Psychoacoustic Metrics Research Articles

Role of Upper Airway Dimensions in Snore Production: Acoustical and Perceptual Findings

While considerable efforts have been expended to develop snore-driven markers for detecting obstructive sleep apnea (OSA), there is little emphasis on the relationship between the human upper airway (UA) dimensions and the attributes of snores. This paper aims to investigate the acoustical and perceptual impacts of changing the cross-sectional areas (CSA) of the pharynx and oral cavity on the production of snores. Synthetic snores were generated based on the source-filter theory, whereas natural snores were recorded from 40 snorers during nocturnal polysomnography. First formant frequency (F1), spectral peak frequency (PF), and psychoacoustic metrics (loudness, sharpness, roughness, fluctuation strength, and annoyance) of CSA perturbations were examined, completed with diagnostic appraisal of F1 and PF for single- and mixed-gender groupings using the receiver operating characteristic curve analysis. Results show that (1) narrowing the pharyngeal airway consistently increases F1, but not for PF; and (2) altering the airway dimensions yield no considerable differences in perception of snore sounds, but indirectly affect the psychoacoustics by changing the dynamics of snore source flow. Diagnostic outcomes for all groupings (p-value < 0.0001) demonstrate that F1 is more capable of distinguishing apneic and benign snorers than PF due to the close association of F1 with the UA anatomical structures. Correlation exists between the UA anatomy and the properties of snores; there is a promising future for developing snore-driven screening tools for OSA.

Salience of spatial attributes on quality evaluation of multichannel audio processing devices

Objective quality assessment methods for audio signal processing devices, e.g. ITU-R BS.1387-1, measure perceived quality by using various types of test excerpts and incorporating a number of psychoacoustic metrics for evaluating various attributes of quality degradations. As many multichannel audio processing devices are being developed, recent quality assessment methods include not only timbral features but also spatial features, such as analysis on interaural disparities. In this paper, the importance of the newly proposed spatial - interaural - features are studied for different types of multichannel test signals. The spatial features have bigger salience on directly recorded sound sources than artificially manipulated multichannel contents.

Active control of engine noise transmitted into cavities: simulation, experimental validation and sound quality assessment

Active control has been proposed as a possible solution to cope with low frequency noise reduction in vehicles. Active noise control systems tend to be designed with a target on the sound pressure level reduction. However, the perceived control efficiency for the occupants can be more accurately assessed if psychoacoustic metrics are taken into account. The aim of this paper is to evaluate, numerically and experimentally, the effect of a collocated velocity feedback controller on the sound quality of engine noise in a vehicle mockup. The simulation scheme is described and experimentally validated. The engine excitation is provided by a sound quality equivalent engine simulator, running on a real-time platform that delivers harmonic excitation in function of the driving condition. The controller performance is evaluated in terms of sound quality metrics such as specific loudness and roughness. As a result of the control action, loudness is significantly reduced and roughness slightly spread, with an overall improvement on the perceived engine sound.

Active sound quality control of engine induced cavity noise

Active control solutions appear to be a feasible approach to cope with the steadily increasing requirements for noise reduction in the transportation industry. Active controllers tend to be designed with a target on the sound pressure level reduction. However, the perceived control efficiency for the occupants can be more accurately assessed if psychoacoustic metrics can be taken into account. Therefore, this paper aims to evaluate, numerically and experimentally, the effect of a feedback controller on the sound quality of a vehicle mockup excited with engine noise. The proposed simulation scheme is described and experimentally validated. The engine excitation is provided by a sound quality equivalent engine simulator, running on a real-time platform that delivers harmonic excitation in function of the driving condition. The controller performance is evaluated in terms of specific loudness and roughness. It is shown that the use of a quite simple control strategy, such as a velocity feedback, can result in satisfactory loudness reduction with slightly spread roughness, improving the overall perception of the engine sound.

Influence of sound and vibration from sports impacts on players' perceptions of equipment quality

The transition from traditional to modern materials has had a significant effect on equipment performance in many sports. As a result, governing bodies are increasingly placing performance limits on equipment and so other characteristics are becoming important to players seeking the most desirable equipment for their game. The ‘feel’ of the equipment is one such subjective characteristic, which has also been significantly affected by changes in material, but it is difficult to define. Tactile and auditory sensations from impact have been found to contribute to the feel of a shot in several sports and this paper provides further evidence of this relationship. Using golf as an example, this study presents a method for measuring and analysing players' subjective perceptions. The results are then correlated with measurements of sound, linear vibration, and torsional vibration from impact. Stronger relationships were found with the sound data rather than the vibration data, suggesting that the sound is the most significant form of feedback from impact. Psychoacoustic metrics for assessing sound quality are discussed, including perceived loudness and sharpness. Relationships were found between these metrics and the players' perceptions although similar correlations were also found with traditional metrics, such as sound pressure level. The limitations of the psycho-acoustic models for impulsive sounds are also discussed.

Correlations between deficiencies in power window systems influencing sound quality and some psychoacoustic metrics

The perceptual auditory attributes principally responsible for the annoyance quality of certain deficiencies in power window systems are identified and quantified experimentally with a set of psychoacoustic metrics. A group of measured sound signatures and the corresponding window translation velocities in over 30 production passenger vehicles are examined in this sound quality study. These measurements are acquired using a relatively simple non-destructive setup situated in a large hemi-anechoic chamber. An analysis is performed to map the specific amplitude, temporal and spectral characteristics of the measured sound and velocity data to the subjective attributes that influence perceived annoyance response significantly. The annoyance level is quantified using a normalized preference scale that is obtained from the paired comparison tests taken by 70 human subjects with normal hearing range. The study shows that sounds depicting higher intensity, pitch, transient effect, and time-varying character are found to be more annoying. These results provide a comprehensive set of information that can be used in product design and trouble-shooting phases to reduce overall noise quality complaints.