Measurement of sound quality for critical listening

Abstract

For the critical assessment of music recordings the uniformity of the pressure amplitude response with respect to frequency has robustly been defended as one of the principals of prime importance for any electro-acoustic monitoring system. This has been particularly so in the appraisal of the room responses, where non-linear factors such as intermodulation distortions do not apply. However, despite the traditional emphasis being placed on the even distribution of modal and diffuse energy, recent investigations have begun to indicate that the uniformity of the modal decay rate is far more important than has previously been appreciated in terms of the definition of accurate and revealing monitoring acoustics. Parallel work on loudspeaker systems has also been tending to lead to similar conclusions. Modulation transfer function related experiments have begun to demonstrate how the effects of temporal response smearing can significantly reduce the ability of any room/loudspeaker system to convey to the ears of the listeners the complex details within musical recordings. Measurements in real control rooms, and work on the subjective perception of room modes based on binaural room simulations, have now begun to highlight the importance of fast and uniform temporal decays over the whole audio frequency band where monitoring accuracy is a prime requirement. Studies on factors such as modal distribution and decay rates have revealed perception biases that indicate their relative importance in defining perceptually accurate monitoring conditions. The emerging trend is that to achieve such conditions, the temporal response of electro-acoustic systems must be considered at all times, and the all-pervading pre-eminence of the pressure amplitude response may have to be compromised