May 9, 2019
The THD peak at ~10 kHz stems mainly from a mode of the MEMS at 21 kHz. When the MEMS is excited with 21kHz it resonates strongly and produces movement and subsequently a higher SPL. Due to small inherent non-linearities in the movement of the MEMS, 10.5 kHz will produce a small frequency component at…
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April 30, 2019
USound specifies and measures Ganymede MEMS speakers, Achelous and Adap, in both acoustic domains: in the Baffle and in the Coupler (artificial ear). For both setups, proprietary measurement adapters are used to fit the standardised setup. In Baffle In the case of the baffle, the measurement adapter places the MEMS speaker with appropriate sealing inside…
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As everyone knows the further away a sound source is, the quieter the sound will be. This is due to the surface expansion of the affected space. One can imagine an ideal point source producing a sound field that moves like an expanding sphere into all 3 dimensions. This means that for doubling the distance…
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The baffle measurement represents a special case of free field measurement. However, in this case, the sound is propagating through the air as a wave. In case of miniature speakers, the transition between mechanical movement and air pressure is poor, that’s why very high excursions are needed to produce high SPL (e.g. very rough example:…
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June 4, 2018
First, we should clarify how power consumption is typically measured with electro-dynamic speakers or BAs. Since the impedance of these speakers is roughly constant over frequency (typically 4, 8 or 32Ω), this impedance value is taken as “nominal”. With this, a very simple transformation from a result obtained with a constant voltage into a result with…
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