In Sweden, about 10% of the adult population experienceshearing problems that cause them difficulties in everydaycommunication, and approximately 60 000 people are providedwith hearing aids each year. Despite the fact that modernhearing aids can facilitate speech communication in a widerange of listening environments, many hearing-aid users aredissatisfied with their hearing aids. It is likely that theclinical methods used for individual fitting of the hearingaids are not optimal. The current study investigates prescriptive methods fornonlinear, wide dynamic range compression (WDRC) hearinginstruments. The goal is to draw general conclusions about thepreferences of hearing aid users. Therefore, the prescriptionsare evaluated using well-established models of loudness andspeech intelligibility. Current methods differed considerably in prescribed gain.Evaluations in a laboratory test, with 20 hearing-impairedlisteners, showed that these differences led to largedifferences in perceived and calculated loudness, but only tominor differences in measured and predicted speech recognitionscores. The difference in loudness was explored in a studywhere 21 first-time hearing-aid users compared twoprescriptions. One method led to normal and the other toless-than-normal overall calculated loudness (according to theloudness model of Moore and Glasberg (1997)). The prescriptionthat led to less-than-normal overall loudness was clearlypreferred in field and in laboratory tests. Preferred overall loudness was then quantified.Hearing-impaired participants with mild to moderate hearingloss preferred considerably less-than-normal overall calculatedloudness in both eld and laboratory tests. There were nosignificant differences between inexperienced and experiencedhearing aid users. Normal-hearing participants, on the otherhand, preferred close-to-normal overall calculated loudness. Inaddition, a potential problem with the loudness model wasencountered: despite the fact that the hearing-impairedlisteners were provided with less than normal overallcalculated loudness, they rated loudness higher than thenormal-hearing listeners. The results refute the most commonly adopted rationale forprescriptive methods for WDRC hearing aids - that overallloudness should be restored to normal. Hearing-impairedlisteners with mild to moderate hearing loss preferredconsiderably less than normal overall loudness. This should betaken into account when deriving new prescriptive methods, andwhen providing clients with hearing aids. Key words:hearing impairment, hearing aid, nonlinear,WDRC, hearing aid experience, prescription, loudness, loudnessmodel, speech intelligibility, preference.

<p>In Sweden, about 10% of the adult population experienceshearing problems that cause them difficulties in everydaycommunication, and approximately 60 000 people are providedwith hearing aids each year. Despite the fact that modernhearing aids can facilitate speech communication in a widerange of listening environments, many hearing-aid users aredissatisfied with their hearing aids. It is likely that theclinical methods used for individual fitting of the hearingaids are not optimal.</p><p>The current study investigates prescriptive methods fornonlinear, wide dynamic range compression (WDRC) hearinginstruments. The goal is to draw general conclusions about thepreferences of hearing aid users. Therefore, the prescriptionsare evaluated using well-established models of loudness andspeech intelligibility.</p><p>Current methods differed considerably in prescribed gain.Evaluations in a laboratory test, with 20 hearing-impairedlisteners, showed that these differences led to largedifferences in perceived and calculated loudness, but only tominor differences in measured and predicted speech recognitionscores. The difference in loudness was explored in a studywhere 21 first-time hearing-aid users compared twoprescriptions. One method led to normal and the other toless-than-normal overall calculated loudness (according to theloudness model of Moore and Glasberg (1997)). The prescriptionthat led to less-than-normal overall loudness was clearlypreferred in field and in laboratory tests.</p><p>Preferred overall loudness was then quantified.Hearing-impaired participants with mild to moderate hearingloss preferred considerably less-than-normal overall calculatedloudness in both eld and laboratory tests. There were nosignificant differences between inexperienced and experiencedhearing aid users. Normal-hearing participants, on the otherhand, preferred close-to-normal overall calculated loudness. Inaddition, a potential problem with the loudness model wasencountered: despite the fact that the hearing-impairedlisteners were provided with less than normal overallcalculated loudness, they rated loudness higher than thenormal-hearing listeners.</p><p>The results refute the most commonly adopted rationale forprescriptive methods for WDRC hearing aids - that overallloudness should be restored to normal. Hearing-impairedlisteners with mild to moderate hearing loss preferredconsiderably less than normal overall loudness. This should betaken into account when deriving new prescriptive methods, andwhen providing clients with hearing aids.</p><p><b>Key words:</b>hearing impairment, hearing aid, nonlinear,WDRC, hearing aid experience, prescription, loudness, loudnessmodel, speech intelligibility, preference.</p>

Lors d’une conversation téléphonique entre deux personnes, le niveau sonore perçu (i.e. la sonie) doit être réglé pour être confortable à l’écoute. Depuis plus de trente ans, nous utilisons un indicateur appelé « loudness Rating (LR) » pour régler la sonie dans cette zone de confort. Cet indicateur a été développé pour la téléphonie filaire classique. Cependant, avec les avancées récentes en télécommunication, l’utilisation actuelle du LR montre certaines limitations. Ainsi, le but de cette thèse est d’étudier la possibilité de remplacer l’indicateur LR par un modèle de sonie plus sophistiqué issu de l’état de l’art, basé sur le modèle de Zwicker. Nous avons sélectionné puis évalué le comportement des quatre modèles de sonie les plus répandus. Dans ce but, nous avons conçu une nouvelle méthode de mesure de sonie appelée : « Mesure Indirecte du Niveau d’Isosonie (MINI) ». La conclusion de cette évaluation est que ces modèles de sonie peuvent être utilisés pour remplacer le LR en mode mains-libres. Cependant, leur utilisation en mode combiné nécessite des études complémentaires afin d’améliorer leurs prédictions. / During a telephone conversation between two people, the perceived sound level (i.e. loudness) must be comfortable for the listening. For over thirty years, we have been using a measure called « Loudness Rating (LR) » to adjust the loudness in this comfort zone. This indicator was developed for the landline telephony. However, with recent advances in telecommunications, the current use of LR exhibits some limitations. Thus, the aim of this PhD thesis is to study the possibility of replacing the LR indicator by a more sophisticated state-of-art loudness model based on Zwicker’s model. We selected and evaluated the behavior of the four most common loudness models. For that purpose, we designed a new method of loudness assessment called « Mesure Indirecte du Niveau d’Isosonie (MINI) ». The conclusion of this evaluation is that these loudness models can be used to replace the LR in hands-free mode. However, their use in handset mode requires additional studies to improve their predictions.