with an array of hydrophones, by measuring the relative amplitude ...

  6. Spectrum analyzer - Wikipedia

    en.wikipedia.org/wiki/Spectrum_analyzer

    Spectrum analyzers are widely used to measure the frequency response, noise and distortion characteristics of all kinds of radio-frequency (RF) circuitry, by comparing the input and output spectra. For example, in RF mixers, spectrum analyzer is used to find the levels of third order inter-modulation products and conversion loss.

  7. Tape recorder - Wikipedia

    en.wikipedia.org/wiki/Tape_recorder

    A reel-to-reel tape recorder from Akai, c. 1978. An audio tape recorder, also known as a tape deck, tape player or tape machine or simply a tape recorder, is a sound recording and reproduction device that records and plays back sounds usually using magnetic tape for storage.

  8. Acoustic metamaterial - Wikipedia

    en.wikipedia.org/wiki/Acoustic_metamaterial

    The bulk modulus β is a measure of a substance's resistance to uniform compression. It is defined as the ratio of pressure increase needed to cause a given relative decrease in volume. The mass density (or just "density") of a material is defined as mass per unit volume and is expressed in grams per cubic centimeter (g/cm 3). [13]

  9. Speed of sound - Wikipedia

    en.wikipedia.org/wiki/Speed_of_sound

    The speed of sound for pressure waves in stiff materials such as metals is sometimes given for "long rods" of the material in question, in which the speed is easier to measure. In rods where their diameter is shorter than a wavelength, the speed of pure pressure waves may be simplified and is given by: [ 11 ] : 70 c s o l i d = E ρ ...