Sökning: "Sound pressure level"

Visar resultat 11 - 15 av 53 avhandlingar innehållade orden Sound pressure level.

  1. 11. On the Directivity of Railway Noise Sources

    Författare :Xuetao Zhang; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; railway traction noise; railway rolling noise; line source; railway aerodynamic noise; moving source; equivalent source line; De-Dopplerization; sound emission time; sound immission time; directivity; the Doppler factor;

    Sammanfattning : This dissertation deals with the directivity of railway noise. The directivity of railway noise is of particular importance when we have high-rise buildings close to the track, tunnel openings, partial barriers, or when we calculate the maximum sound pressure level during a pass-by based on the sound power level of the different sub-sources of a train. LÄS MER

  3. 12. Sound Generation and Propagation in the Human Upper Airways

    Författare :Lukas Schickhofer; Mihai Mihaescu; Anders Dahlkild; Mats Karlsson; KTH; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Engineering Mechanics; Teknisk mekanik;

    Sammanfattning : The human upper airways embrace the source of phonation and affect the modulation of the voice, which is of vital importance for communication. Moreover, unwanted sounds may be generated in the upper airways due to elastic, collapsible parts that are susceptible to flow-induced vibration and resonance. LÄS MER

  4. 13. Low frequency noise during work. Effects on performance and annoyance

    Författare :Johanna Bengtsson; Göteborgs universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Low frequency noise; performance; workload; annoyance; cortisol; subjective stress; subjective sensitivity to noise; sound characteristics; frequency balance; modulation frequency;

    Sammanfattning : Aims. Low frequency noise (LFN) is defined as "a noise with a dominant frequency content of 20 to 200 Hz". Common sources of LFN in occupational environments are ventilation, heating and air-conditioning systems, computer network installations and compressors. LÄS MER

  5. 14. Investigation of acoustic source characterisation and installation effects for small axial fans

    Författare :Per-Olof Berglund; KTH; []
    Nyckelord :axial fan; airborne sound; source characterisation; transmission path analysis; in-duct. Spherical harmonics;

    Sammanfattning : Fans are often used in equipment such as home appliances andelectronic equipment where the margin of profit is small butcustomers demands on a low noise level are high. Therefore,methods for predicting the noise emitted by an applicationincluding one or several fans are desirable in order toimprove, accelerate and reduce the cost of low-noise design. LÄS MER

  7. 15. On Transient Noise and its Reduction in Hearing Aids

    Författare :Anders Gingsjö; Chalmers tekniska högskola; []
    Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; gun shots; sound exposure; speech intelligibility; signal processing; transient reduction; hearing aid; transient noise;

    Sammanfattning : The most important property of a hearing aid is to facilitate verbal communication for hearing impaired people. However, tuning of the acoustical parameters in a hearing aid in order to optimize the speech intelligibility may result in a harsh and unpleasant sound. LÄS MER