The Haskins Laboratories' Pulse Code Modulation (PCM) System

The Pulse Code Modulation (PCM) method of digitizing analog signals has become a stan~ard both in digital audio and in speech research, the focus of this paper. The solutions to some problems encountered in earlier systems at Haskins Laboratories are outlined, along with general properties of AID conversion. Specialized features of the current Haskins Laboratories system, which has also been installed at more than a dozen other la?oratories, are al~o detailed: the Nyquist filter response; the high frequency pre· emphasIs ?lter charactenstics; the dynamic range; the timing resolution, for single and ~synchro~llzed)dual channel signals; and the form of the digitized speech files (header mformation, data, and label structure). While the solutions adopted in this system are not intended to be considered a standard, the design principles involved are of interest to users and creators of other PCM systems.