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May 1984

Volume 75, Issue S1, pp. S1-S93

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back to top Session W. Psychological Acoustics V: Loudness and Intensity
Contributed Papers
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Profile information improves Weber fraction (A)

David M. Green and Christine R. Mason

J. Acoust. Soc. Am. Volume 75, Issue S1, pp. S44-S44 (1984); (1 page)

Online Publication Date: 12 Aug 2005

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We measured the ability of observers to detect an increment in the intensity of a 100‐ms 1000‐Hz sinusoid under two conditions. In the first condition, the observer heard single 1000‐Hz sinusoids —either the standard or the standard plus the increment. In the second condition, ten other sinusoids were added to the 1000‐Hz sinusoid with frequencies ranging from 200 to 5000 Hz. These additional components were equal in intensity to the standard and the frequency ratio between successive components of the 11‐component complex was 1.38. The basic task for each condition was the same, to detect an increment in the 1000‐Hz component. The increment was easier to detect in the complex spectrum or “profile,” presumably because the additional components allow one to make simultaneous comparisons among the different components. Only a successive comparison between the 1000‐Hz components was possible in the single sinusoid condition. The improvement is as much as 10 dB for some observers and conditions, when expressed in terms of the signal relative to the standard. [Work supported by NIH.]
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Factors affecting descending binaural loudness balance (A)

I. M. Young and L. D. Lowry

J. Acoust. Soc. Am. Volume 75, Issue S1, pp. S44-S44 (1984); (1 page)

Online Publication Date: 12 Aug 2005

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The control continuous tone (1000 Hz) was presented in one ear starting at an intensity of 100 dB SPL with an attenuation rate of 1 dB per second by descending manner. The balancing comparison continuous tone (1000 Hz) was presented in the opposite ear also starting at 100 dB SPL with an attenuation rate of 5 dB per second. Three trained subjects with normal hearing were instructed to release the Bekesy switch to increase the loudness and to push the switch to reduce the loudness of the comparison tone. While there were inter‐subject variations, our data indicated that there was continuous decrease in the ratio of balanced loudness levels between tones with attenuation rates of 5 dB per second and 1 dB per second as the functions of time and decreasing intensity. This is considered a manifestation of normal adaptation. Present results were compared with our previous reports for the threshold differences produced by different attenuation rates at the suprathreshold starting intensities.
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Perceived magnitude of two‐tone‐noise complexes (A)

Rhona P. Hellman

J. Acoust. Soc. Am. Volume 75, Issue S1, pp. S44-S44 (1984); (1 page)

Online Publication Date: 12 Aug 2005

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Overall perceived magnitude (loudness, annoyance, and noisiness) of estimation. The stimuli were tone pairs added to a low‐pass noise that was attenuated by 5 dB/oct above 600 Hz. The low‐frequency tonal component remained at 250 Hz, while the high‐frequency component was set, in separate sessions, at 275, 350, 500, 1000, and 3000 Hz. Listening was binaural through earphones. Within a session, the experimental variables consisted of the SPLs of the added tones, the SPL of the noise, and the tone‐to‐noise ratios relative to the appropriate 1/3‐octave‐band pressure levels. Data analysis showed that perceived magnitude is a complex function of the overall SPL of the noise‐tone‐complex, the frequency separation (ΔF) between the tonal components, and tone‐to‐noise ratio. The results are related to underlying mechanisms governing loudness and masking. The possible role played by consonance and dissonance effects described by Plomp and Levelt [J. Acoust. Soc. Am. 38, 548–560 (1965)] is also discussed. [Work supported by NASA Langley Research Center.]
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Comparative redundancy as an influence on loudness (A)

Ernest M. Weiler, David Sandman, Frederick Cobb, and James M. Davis

J. Acoust. Soc. Am. Volume 75, Issue S1, pp. S44-S44 (1984); (1 page)

Online Publication Date: 12 Aug 2005

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Adaptation to a stimulus environment often implies suppression of the redundant features in favor of stimuli carrying more information. Study of auditory adaptation of a continuing (redundant) stimulus, also requires consideration of the less redundant “comparison” stimulus. A magnitude estimation loudness adaptation study (1 kHz, 60 dB) designed to parallel the steps of the SDLB technique, yielded the following: (a) no loudness adaptation occurred during the pre‐test baseline when binaural simultaneously intermittent stimuli were presented, (b) immediately afterward, 7 min. of continuous redundant monaural stimulation yielded negatively accelerated adaptation, (c) finally, restoration of intermittent stimulation in the contralateral ear, resulted in apparent binurally “induced” adaptation of the continuous tone, but not of the less redundant intermittent tone. Previously, monaural heterophonic balances (Weiler and Friedman, 1973, etc.) resulted in the decline of the continuous (redundant) tone in the presence of an intermittent comparison tone. In summary, adaptation occurs in the more redundant stimulus when the two are competitive, similar, and in the same frame of reference.
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Intensity discrimination in chinchillas (A)

Bhagyalakshmi G. Shivapuja, Samuel S. Saunders, and Richard J. Salvi

J. Acoust. Soc. Am. Volume 75, Issue S1, pp. S44-S45 (1984); (2 pages)

Online Publication Date: 12 Aug 2005

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Previous research using amplitude modulated noise has suggested that the intensity discrimination thresholds of the chinchilla would be larger than those of humans. Consequently, intensity discrimination thresholds (ΔI) were measured in the chinchilla using a positive reinforcement technique. Intensity discrimination thresholds were obtained at several different frequencies over a range of sensation levels. In general the intensity discrimination thresholds improved as the sensation level increased. The smallest intensity discrimination thresholds obtained were approximately two to three times larger than those for humans. Furthermore, the effect of sensation level on intensity discrimination threshold was more pronounced in the chinchilla than in man. Results and their implications will be discussed.
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