| Abstract | The issue of architectural speech security is concerned with the degree to which rooms in buildings are acoustically isolated. For example, a conversation occurring within a room being intelligible to persons outside the room is indicative of a problem. To rate the degree to which transmitted speech is intelligible-or even audible-an objective measure is required. The measure should be calculable from the received speech signal spectrum and the background noise spectrum, and it should be highly correlated with responses from actual listeners. This report describes the design and results of listening tests in which intelligibility scores and audibility ratings were related to a variety of objective measures, calculated from the speech and noise spectra. Existing measures such as Articulation Index (AI), Speech Intelligibility Index (SII), A-weighted level difference, and loudness are included, as well as several different weighted signal-to-noise ratios. The weightings place varying degrees of importance on different frequency bands, as it is known the hearing system response varies with frequency. |
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