2.2. 1946-1975

• 1946: the SMPE sponsored, and the ASA approved, standards Z22.51, "Intermodulation Tests on VariableDensity 16-mm Sound Motion Picture Prints".
  
• 1946: the SMPE sponsored, and the ASA approved, Z22.52, "Cross-Modulation Tests, 16-mm VariableArea Photographic Sound".
  
• 1948: practices for audio transmission were standardized in the Radio, Electronics, and Television Manufacturers' Association (RETMA) Standards TR-105A, "Audio Facilities for Radio Broadcasting".
  
• 1949: the RETMA produces the standard SE-101A, "Amplifiers for Sound Equipment".
  
• 1949: the RETMA adopted a group of audio standards on microphones, amplifiers, and loudspeakers for sound equipment; there was also a "Standard Frequency Test Record," REC-128, and "Phonograph Pickups," REC-125A.
  
• 1950-1955: the IRE Sound Recording and Reproducing Committee produced the standards outlined by the ASA/SMPE committee in its 1948 report: flutter, noise, and frequency response. The IRE "Standards on Audio Techniques" were:
  
• 1951: 51 IRE 6.S1, "Definitions of Terms" (later designated IEEE Std 151);
  
• 1953: 53 IRE 19.S1, "Standards on Sound Recording and Reproducing: Methods of Determining Flutter Content" (later designated IEEE Std 193, and ANSI Z57.1);
  
• 1953: 53 IRE 19.S1, "Methods of Measuring Noise" (later designated as IEEE Std 191);
  
• 1954: 54 IRE 3.S1, "Definitions of Terms".
  
• 1953: the NARTB published the first USA magnetic tape recording standard.
  
• 1954: the AES published its only standard to date, TSA-1-1954, "Standard Playback Characteristic for Lateral Disk Recording"; the same characteristic was adopted that year by the RIAA as "Standard Recording and Reproducing Characteristic", Bulletin N. E1.
  
• 1956: a survey on the status of audio engineering standards was published in the IRE Transactions on Audio; it lists 32 standards.
  
• 1956: the IRE Sound Recording and Reproducing Committee produced the 56 IRE 3.S1, "Methods of Measurement of Gain, Amplification, Attenuation, Loss, and Amplitude-Frequency Response" (later designated IEEE Std 150, and ANSI C16.29).
  
• 1958: the IRE adopted 58 IRE 19.S1, "Methods of Calibration of Mechanically-Recorded Lateral Frequency Records" (later designated IEEE Std 192, and ANSI S4.1-1960).
  
• 1964: the NAB revised their "Disk Recording and Reproducing" standard;
  
• 1965: the NAB revised their magnetic tape recording standards, introducing a standard for tape cartridges for radio broadcasting.
  
• 1960-1965: the EIA approved many new audio standards, and revised many of their older audio standards.
  
• 1960-1965: the RIAA issued several disk and tape recording standards.
• 1971: measurement standards include a revision of the "Flutter measurement standard" (IEEE Std 193-1971, also ANSI S4.3-1972).
  
• 1972: measurement standards include a "Magnetic Tape Flux measurement standard" (IEEE Std 347-1972, also ANSI S4.6).
  
• 1970-1975: the EIA adopted, and the ANSI approved, standards on tape records on 6.3-mm tape on open reels, and on cassette tapes.

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