Nowadays, the improvement of the noise climate at the operator station of construction machines is a key issue. In fact, the 2003/10/EC Directive on health and safety requirements for noise exposure at work has currently being transposed in all the European Member States, introducing lower noise limits. On the other hand, the market requests are more and more oriented to machines with high-level performances and this trend is making noise one of the key factors for facing the strong competition. In this context, a research project is in progress aiming at characterising the noise climate at the operator station of skid steer loaders during actual working conditions. This paper, in particular, presents some results of a series of binaural measurements carried out at the operator station of three compact loaders, different for dimension and power, with two main goals. Firstly, to investigate in more detail the suitability of the different physical and psycho-acoustic parameters in specifying the "character" of these kinds of noise signals. Then to identify which parameters describe at best the auditory perception of these signals with respect to some desired conditions of comfort. Subjective listening tests performed on these three different compact loaders handling gravel and loam showed that sharpness and loudness are the parameters which correlate best to the subjective perception of annoyance. In addition, the use of a proper metric based on the spectral and temporal analysis of both acoustic (Fig. 4) and psychoacoustic (Fig.3) parameters permitted to deeply investigate which machine characteristics and/or working conditions are more related to the auditory perception. In fact, noise components generated by the hydraulic system and noise components associated with the machine working with gravel turned out to have the greatest impact on the annoyance judgments. This is because they influence both the medium-high frequency range affecting the sharpness values and the loudness variation over time.
Il lavoro presenta alcuni risultati di uno studio volto a caratterizzare il rumore presente al posto guida di pale caricatrici compatte durante normali condizioni di lavoro. A tal fine, registrazioni binaurali sono state effettuate al posto guida di tre diverse pale caricatrici mentre ciascuna macchina svolgeva lo stesso ciclo di lavoro comprendente una fase di carico materiale e una di traslazione. Per mettere in evidenza linfluenza del tipo di materiale sul livello di disturbo a cui è sottoposto loperatore, ogni ciclo di lavoro è stato ripetuto con due diverse tipologie di materiale (ghiaia e terra). I segnali acquisiti sono stati analizzati in termini di parametri acustici e psicoacustici e successivamente utilizzati in specifiche sessioni di ascolto, per identificare le grandezze meglio correlate alla sensazione di disturbo nelle diverse condizioni operative. Si è ottenuta così una sorta di classifica delle macchine in funzione del livello di disturbo provocato. Inoltre, mediante analisi più approfondite sui segnali registrati (in termini di caratteristiche temporali, effetti di modulazione, contenuto in frequenza ecc.) è stato possibile mettere anche in evidenza quali caratteristiche proprie della macchina (principali sorgenti di rumore presenti) e quali condizioni operative (fasi di lavoro, tipologia di materiale) risultino più critiche ai fini delle condizioni di disturbo.
Influenza di condizioni operative e caratteristiche progettuali sulla sound quality di pale caricatrici compatte
Eleonora Carletti;Francesca Pedrielli;
2008
Abstract
Nowadays, the improvement of the noise climate at the operator station of construction machines is a key issue. In fact, the 2003/10/EC Directive on health and safety requirements for noise exposure at work has currently being transposed in all the European Member States, introducing lower noise limits. On the other hand, the market requests are more and more oriented to machines with high-level performances and this trend is making noise one of the key factors for facing the strong competition. In this context, a research project is in progress aiming at characterising the noise climate at the operator station of skid steer loaders during actual working conditions. This paper, in particular, presents some results of a series of binaural measurements carried out at the operator station of three compact loaders, different for dimension and power, with two main goals. Firstly, to investigate in more detail the suitability of the different physical and psycho-acoustic parameters in specifying the "character" of these kinds of noise signals. Then to identify which parameters describe at best the auditory perception of these signals with respect to some desired conditions of comfort. Subjective listening tests performed on these three different compact loaders handling gravel and loam showed that sharpness and loudness are the parameters which correlate best to the subjective perception of annoyance. In addition, the use of a proper metric based on the spectral and temporal analysis of both acoustic (Fig. 4) and psychoacoustic (Fig.3) parameters permitted to deeply investigate which machine characteristics and/or working conditions are more related to the auditory perception. In fact, noise components generated by the hydraulic system and noise components associated with the machine working with gravel turned out to have the greatest impact on the annoyance judgments. This is because they influence both the medium-high frequency range affecting the sharpness values and the loudness variation over time.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
