Academic literature on the topic 'Supra-aural'

Objetivo Caracterizar a variabilidade teste-reteste com fones supra-aurais e fones de inserção e comparar os limiares auditivos tonais entre os transdutores.Métodos Foram selecionados 74 indivíduos de ambos os gêneros, com limiares auditivos normais e curvas timpanométricas do tipo A. Todos os indivíduos foram submetidos à anamnese, meatoscopia, audiometria tonal por via aérea, ora com o fone supra-aural, ora com o fone de inserção, e logoaudiometria. Após esta primeira avaliação, foi realizada a medida de imitância acústica. Por fim, os procedimentos de audiometria tonal foram repetidos.Resultados O fone supra-aural produziu maior variabilidade teste-reteste, quando comparado com o fone de inserção. Já na comparação dos transdutores, verificou-se, tanto na primeira, quanto na segunda testagem, que as respostas mostraram-se ora semelhantes, ora favorecendo um ou outro transdutor.Conclusão Há maior variabilidade teste-reteste com o fone supra-aural do que com o fone de inserção. No entanto, foram verificados melhores limiares na condição reteste, para ambos os transdutores.

ABSTRACT Purpose: to investigate the prevalence of the ear canal collapse when using supra-aural earphones and to verify if this event is influenced by sex, age, color of the skin and prominent ear. Methods: the collapse was assessed by a visual inspection after the positioning of a detached cushion, pressured against the external ear. Results: a total of 436 individuals, aged 3 to 97 years, participated in the study. Ear canal collapse was observed in 11.4% of the subjects, being mostly bilateral (90.0%). The prevalence ranged from 6.3% to 36.6% across age groups. Males, aged 65 years or above and presence of prominent ear were independently identified as associated factors for the occurrence of ear canal collapse (p<0.05). Despite a higher prevalence for those self-identified as white skinned when compared to non-whites, the difference was not statistically significant. Conclusion: the ear canal collapse, when supra-aural earphones are used, is more likely to occur in men, in elderly people, and among those with prominent ears. The prevalence of the event in this population raises the necessity of a careful examination, previous to any evaluation using supra-aural earphones.

Purpose Low-frequency detection thresholds in quiet vary across transducers. This experiment tested the hypothesis that transducer effects are larger in young children than adults, due to higher levels of self-generated noise in children. Method Listeners were normal-hearing 4.6- to 11.7-year-olds and adults. Warble-tone detection was measured at 125, 250, 500, and 1000 Hz with a sound-field speaker, insert earphones, and supra-aural headphones. Probe microphone recordings measured self-generated noise levels. Results Thresholds were similar across ages for speaker measurements. Transducer effects were larger for children than adults, with mean child–adult threshold differences at 125 Hz of 3.4 dB (insert earphones) and 6.6 dB (supra-aural headphones). Age effects on threshold were broadly consistent with noise levels measured in the ear canal. Conclusions Self-generated noise appears to elevate children's low-frequency thresholds measured with occluding transducers. These effects could be particularly relevant to the diagnosis of minimal and mild hearing loss in children.

Headphone design is facilitated by modelling and has traditionally been carried out using lumped parameters, which are efficient but limited to low frequencies. In this investigation a wave based approach is taken using finite elements to introduce a headphone modelling tool which has the capability to predict high frequency harmonic components in the acoustic field. The development of these increased bandwidth headphone modelling capabilities is carried out over 3 discrete design phases involving 2D axisymmetric and 3D models with the key components being the porous cushion, the headphone driver and the geometric profile of the pinna. The cushion is represented using a well established 6 parameter porous material model as an equivalent fluid which is a convenient approach for a finite element implementation. Characterisation of porous materials using such an approach generally involves an expensive and time consuming measurement regime; this investigation has shown that multi-dimensional optimisation gives an adequate representation without need for this. Simulations using the finite element model headphone model are compared against measurements taken on a HATS mannequin and show good agreement up to 10 kHz, a significant improvement in bandwidth over previous publications. An investigative survey was carried out using these software tools of various headphone dimensional parameters, including a representation of pinna variation which, significantly, shows wide variations in frequency responses at high frequency. If used as an indication of inter-subject variation it suggests the ability to model accurately to a high frequency may only have limited benefits for headphones intended for many different wearers.

This report was written as a part of the Master thesis conducted during the spring of 2017 at Zound Industries International AB and at the Department of Machine Design, School of Industrial Engineering and Management at the Royal Institute of Technology (KTH) in Stockholm. The timeline was 20 weeks of full time work. The purpose of the thesis work was to develop a device to evaluate the acoustical properties of an earphone. This device should be able to accurately simulate the internal volumes and leakages in an earphone. A research question to define the purpose was, “Can the frequency response of a headphone be simulated before manufacturing by using a physical Headphone simulator with variable parameters?”. The method used for the development process, was the so called Double Diamond Model. T he frame of reference presents different acoustic terms, sound measurement equipment and standardized types of earphones. The construction of an earphone is described and the mathematical models used in simulations when developing headphones are presented. The concept development phase of the project was a matter of first formulating requirements in collaboration with the acoustics and design departments. For example, The Headphone simulator should be equivalent to a circum-aural or supra-aural earphone. Then Problem Areas were formulated and explored, this to narrow down the points of interest before developing whole concepts. Concepts were generated, prototyped, regenerated and then evaluated using a Weighted decision matrix. The concept chosen was the Coaxial Concept. In the result chapter the development and manufacturing of the Coaxial Concept is shown. The development was done using first an Alpha prototype to test out the mechanism, then a Beta prototype to prove the concept using the correct materials and manufacturing methods. The Beta prototype was successfully run through some acoustical validations, this to prove that the performance was acceptable. Final improvements were done to the design and a fully CNC machined prototype was ordered. The results were then discussed using an economical, ecological and manufacturing perspective. Here the modularization and larger initial costs were discussed, this to reduce the ecological impact of the Headphone simulator. With the results presented, it was concluded that the Headphone simulator fulfills its purpose. However, further experimental tests are needed to see its full potential. Future work and recommendations are then presented. Here recommendations for drilling leakage paths are presented and the future work is how to improve the mechanical aspects of the Headphone simulator and the potential to develop a smaller version of the Headphone simulator.
Denna rapport skrevs som en del av examensarbetet, för master- och civilingenjörsexamen, som utfördes våren 2017. Projektet utfördes hos Zound Industries International AB och hos Skolan för Industriell Teknik och Management, vid Kungliga Tekniska Högskolan (KTH) i Stockholm, projektet sträckte sig över 20 veckors heltidsarbete. Examensarbetets syfte var att utveckla en hörlursimulator, för att kunna evaluera de akustiska egenskaperna hos en hörlur, under kontrollerade förhållanden. Den här apparaten ska, på ett exakt vis, kunna variera de interna volymerna och läckorna i en hörlur. Det utformades en forskningsfråga som lyder, “Can the frequency response of a headphone be simulated before manufacturing by using a physical Headphone simulator with variable parameters?”. Metoden för utvecklingsprocessen som användes är den så kallade ” Double Diamond Model”. I förundersökningen så presenteras grundläggande akustiska begrepp och mätinstrument. Det definieras vad ljud är och vad som finns i form av testutrustning. I slutet av kapitalet så presenteras de matematiska modeller som används vid akustik simuleringar. Efter förundersökningen formulerades olika krav på hörlursimulatorn och konceptutvecklingen presenteras. Ett av kraven var att hörlursimulatorn ska vara ekvivalent mot en circum-aural eller supra-aural typ av hörlur. Problemområden formulerades och utforskades. Detta gjordes för att på ett mer systematiskt vis, se de mindre områdena av hela hörlurssimulatorn. Efter det utformades koncept, prototyper skapades och koncepten uppdaterades. Sista delen i denna fas var att evaluera koncepten, vilket gjordes med en Weighted decision matrix. Coaxial Concept var det koncept som valdes att arbeta vidare med. I resultatkapitlet är det valda konceptet utvecklat och tillverkat. Framtagningen av konceptet gjordes med hjälp av ett alfa prototyp, för att testa mekanismen. Därefter skapades en beta prototyp i rätt material och tillverkningsmetoder för att bevisa att konceptet fungerar. Beta prototypen testades akustiskt för att verifiera att konceptet fungerade på ett acceptabelt vis. Till sist gjordes några mindre förbättringar och en CNC tillverkad prototyp beställdes. Resultaten diskuteras därefter med hänsyn till ekonomiska, ekologiska och tillverkningsaspekter. En högre första kostnad för ett mer modulärt system skulle kunna bidra positivt till alla dessa tre aspekter. Slutsatsen drogs att hörlursimulatorn uppfyllde sitt syfte men experimentella tester behöver göras för att se om den verkligen är användbar. Det presenterades rekommendationer angående hur läckor ska hanteras när hål ska borras i cylindern. För framtida arbete togs det upp mekaniska förbättringar och potentiellt en mindre variant av hörlursimulatorn skulle kunna tillverkas med samma koncept.

Closed-loop performance of an active noise reduction (ANR) headset is limited by phase lag. Speaker dynamics, control hardware, and acoustic wave propagation from the control speaker to the error microphone all contribute to this phase lag. Understanding these sources of phase lag and their relative effects on performance allows for better design of an analog or digital ANR headset. This thesis demonstrates that the three most significant sources of phase lag in a digital ANR headset are the dynamics of the control speaker's diaphragm, the anti-aliasing filter, and the smoothing filter. Additionally, it is demonstrated that the acoustic wave propagation from the control speaker to the error microphone is not a major contributor of phase lag. Based on these results, it was determined that attention should be focused on the anti-aliasing and smoothing filters when attempting to minimize phase lag and improve a digital ANR system's performance. A design procedure was developed to calculate filter responses that contributed a minimal amount of phase lag to a headset. Using this minimal phase filter design procedure, a digital ANR headset was successfully built and tested. Initial testing revealed that the anti-aliasing filter was not as vital to performance as the smoothing filter. Further testing indicated that the anti-aliasing requirements could be effectively met through the use of only a smoothing filter. Therefore, in order to minimize the phase lag of a digital ANR headset, a smoothing filter may be utilized in the absence of an anti-aliasing filter for some applications.
Master of Science

It is estimated that approximately 360 Million people have a permanent disabling hearing loss (WHO, 2015). The majority of these people live in lower to middle income countries, where screening and follow-up treatment is not always accessible (WHO, 2015). School based hearing screening is one of the procedures that are not always available due to a number of challenges one of which include the high cost of audiometrical headphones. School based hearing screening is performed with an audiometrical headphones and audiometer, it usually can be used to test all school-aged children and adults. In an attempt to reduce the cost of school based hearing screening, this study evaluated the Sennheiser HD 202 II headphone to establish it as a widely available and cost-effective alternative for audiometrical headphones currently used. The headphones were compared to ISO standards (ISO 389-1, ISO 389-5 and ISO 389-9) and IEC standards (IEC 60318-1 and IEC 60645-1). The following characteristics of the headphone were compared: equivalent threshold sound pressure levels, attenuation, maximum permissible ambient noise levels, force of the headband, total harmonic distortion and frequency response. After evaluation the Sennheiser HD 202 II does not show the same standard as audiometrical headphones for diagnostic testing. The headphone can however be used for screening purposes if a few measures are taken into account. The correct ETSPL values should be used, disruptive background noise should be avoided and only the frequencies from the research (250- 1600 Hz) can be tested. once these measures are taken into account the Sennheiser HD 202 II proves to be a cost-effective alternative headphone for screening purposes.
Dissertation (MCommunication Pathology)--University of Pretoria 2016.
Speech-Language Pathology and Audiology
MA
Unrestricted

It is estimated that approximately 360 Million people have a permanent disabling hearing loss (WHO, 2015). The majority of these people live in lower to middle income countries, where screening and follow-up treatment is not always accessible (WHO, 2015). School based hearing screening is one of the procedures that are not always available due to a number of challenges one of which include the high cost of audiometrical headphones. School based hearing screening is performed with an audiometrical headphones and audiometer, it usually can be used to test all school-aged children and adults. In an attempt to reduce the cost of school based hearing screening, this study evaluated the Sennheiser HD 202 II headphone to establish it as a widely available and cost-effective alternative for audiometrical headphones currently used. The headphones were compared to ISO standards (ISO 389-1, ISO 389-5 and ISO 389-9) and IEC standards (IEC 60318-1 and IEC 60645-1). The following characteristics of the headphone were compared: equivalent threshold sound pressure levels, attenuation, maximum permissible ambient noise levels, force of the headband, total harmonic distortion and frequency response. After evaluation the Sennheiser HD 202 II does not show the same standard as audiometrical headphones for diagnostic testing. The headphone can however be used for screening purposes if a few measures are taken into account. The correct ETSPL values should be used, disruptive background noise should be avoided and only the frequencies from the research (250- 1600 Hz) can be tested. once these measures are taken into account the Sennheiser HD 202 II proves to be a cost-effective alternative headphone for screening purposes.
Dissertation (M Communication Pathology)--University of Pretoria, 2017.
Speech-Language Pathology and Audiology
M Communication Pathology
Unrestricted