Directional loudness

  • Sivonen, Ville Pekka (Project Participant)
  • Ellermeier, Wolfgang (Project Participant)

Project Details

Description

Current sound-quality evaluation algorithms are basically monaural. That is they are not defined for the natural case of listening with two ears receiving different input. Even for loudness, the most developed sound-quality attribute, it is unclear, how binaural loudness should be computed. Most studies investigating binaural loudness have been restricted to presenting tones (or noise) at different interaural levels via headphones. Only very few studies (the latest comprehensive one dating more than 40 years back) have addressed true directional loudness of real sound sources positioned in space. The scope of these studies shall be extended in several ways (1) by using narrow-band signals (rather than wide-band noise) that may reveal frequency specific effects of direction on loudness, (2) by studying the phenomenon at different absolute levels for which different degrees of summation are to be expected, (3) by using modern (adaptive forced-choice) psychophysical techniques to obtain unbiased loudness matches, and (4) while measuring the effective signal reaching the ear by determining individual head-related transfer functions (HRTFs). The results from the first listening experiment in an anechoic room show that loudness is not constant over sound incidence angles. The directional loudness matches between the loudspeakers vary over a range of 10 dB, and show considerable frequency dependency. The pattern of results also varies substantially between subjects, but can be largely accounted for by inter-individual variations in their HRTFs. Based on the results, a binaural loudness model applicable for artificial-head measurements has been developed. Further experiments were carried out, investigating directional loudness both for narrow- and wideband, as well as reverberant stimuli. (Center contract)
StatusFinished
Effective start/end date31/12/200731/12/2007