formula
1. Input voltage for speaker
The input voltage needed to drive a speaker can be calculated based on its rated power and impedance. The larger the handling power, the higher the input voltage.
2. Sound wavelength
Assuming at 20 °C(68°F), the speed of sound is roughly 343 m/s. The higher the frequency, the shorter its wavelength.
3. Sound pressure level change with distance
Sound pressure level is often abbreviated as SPL. Assuming far field measurement, the further the distance, the lower the SPL.
4. Sound pressure level change with power
Sound pressure level is often abbreviated as SPL. Assuming the speaker is operating linearly in far field, the higher the power, the higher the SPL.
5. Sound pressure level change with voltage
Sound pressure level is often abbreviated as SPL. Assuming the speaker is operating linearly in far field, the higher the input voltage, the higher the SPL.
6. Microphone sensitivity with different units
Microphone sensitivity states the electrical output compared with acoustic input. Measurement microphone's sensitivty are mostly described in mV/ Pa, whereas common unit of commercial microphone is dB ref 1V/ Pa. The transformation between units is calculated as below
7. Sound volume in different units
The value change will be enormous if sound volume is described in Pa. In electroacoustic field sound volume is often represented in dBSPL. Transform dBSPL back to Pa with the following calculation
8. Output voltage of microphone
The output voltage of microphone can be calculated with the help of test circuit, including DC bias and resistor. Keeping acoustic input the same, the higher the sensitivity, the larger the electrical output.
9. Maximum displacement of speaker
Space must be reserved in front of the speaker considering its possible maximum displacement. Theoretically the maximum can be estimated with the following T/S parameters.
10. System resonant frequency of speaker box
When placed into a closed box, this speaker system resonant frequency (fc) will be higher than that on baffle (fs). Below formula ignores the enclosure resistance.