This work describes an activity that allowed to realize a modified NIST MarkIII array. This system is able to acquire 64 synchronous audio signals at 44.1 kHz and is primarily conceived for far-field automatic speech recognition and speaker localization. Preliminary experiments conducted on the original array had showed that coherence among a generic pair of signals was affected by a bias due to common mode electrical noise, which turned out to be detrimental for time delay estimation techniques applied to co-phase signals or to localize speakers. A hardware intervention was realized to remove each internal noise source from analog modules of the device. The modified array provides a quality of input signals that fits results expected by theory.
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