In English

Evaluation of metrics and methods for objective quantification of interior diesel engine idling sound

Ann-Marie Longworth ; Erik Thysell
Göteborg : Chalmers tekniska högskola, 2004. Rapport E - Chalmers tekniska högskola, Avdelningen för teknisk akustik., ISSN 0283-8338; E04-09, 2004.
[Examensarbete på avancerad nivå]

The automotive industry is highly competitive and sound quality is today an increasingly important factor. Today diesel vehicles have good performance and becoming more and more popular due to low fuel consumption and low CO2 emission. The Noise Vibration and Harshness (NVH) properties are improving constantly. Jaguar has just recently launched diesel vehicles onto the market however Land Rover has produced diesels for a long time. Still neither of these companies has a metric or method that can successfully be used for the characterisation of diesel sound.For engines working with NVH it is important to work against a set target. To be able to have a set target it is essential to first have an objective metric, which shows high correlation to subjective ratings, where the metric is easy to understand and implement. The aim of this work has been, by evaluation of already existing metrics and methods, to find the best possible way to characterise and quantify diesel sound. This also includes finding the best possible means of illustrating the diesel character. Various metrics and methods where evaluated by running listening studies. Both generally known psychoacoustic metrics and software that recently have become available where evaluated by correlating objective values to subjective ratings. Findings show that Loudness or Sound Pressure Level cannot alone be used to characterise the diesel sound even though they are vey important factors in Sound Quality. It has been shown that no combination of generally known psychoacoustic metrics, at least not without modification, is sufficient to fully characterise diesel sound. However by using methods based on signal modulation analysis gives high correlation to subjective ratings. Methods utilising this approach has been found to sufficiently characterise and quantify diesel sound.

Nyckelord: diesel, engine, sound, vibration, harshness, modulation, dki, mdi, knock, knocking, impulse, impulsive, impulsiveness, loudness, dieselness

Publikationen registrerades 2006-09-28. Den ändrades senast 2013-04-04

CPL ID: 461

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