The effect of the helicotrema on low-frequency loudness perception

Abstract

Below approximately 40 Hz, the cochlear travelling wave reaches the apex, and differential pressure is shunted through the helicotrema, reducing hearing sensitivity. Just above this corner frequency, a resonance feature is often observed in objectively measured middle-ear-transfer functions (METFs). This study inquires whether overall and fine structure characteristics of the METF are also perceptually evident. Equal-loudness-level contours (ELCs) were measured between 20 and 160 Hz for 14 subjects in a purpose-built test chamber. In addition, the inverse shapes of their METFs were obtained by adjusting the intensity of a low-frequency suppressor tone to maintain an equal suppression depth of otoacoustic emissions for various suppressor tone frequencies (20-250 Hz). For 11 subjects, the METFs showed a resonance. Six of them had coinciding features in both ears, and also in their ELC. For two subjects only the right-ear METF was obtainable, and in one case it was consistent with the ELC. One other subject showed a consistent lack of the feature in their ELC and in both METFs. Although three subjects displayed clear inconsistencies between both measures, the similarity between inverse METF and ELC for most subjects shows that the helicotrema has a marked impact on low-frequency sound perception.

Archives of Acoustics

“…Overall, these results suggest that the sensation level and/or loudness of the lowest harmonics plays an important role in F0 discrimination for low F0s. Due to the steep frequency dependence of sound transmission through the middle ear to the cochlea for frequencies below 100 Hz (Marquardt et al, 2007;Jurado, Marquardt, 2016), the relative and absolute levels of the individual components may also play an important role in determining the OLLP.…”

Archives of Acoustics

“…There is increasing awareness of environmental noise in the infrasound (IS, < 20 Hz) and low-frequency (LF, 20-200 Hz) ranges (Pedersen et al, 2008;Alves et al, 2015;Yamada et al, 2016). Although absolute hearing sensitivity decreases with lowering frequency as a result of peripheral mechanisms (Cheatham, Dallos, 2001;Jurado, Marquardt, 2016), the annoyance and decrease in life quality resulting from prolonged exposure to IS and LF, particularly those associated with emissions from wind turbines, has recently received much attention (e.g. Leventhall, 2009;Schmidt, Klokker, 2014;Baliatsas et al, 2016).…”