Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Sound power describes the emission of sound from sound sources. Despite today's state-of-the art measurement techniques, the current sound power determination methods are restricted due to various limitations. To overcome these limitations, a new sound power determination method is proposed, aiming at the establishment of traceability in airborne sound. This will enable the characterization of a sound source by its free field sound power. The dissertation describes a study on the dissemination process, which will allow the sound power of a device under test located at a real surrounding environment, to be referred to its free field sound power. Apart from the sound power, the corresponding uncertainty may be estimated in a transparent way, where each uncertainty component is provided. The basic tool for the dissemination process is the substitution method using aerodynamic reference sound sources, applied to both sound pressure and sound intensity measurements. Initially, a theoretical investigation deals with the factors that influence the substitution method. Experimental results are then presented based on measurements using a specially designed scanning apparatus. The transition from calibration to in situ conditions and the required correction, due to changes in environmental and operational conditions, is then discussed. In the last section, the sound power level of devices under test is determined along with its related uncertainty, which is further compared to the up-to-date uncertainty values.

Engineering --- Acoustics. --- Construction --- Industrial arts --- Technology --- sound power --- substitution --- correction --- uncertainty --- traceability

Choose an application

• Reference Manager
• EndNote
• RefWorks (Direct export to RefWorks)

Listeners with hearing impairments have difficulties understanding speech in the presence of background noise. Although prosthetic devices such as hearing aids and cochlear implants may improve the hearing capability, listeners with hearing impairments still complain about their speech perception in the presence of noise. The basic tonal audiometry only gives a cursory idea of the degree of difficulty in spoken communication caused by hearing loss because it does not assess the ability to understand speech. Therefore, the use of speech-in-noise tests to measure hearing loss in complex scenes is an integral part of a patient's audiological study. Most research has concentrated on studying only stationary sound sources, but in natural acoustic scenes, conversations may become very difficult to understand in the presence of moving sound sources such as a moving talker or a passing vehicle. Therefore, this thesis deals with quantifying speech perception in the presence of moving maskers through virtual sound sources presented binaurally via headphones. Significant differences in several conditions were found, revealing that the auditory system assesses differently the moving maskers than the stationary maskers. Therefore, the inclusion of moving conditions in clinical listening tests is recommended, in order to assess speech-in-noise perception in a more realistic environment.

Engineering --- speech-in-noise perception --- binaural technology --- room acoustics --- moving sound sources --- head movements --- Acoustics.