171 research outputs found

    PegelabhÀngigkeit des Overshoots in statistischen und reproduzierbaren Rauschmaskierern

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    Es wurden Messungen zur zeitlichen Struktur der Simultanverdeckung in statistischen und reproduzierbaren Rauschmaskierern vorgestellt. Bei den Experimenten in frozen noise wurde die Wechselwirkung zwischen Testsignal und Feinstruktur des Maskierers berĂŒcksichtigt. Die Mithörschwellen zeigen ein AbhĂ€ngigkeit von der Anfangsphase des Testtones. Daher wurden die Messungen zum OvershootphĂ€nomen in frozen noise fĂŒr die beiden Testtonphasen durchgefĂŒhrt, bei denen die Schwellen in den Experimenten zur PhasenabhĂ€ngigkeit ihren maximalem bzw. minimalen Wert annehmen. Ein Zusammenhang zwischen dem Einfluß der Phase auf die Mithörschwellen und der GrĂ¶ĂŸe des Overshoot tritt besonders deutlich bei einem Rauschpegel von 50 dB SPL auf. Aufgrund des großen Signal-RauschverhĂ€ltnisses zu Maskiererbeginn ist dort die PhasenabhĂ€ngigkeit verglichen mit den Resultaten am Maskiererende sehr gering. Die Ergebnisse zeigen, daß der Overshoot in frozen noise sowohl von der Startphase des Testtones als auch vom Rauschpegel abhĂ€ngt. Die Overshootwerte, die fĂŒr die beiden Phasen in frozen noise ermittelt wurden, bilden i.a. die obere und untere Begrenzung fĂŒr die Werte in running noise. Die Möglichkeit zur Auswertung der Maskiererfeinstruktur fĂŒhrt demnach nicht generell zu einer Verringerung des Overshoots

    Effect of masker level on overshoot in running‐ and frozen‐noise maskers

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    Masked thresholds were measured with running‐ and frozen‐noise maskers. The 5‐kHz signal was 2 ms in duration. The masker was low‐pass noise (20 Hz–10 kHz); its total duration was 300 ms. The overall level of the masker was 30, 50, or 70 dB SPL. The onset of the signal was delayed by 0, 3, 8, 18, 198, or 278 ms relative to the onset of the masker. In all frozen‐noise measurements, the signal was added to the same fine structure of the noise. Overshoot in frozen noise was measured for two starting phases of the signal that led to a 10‐dB difference for large signal‐onset delays. In all three configurations (running noise and frozen noise with two different signal phases) masker level had a similar influence on overshoot. At the intermediate masker level (50 dB SPL), a significant amount of overshoot (up to 15 dB) was observed in all three conditions. At the low and the high masker levels, overshoot was very much reduced, and even became negative in most conditions for the 30‐dB‐SPL masker. For the 50‐dB frozen‐noise masker, the total variation of thresholds with signal phase was 8 to 11 dB for long signal‐onset delays, but only 3 to 6 dB for short delays. For the low‐ and high‐level maskers, where only a small overshoot was observed, the threshold variation with phase for a signal at masker onset was the same as that for the long‐delay condition. An explanation for the variation of signal detectability with masker level is proposed that refers explicitly to the compressive input–output characteristic of the basilar membrane at intermediate levels

    The Effect of Background Noise on a "Studying for an Exam"Task in an Open-Plan Study Environment: A Laboratory Study

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    Students can be disturbed by background noise while working in an open-plan study environment. To improve the acoustic quality of open-plan study environments a study was done on the influence of different sound scenarios on students working on a typical student task, “studying for an exam”. Three sound scenarios and a quiet reference sound scenario were developed, based on the sound environment of a real open-plan study environment, with a varying number of talkers in the background and different reverberation times of the study environment. Seventy students worked on a set of tasks simulating a “studying for an exam” task while being exposed to the sound scenarios. This task comprises a reading comprehension task with text memory by delayed answering questions about the text, with additional tasks being performed in the gap between studying the text and retrieving. These additional tasks are a mental arithmetic task and a logical reasoning task. Performance, self-estimated performance and disturbance of students were measured. No significant effect of the sound scenarios was found on performance of students working on the reading comprehension task with text memory and the mental arithmetic task. However, a significant effect of sound was found on performance of students working on the logical reasoning task. Furthermore, a significant effect of the sound scenarios was found on self-estimated performance and perceived disturbance for all tasks from which the reading comprehension task with text memory was the most disturbed task. It is argued that the absence of a detrimental sound effect on the performance of students working on a reading comprehension task with text memory is a result of focusing due to task engagement and task difficulty, both aspects working as a “shield against distraction”

    Messungen zum OvershootphÀnomen in monauralen und diotischen Konfigurationen

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    Es wurden Messungen zur zeitlichen Struktur der Simultanverdeckung von Breitbandrauschen vorgestellt. Dabei zeigte sich, daß die Mithörschwellen zu Beginn des Maskierers nicht immer erhöht sein mĂŒssen (positiver Overshoot), sondern durchaus auch niedriger liegen können als zu spĂ€teren Zeitpunkten im Maskierer (negativer Overshoot oder Undershoot). Des weiteren wurde festgestellt, daß dieses PhĂ€nomen sich in monauralen und diotischen Konfigurationen pegelabhĂ€ngig verhĂ€lt. Das Maximum des Overshoots tritt bei mittleren Rauschpegeln auf. Es konnte gezeigt werden, daß es sich bei dieser PegelabhĂ€ngigkeit des Overshoots um eine Abweichung vom Weberschen Gesetz handelt, die sich mit der zeitlichen Lage des Testtones im Maskierer Ă€ndert. Ebenfalls zeit- und pegelabhĂ€ngig ist die Differenz zwischen den monauralen und den diotischen Schwellen. Bei hohen Maskiererpegeln können die diotischen Schwellen deutlich höher liegen als die monauralen. Dieses ungewöhnliche PhĂ€nomen und der Overshoot ĂŒberstreichen den gleichen Zeitbereich
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