What is it about?

Listeners are remarkably good at discerning individual sound sources when many sounds occur together. This process is known as Auditory Scene Analysis, which relies on taking advantage of expected patterns of sounds called Acoustic Natural Regularities. In this study we test one natural regularity, first to confirm that it occurs in music and speech, and second to test if it helps listeners discern and track individual sound sources. Here the natural regularity is a correlation between changes in acoustic intensity and fundamental frequency of a sound source. Perceptually, this is experienced as loudness and pitch changing together. The first three experiments confirm the natural regularity that in music and speech people produce and vocalize sounds that typically get higher when intensity increases and lower when it decreases. The fourth study confirms that people can hear sounds better when intensity and frequency change together in a manner consistent with the expected natural regularity. The findings support that the occurrence of acoustic natural regularities like the correlation between changes in intensity and fundamental frequency help listeners to better track individual sound sources.

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Why is it important?

The history of the advancement of science is that of people noticing natural patterns and then using that knowledge to develop new improved strategies and technologies. Here confirming the regularity of the correlation between acoustic frequency and intensity has promise to be beneficial to both the design of automated sound-parsing and auditory recognition systems, as well as perceptual interface technologies like hearing aids. On a more aesthetic level, elucidating perceptual tendencies can help us better understand things like the qualities that make music pleasing, and why we perceive some kinds of auditory illusions. In short, listeners expect sound sources to get higher when they get louder, which is both easier to hear, and tends to sound more natural and pleasing.

Perspectives

This was a fun study to run and in some ways produced results that are obvious, but hadn't been clearly articulated before. When we yell, our voices routinely get higher, and it is frequently difficult for those learning music to keep from playing high notes louder, especially on wind instruments. It is pleasing to do research that taps into both perceptual and aesthetic principals as this does.

Michael McBeath

Read the Original

This page is a summary of: Natural Regularity of Correlated Acoustic Frequency and Intensity in Music and Speech: Auditory Scene Analysis Mechanisms Account for Integrality of Pitch and Loudness, Auditory Perception & Cognition, April 2019, Taylor & Francis,
DOI: 10.1080/25742442.2019.1600935.
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