Effect of Harmonicity on the Detection of a Signal in a Complex Masker and on Spatial Release from Masking

Abstract

The amount of masking of sounds from one source (signals) by sounds from a competing source (maskers) heavily depends on the sound characteristics of the masker and the signal and on their relative spatial location. Numerous studies investigated the ability to detect a signal in a speech or a noise masker or the effect of spatial separation of signal and masker on the amount of masking, but there is a lack of studies investigating the combined effects of many cues on the masking as is typical for natural listening situations. The current study using free-field listening systematically evaluates the combined effects of harmonicity and inharmonicity cues in multi-tone maskers and cues resulting from spatial separation of target signal and masker on the detection of a pure tone in a multi-tone or a noise masker. A linear binaural processing model was implemented to predict the masked thresholds in order to estimate whether the observed thresholds can be accounted for by energetic masking in the auditory periphery or whether other effects are involved. Thresholds were determined for combinations of two target frequencies (1 and 8 kHz), two spatial configurations (masker and target either co-located or spatially separated by 90 degrees azimuth), and five different masker types (four complex multi-tone stimuli, one noise masker). A spatial separation of target and masker resulted in a release from masking for all masker types. The amount of masking significantly depended on the masker type and frequency range. The various harmonic and inharmonic relations between target and masker or between components of the masker resulted in a complex pattern of increased or decreased masked thresholds in comparison to the predicted energetic masking. The results indicate that harmonicity cues affect the detectability of a tonal target in a complex masker.

Art as behaviour – an ethological approach to visual and verbal art, music and architecture

“…They observe a linear additivity of both effects, showing that the subjects profited from both harmonicity and binaural information. This is not in line with the results of Krumbholz et al (2009), probably due to Klinge et al (2011) measuring in the free field, where control of binaural cues available to the subjects is difficult. The linear additivity of modulation based and binaural cues, however, was also observed by Epp and Verhey (2009a), who found a linear combination of comodulation masking release (Hall et al, 1990) and binaural masking level difference (BMLD, e.g., Jeffress et al, 1956).…”

“…The detection threshold of a target tone, which is a component of a tone complex, is measured by adaptively decreasing its level until the stimulus can no longer be distinguished from a tone complex lacking the target tone (i.e., the reference stimulus). Klinge et al (2011) and Oh and Lutfi (2000) employed such a method. Both studies observed that the detection threshold for a target in a harmonic relationship to the rest of the tone complex (the masker) has a higher detection threshold than a mistuned target.…”

“…Depending on the resolvability, this can be attributed to the ability to "hear out" the mistuned target tone as mentioned above. In Klinge et al (2011) however, the components of the tone complexes were added up in sine phase, meaning that the reference and target intervals clearly differed in their envelope structure. This enabled the test subjects to identify the target interval by comparing the stimulus to a template that was learned in the course of the experiments.…”

“…periodicity) processing, with an integration stage that degrades temporal modulation information. Klinge et al (2011) studied the influence of mistuning and localization in the free field by presenting a mistuned or harmonic target component spatially separated with a different loudspeaker than the rest of the complex. The detection thresholds for the target component decreased with mistuning and spatial separation.…”

“…This masking release has been shown only indirectly in studies on mistuning detection (e.g., Moore et al, 1985;Hartmann et al, 1990), as they measured the just noticeable amount of mistuning using a paradigm in which the subjects compared mistuned complexes to harmonic complexes, while the amount of mistuning was adaptively varied. A direct investigation of the effect of mistuning on detection thresholds is possible in detection experiments, where a single component of a complex is the target signal that has to be detected, and the rest of the complex is regarded as the masker, effectively masking the component (Oh and Lutfi, 2000;Klinge et al, 2011). Here, the level of the target component is varied adaptively to obtain detection thresholds for various stimulus configurations.…”