ABSTRACT
Objectively determined single-number-quantities (SNQs) describing the airborne sound insulation of a façade should correspond to the subjective perception of annoyance to road traffic sounds transmitted through a façade. The reference spectra for spectrum adaptation terms C and Ctr in standard ISO 717-7 (International Organization for Standardization, 2013) are not based on psycho-acoustic evidence. The aim of this study is to develop reference spectra which result in SNQs that explain the subjective annoyance of road traffic sounds transmitted through a façade well. Data from a psycho-acoustic experiment by Hongisto, Oliva, and Rekola [J. Acoust. Soc. Am. 144(2), 1100-1112 (2018)] were used. The data included annoyance ratings for road traffic sounds (five different spectrum alternatives) attenuated by the façade (twelve different sound insulation spectrum alternatives), rated by 43 participants. The reference spectrum for each road traffic spectrum was found using mathematical optimization. The performance of the acquired SNQs was estimated with nested cross-validation. The SNQs determined with the optimized reference spectra performed better than the existing SNQs for two road traffic spectra out of five and for an aggregate of the five road traffic sound types. The results can be exploited in the development of standardized SNQs.
Subject(s)
Noise , Sound , Acoustics , Humans , MathematicsABSTRACT
It has been long recognized that the single-number quantities presented in the standard ISO 717-2 [(2013) International Organization for Standardization] do not correlate especially well with the subjective judgment of living impact sound sources directed to the floors. The aim of this study was to find single-number quantities which are well associated with the subjective annoyance caused by different impact sounds. Experimental data of laboratory measurements of impact sound insulation of floors and a psychoacoustic experiment was used [Kylliäinen et al. (2017). Acta Acust. Acust. 103, 236-251]. The five studied impact sound types were walking with hard shoes, socks, and soft shoes, super ball bouncing, and chair moving. A fundamental requirement was that the single-number quantities can be expressed as the sum of L'n,w or L'n T, w and a spectrum adaptation term. Reference spectra were derived by the means of a mathematical optimization method. Reference spectra for each sound type were defined separately. An optimized reference spectrum based on all five sound types explained the annoyance of these sound types reasonably well (r2 = 0.93) and better than any of the standardized single number quantities (e.g., r2 = 0.86 for L'n,w + CI,50-2500).
ABSTRACT
Amplitude modulation exists in many environmental noise types. A penalty has been suggested for legal noise assessment to such sounds, but the scientific evidence is limited. The purpose of this research was to determine the annoyance penalty of amplitude modulated (AM) sound as a function of the modulation frequency fm and depth Dm. A psychoacoustic laboratory experiment was conducted with 40 participants to explore how subjective loudness and annoyance of AM sound depends on fm (from 0.25 to 16 Hz), Dm (from 1 to 14 dB), and overall spectrum (two alternatives). The sounds consisted of both AM sounds and reference sounds without amplitude modulation. The AM sounds were played at 35 dB LAeq, which is typical for environmental noise both indoors and in residential yards. The annoyance penalty increased with increasing fm and Dm. The penalties varied from 4 to 12 dB, when Dm ranged from 4 to 14 dB and fm ranged from 1 to 16 Hz. For the lowest fm= 0.25 Hz, and Dm = 1 dB, no penalty could be suggested. The results suggest a potential need for a penalty for low-level AM sounds for certain ranges of fm and Dm, applied for the periods with AM sound.
ABSTRACT
ISO 717-1 [(1996). International Organization for Standardization, Geneva, Switzerland] and ASTM 413 [(2010). American Society for Testing and Materials International] define various single-number quantities (SNQs) that are commonly used to rate objectively airborne sound insulation of constructions. Recent psychoacoustic evidence suggests that none of them is appropriate for a wide range of living sound stimuli. The purpose of the study was to develop an alternative compromising SNQ for the frequency range 50-5000 Hz that explains well the annoyance caused by various airborne living sounds transmitted from the neighboring dwelling. Optimal reference spectra for different living sounds were found by mathematical optimization. Experimental data from a psychoacoustic laboratory study [Hongisto, Oliva, and Keränen (2014). Acta Acust. Acust. 100, 848-863] were utilized. The subjects (n = 59) had evaluated the disturbance of living sounds that were electrically filtered to mimic transmission through commonly used wall structures. To find a high-performing reference spectrum for living sounds in general, the optimized reference spectra were averaged over all sound types. The resulting SNQ was called Rw + Copt. The related reference spectrum deviates significantly from the reference spectrum for living activities, C50-5000, below 315 Hz. The suggested SNQ correlates better with the subjective disturbance caused by living sounds than any of the present standardized SNQs of ISO 717-1 or ASTM 413.
