The Bass Transmission Index: a new concept for evaluating loudspeaker performance

Loudspeaker design is a trade-off between optimising different aspects of performance with regard to the intended application. For musical mix monitoring, the ability to accurately reproduce the temporal envelope of dynamic signals is a key factor in helping to produce a balance of instruments
which will transfer well to other reproduction systems. Despite this, the industry standard still prioritises representations of the extension and flatness of the frequency response magnitude over transient accuracy, even for loudspeakers intended for professional use. This paper presents a method called the Bass Transmission Index (BTI), which aims to redress this balance and make it easier to evaluate and compare loudspeaker reproduction accuracy at low frequencies: a part of the audio spectrum that is crucial to most types of modern recorded music. Background and key information on the development of the method is presented, followed by an explanation of example data returned from analysis of some measured mix monitors.