In This Section
Synchronized Swept-Sine: Theory, Application, and Implementation - October 2015
Effect of Microphone Number and Positioning on the Average of Frequency Responses in Cinema Calibration - October 2015
The Measurement and Calibration of Sound Reproducing Systems - July 2015
Journal of the AES
2014 May - Volume 62 Number 5
A study of preferred listening environments among fifteen sound engineers illustrates the universal principle that “one size does not fit everyone.” By using the measured impulse responses of nine studio control rooms that were then encoded using the Spatial Decomposition Method, each space was simulated in an anechoic chamber with a 30-channel reproduction system. Preferences depended on the occupation of the sound engineer and on the nature of the song. While mixing engineers preferred acoustically dry environments with high clarity, mastering engineers preferred more reverberant environments with less clarity. Reverberation and clarity appear to be the dominant dimensions for preference. Extensive interviews with the subjects provided more nuanced explanations of how the sound engineers experience a listening space.
Inter- and Intra-Individual Variability in the Blocked Auditory Canal Transfer Functions of Three Circum-Aural Headphones
When using headphone playback, there are many factors that contribute to variations of the intended stimuli: errors in headphone transfer functions, their inter-individual differences, and the intra-individual variability due to repeated positioning. This report provides a detailed evaluation of the blocked auditory canal transfer characteristics for one specimen of each of three different circumaural headphones frequently used in psychoacoustics and audio production; two headphones based on electrodynamic, one headphone based on an electrostatic converters. Depending on the headphone, results showed inter-individual variations up to 10 dB in the blocked auditory canal entrance headphone transfer function magnitude spectra and 0.5 ms in the corresponding group delays, especially at frequencies above 6 kHz. At lower frequencies, 2 dB and 0.1 ms were measured. This general behavior is comparable for all three headphone specimens, but each model shows specific peculiarities of the headphone transfer function magnitude and group delay. For all headphones studied, the inter-individual magnitude spectrum variability exceeded the average intra-individual variability.
Although the common procedure for measuring sound quality is based on subjective listening tests, this approach is labor intensive, requiring a large number of trained subjects and specialized facilities. If a model-based approach could approximate subjective tests, quality measurement could be automated. This study examines the degree to which objective measures from auditory models might improve the prediction of quality ratings by normal-hearing subjects with different types of distortion. Using a wide variety of audio data, the authors compared two sound quality assessment models based on PEMO-Q and CASP and one extended version of PEMO-Q to state-of-the-art quality-assessment models. The results revealed that the suggested quality models were able to predict a high range of different distortions and performed best compared to other state-of-the-art quality measures. In general, quality measures employing valid auditory models generalized best across different kinds of distortions.
While adding a height dimension to a surround sound system implies the addition of loudspeakers on the ceiling, this study explores the means for synthesizing the 3rd dimension by signal processing. Creating a virtual elevated auditory image by using the conventional lateral 5.1 loudspeaker configuration greatly simplifies the burden on the consumer. The proposed system has been implemented using a crosstalk-cancellation method optimized for three of the five channels in a home-theater system: center, left-surround, and right-surround. This hybrid method, based on earlier work by Klepko, required the calculation of two inverse filters. Preliminary listening tests showed that loudspeakers at ear level could render sound sources perceived to be at higher elevations, and that the perceived elevation angles increased monotonically with the target elevation angles.
The conventional design of an omnidirectional source uses a polyhedral speaker to emulate a spherical radiating sound wave. But this approach does not work at short distances and at higher frequencies. The inverse horn design proposed by Polack, a conventional loudspeaker matched to a small aperture through a reverse horn, provides a good approximation to an omnidirectional point source. But this solution has a rather irregular frequency response that arises from the acoustic resonances of the air inside the horn cavity. This research described two implementations of an equalized reverse horn source that have the desired directional characteristics of a point source with a flat frequency response of +/-3 dB from 100 Hz to 8 kHz. There are various trade-offs in selecting the sizes.
Standards and Information Documents
AES Standards Committee News
Digital audio measurement; digital audio interfaces; audio file transfer and exchange
Dialog editing and mixing, music, and sound design are the cornerstones of the art of making sound for cinema and television. During master classes at a recent AES convention, world-renowned practitioners of these skills shared the benefit of their wisdom.
The (literally) deafening restaurant blare grows louder and louder as people increase their volume to make themselves heard over the continually amplifying clamor. It’s a classic lose/lose situation. However, this problem can be easily and cost-effectively controlled, by applying appropriate acoustical treatments to walls and ceilings. Imagine people talking to their hearts content at dinner without having to outshout each other over their pasta. That’s a pretty appetizing culinary concept.
56th Conference, London, Call for Papers
57th Conference, Hollywood, Call for Papers