• On the simultaneous inversion of micro-perforated panels' parameters: application to single and double air-cavity backed systems

      Tayong-Boumda, Rostand; Manyo Manyo, Jacques A.; Siryabe, Emmanuel; Ntamack, Guy E.; University of Bristol; Université de Ngaoundéré; Université du Havre (Acoustical Society of America, 2018-04-20)
      This study deals with the deduction of parameters of Micro-Perforated Panel (MPP) systems from impedance tube data. It is shown that there is an ambiguity problem that exists between the MPP thickness and its open area ratio. This problem makes it difficult to invert the reflection coefficient data fitting and therefore to deduct the MPP parameters. A technique is proposed to reduce this ambiguity by using an equation that links the hole diameter to the open area ratio. Reflection coefficient data obtained for two specimens with different characteristics is employed for searching the MPP parameters using a simulated annealing algorithm. The results obtained demonstrate the effectiveness of this technique.
    • Phonetic and orthographic cues are weighted in speech sound perception by second language speakers: evidence from Greek speakers of English.

      Giannakopoulou, Anastasia; Uther, Maria; Ylinen, Sari; University of Bedfordshire; Winchester University; University of Helsinki (Acoustical Society of America, 2016-05-01)
      Second language (L2) learning can involve processing of speech-sound contrasts that have multiple phonetic cues (e.g. Iverson et al., 2003). This can be particularly difficult for foreign-language learners especially if the cues are weighted differently in the foreign and native languages (e.g., Giannakopoulou et al., 2011, 2013). The orthographic representation of words is suggested to also interfere with speech sound perception in way of presenting additional cues for the second language learner. Greek child and adult speakers of English were studied to determine on what basis they are making perceptual identification between English vowels with the use of pictures as visual stimuli. Performance was impaired for Greek speakers across all tasks but worst for Greek speakers for the picture stimuli task. Findings suggest a 'link' between orthography and perceptual identification serving as an additional cue for L2 speakers.