1 Introduction
2 ADSR – principle
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Opening the front shutter and closing the side shutters (transition step).
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Exciting the membrane with a purely positive or negative velocity signal and leaving the membrane at an elevated level until the shutter position has been altered (transmission step).
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Closing the front shutter and opening the side shutters (transition step).
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Releasing the membrane back to its equilibrium state which generates a negative or positive sound pulse (opposite to the first one). This pulse is now redirected to the side and damped out (damping step).
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After returning to the equilibrium state, the process can be started again.
3 MEMS-speakers using ADSR – comparison to classical speakers
3.1 MEMS-speakers vs classical speakers
3.2 ADSR vs. analog MEMS-speakers
4 In ear application
4.1 Mechanical model
4.2 Ear canal model
Parameter | Value |
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\(r_{\mathrm{a},5}\) | 50.6 × 106 Pa s m−3 |
\(r_{\mathrm{a},7}\) | 31.1 × 106 Pa s m−3 |
\(m_{\mathrm{a},4}\) | 82.9 kg m−4 |
\(m_{\mathrm{a},5}\) | 9.4 × 104 kg m−4 |
\(m_{\mathrm{a},6}\) | 130.3 kg m−4 |
\(m_{\mathrm{a},7}\) | 983.8 kg m−4 |
\(m_{\mathrm{a},8}\) | 133.4 kg m−4 |
\(c_{\mathrm{a},4}\) | 0.943 × 10−12 m5 N−1 |
\(c_{\mathrm{a},5}\) | 1.9 × 10−12 m5 N−1 |
\(c_{\mathrm{a},6}\) | 1.479 × 10−12 m5 N−1 |
\(c_{\mathrm{a},7}\) | 2.1 × 10−12 m5 N−1 |
\(c_{\mathrm{a},8}\) | 1.517 × 10−12 m5 N−1 |