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.

Loudness growth evaluation is important to comprehend the theoretical implication of loudness in both normal hearing and hearing impaired people, as well as applied applications in hearing-aid design. However, current psychoacoustic procedures are subjective, time consuming and require the constant attention of participants. The primary aim of the present study is to investigate the feasibility of objectively assessing the loudness growth function by using the Auditory Brainstem Response (ABR). Previous studies applied either non-frequency specific click stimuli or tone burst stimuli to evoke auditory brainstem responses. Although the advantage of a chirp stimulus in producing a more reliable response has been well documented in many studies, no one has previously used this stimulus to evaluate loudness growth functions. One octave-band chirp stimuli with center frequencies of 1000 Hz and 4000 Hz were chosen to evoke ABRs at 7 different stimulus intensities from 20 dB nHL to 80 dB nHL with 10 dB steps. In the psychoacoustic procedure, subjects were asked to rate the perceived loudness of each presented stimulus. The recorded ABR trials were averaged by a modified version of weighted averaging based on Bayesian inference. This method of averaging decreases the effects of non-stationary noise sources by calculating a number of locally-stationary noise sources based on a series of F-tests. The peak-to-trough amplitude of the most salient peak of the ABR at each intensity constituted the physiological loudness estimate. Linear and power functions relating the psychoacoustical results and the ABR measurements were compared. The obtained results were in good agreement with equal-loudness contours and estimated loudness from the loudness model for time-varying sounds of Glasberg, & Moore (2002). We concluded that loudness growth can be estimated with ABRs to frequency-specific chirp stimuli. / Thesis / Master of Science (MSc)

The aim of the study was to investigate whether South African free to air television and radio broadcast audio contains loudness fluctuations that fall outside previously determined limits of listener comfort. This is a relevant aim as consumers often complain about loudness fluctuations in broadcast audio (e.g. “why are the commercials so loud?”). Loudness is an inherently subjective phenomenon that is not only subject to differences in human perception from day to day, but also more specifically by the frequency content, localisation, spatialisation and duration of the audio stimulus. Traditional audio level meters only measure the audio signal or digital samples, and do not take any of these psychoacoustic phenomena into consideration. Broadcast audio has traditionally been regulated by specifying the permitted maximum level (PML) of the signal to avoid overloading the transmitter or over- modulation the broadcast signals. While this is necessary to keep the transmission inside the technical dynamic range of the medium, it does not correspond to the perceived loudness of these signals. With the addition of power dynamic range processing techniques, content producers and broadcasters were now able to raise the average level (and correspondingly the perceived loudness) without affecting the permitted maximum level or the peak level of the signal. Broadcasts were still compliant, but subjectively louder. As this process has not been done uniformly across various stations, and various types of audio, fluctuations occur both between stations, and between different segments on the same station. These fluctuations are the cause of listener complaints. There has been a move in international regulators and broadcasters to make a paradigm shift from peak normalisation to loudness normalisation of broadcast audio content. Limited, to no adoption, of this new paradigm in South African broadcasting is evident. This study provides baseline data of the status quo of South African free to air broadcast audio to investigate whether it contains problematic fluctuations, and therefore whether a move from peak to loudness normalisation could possibly have a positive effect. The study found that generally radio broadcasts suffered from greater and more problematic loudness fluctuations compared to television. Televisions broadcasts differed enough from station to station to cause inter-station loudness fluctuations outside previously determined limits for listener comfort, but not intra-station fluctuations. SABC 2 was found to be the loudest and SABC 3 the softest at this particular testing high-site. Radio broadcasts contained a large proportion of inter-station fluctuations, and while it varied considerably from station to station, each station contains some proportion of intra-station fluctuations. Advertisements were found not to be the loudness programme segment type. It was found that the following segments types were generally the softest to the loudest: talking, advertisements, links (interstitials) and music. Ikwekwezi FM was found to be the loudest station by far, with Lotus FM the softest, with a very wide difference of 13.7LU between their integrated station loudness values. The vast majority of broadcast audio was found to have a loudness range appropriate to the intended platform, but perhaps limited to the range appropriate the lowest common denominator, resulting in signals with high to extreme levels of dynamic compression and peak limiting. The study also provided much greater levels of detail of the nature and extent of all loudness fluctuations, especially for radio loudness data. Additionally, ‘zap testing’ methodology was tested to simulate real-life inter-station fluctuation scenarios, and also found to be an efficient method for extrapolating overall station loudness for a larger set of stations. Finally, the study recommends the paradigm shift from peak to loudness normalisation for all audio content producers and distributors in the country, and suggests the EBU R 128 recommendation as the most viable starting point. / Mini Dissertation (MMus)--University of Pretoria, 2016. / Music / Unrestricted

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Loudness is a subjective measure of how loud an audio signal is perceived. Due to commercial pressures loudness has been exploited in broadcasts to attract and reach viewers and listeners. By means of signal processing it is possible to increase the loudness of an audio signal and still meet the contemporary legislated signal levelling requirements. With an aspiration to achieve equal average loudness between all broadcasting programmes the European Broadcasting Union have issued a standard that proposes methods to quantify loudness. This thesis applies those loudness quantities and proposes an online algorithm that adaptively normalises the loudness of audiovisual broadcasts without affecting the dynamics within programmes. The main application of the algorithm is to normalise the audio in broadcasting and distributing equipment with real-time requirements. The results were derived from simulations in Matlab using commercial broadcasts. The results showed that for certain types of broadcasts the algorithm managed to reduce the variation in average programme loudness with minor effects on dynamics within programmes. / Loudness är ett subjektivt mått på hur högljudd en ljudsignal uppfattas. Till följd av kommersiellt tryck har loudness utnyttjats i sändningar för att locka och nå tittare. Genom signalbehandling är det möjligt att öka loudness-nivån på en ljudsignal och fortfarande uppfylla dagens lagstadgade signalnivåkrav. Med strävan att uppnå en lika medel-loudness-nivå mellan alla program har Europeiska radio- och TV-unionen publicerat en standard som föreslår metoder för att kvantifiera loudness. Denna rapport tillämpar dessa metoder och föreslår en algoritm som adaptivt normaliserar loudness-nivån i audiovisuella sändningar utan att påverka dynamiken inuti program. Huvudtillämpningen för algoritmen är att normalisera ljudsignalen i sändnings- och distributionsutrustning med realtidskrav. Resultaten erhölls från simuleringar i Matlab där kommersiella sändningar användes. Resultaten visade att för vissa typer av sändningar lyckades algoritmen minska variationen i medel-loudness-nivå med smärre påverkan på dynamik inuti program.

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Thesis (Ph.D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xiii, 180 p.; also includes graphics. Includes bibliographical references (p. 169-172). Available online via OhioLINK's ETD Center

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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.