| 1. |
- Echternach, Matthias, et al.
(författare)
-
Resonatory Properties in Professional Tenors Singing Above the Passaggio
- 2016
-
Ingår i: Acta Acoustica united with Acustica. - 1610-1928 .- 1861-9959. ; 102:2, s. 298-306
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: The question of formant tuning in male professional voices has been a matter of discussion for many years. Material and Methods: In this study four very successful Western classically trained tenors of different repertoire were analysed. They sang a scale on the vowel conditions /a,e,i,o,u/ from the pitch C4 (250 Hz) to A4 (440 Hz) in their stage voice avoiding a register shift to falsetto. Formant frequencies were calculated from inverse filtering of the audio signal and from two-dimensional MRI data. Results: Both estimations showed only for vowel conditions with low first formant (F1) a tuning F1 adjusted to the first harmonic. For other vowel conditions, however, no clear systematic formant tuning was observed. Conclusion: For most vowel conditions the data are not able to support the hypothesis of a systematic formant tuning for professional classically trained tenors.
|
|
| 2. |
- Theuer, Lorenz, et al.
(författare)
-
Micro-electromechanical affinity sensor for the monitoring of glucose in bioprocess media
- 2017
-
Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 18:6
-
Tidskriftsartikel (refereegranskat)abstract
- An affinity-viscometry-based micro-sensor probe for continuous glucose monitoring was investigated with respect to its suitability for bioprocesses. The sensor operates with glucose and dextran competing as binding partner for concanavalin A, while the viscosity of the assay scales with glucose concentration. Changes in viscosity are determined with a micro-electromechanical system (MEMS) in the measurement cavity of the sensor probe. The study aimed to elucidate the interactions between the assay and a typical phosphate buffered bacterial cultivation medium. It turned out that contact with the medium resulted in a significant long-lasting drift of the assay’s viscosity at zero glucose concentration. Adding glucose to the medium lowers the drift by a factor of eight. The cglc values measured off-line with the glucose sensor for monitoring of a bacterial cultivation were similar to the measurements with an enzymatic assay with a difference of less than ±0.15 g·L−1. We propose that lectin agglomeration, the electro-viscous effect, and constitutional changes of concanavalin A due to exchanges of the incorporated metal ions may account for the observed viscosity increase. The study has demonstrated the potential of the MEMS sensor to determine sensitive viscosity changes within very small sample volumes, which could be of interest for various biotechnological applications.
|
|
