• Author / Uploaded
• Bulli Koteswararao

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An anechoic chamber has about a 10 dB SPL noise floor. Mark A. Castellano, Todd Hiers, and Rebecca Ma, "TMS320C6000 mu-Law and ALaw Companding with Software or the McBSP", Texas Instruments Application Report, SPRA634, April 2000. The lecture discusses mu-law companding used in the US and Japan (u = 255) and A-law companding in Europe (A = 87.6). In the companding formulas, the log is the natural logarithm. A student asked what happens when a call is placed from the US to Europe. Companding in telephony is to eight bits, with one bit for the sign. Hence, the formulas in terms of |x| in [0, 1] would be used to generate a seven-bit number. To the precision of seven bits, there is no difference between A-law companding (A = 87.6) and mu-law companding (u = 255) for |x| in [0.18, 1]. There is a mu-law pulse coded modulation (PCM) audio format. The format is an eight-bit floating-point format: 1 bit for the sign, 4 bits for the mantissa, and 3 bits for the exponent. This is a common audio format on Sun workstations.