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Applied Acoustics test - 04/12/2015
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Matricola123456
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1) Compute the lenght in samples of the convolution of an anechoic signal of 30+F s with an impulse response of 2+E/10 s, at 48 kHz
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Length =1847999samples
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2) A digital filter should emulate the reverb of a church, several second long. Which filtering technique provides less CPU load?
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o FIR filtering in time domain
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o Overlap-Save filtering in frequency domain
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o Equally-Partitioned convolution
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o Not-Equally-Partitioned convolution
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o IIR filtering
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3) A digital filter should emulate the reverb of a church, several second long. Which filtering technique provides less latency?
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o FIR filtering in time domain
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o Overlap-Save filtering in frequency domain
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o Equally-Partitioned convolution
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o Not-Equally-Partitioned convolution
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o IIR filtering
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4) In a standing wave tube, the ratio between maximum and minimum pressures is 5+F. Compute the sound absorption coefficent α of the sample according to ISO 10534.
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write number and measurement unit (with a space in between and no other spaces)
Alfa =0.3055555556
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5) In a standing wave tube, the ratio I/EDc is equal to 0.2+E/20. Compute the sound absorption coefficent α of the sample with the Sound Intensity method.
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write number and measurement unit (with a space in between and no other spaces)
Alfa =0.6206896552
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6) An EN-1793-5 measurement is performed at 0° incidence angle with dsm=1+F/20 m and dm=0.2+E/100 m. The incident sound impulse has an SPL=90+F dB,
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and the absorption coefficient of the barrier is 0.3+D/20. Compute the SPL of reflected sound impulse.
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write number and measurement unit (with a space in between and no other spaces)
SPL,ref = SPL,inc + 20*log10(dsm/(dsm+2*dm)) + 10*log10(1-Alfa) =
90.16311699dB
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7) Inside a reverberant room having V=250 m3 the value of T1 and T2, measured before and after inserting 10 m2 of absorbing material, are respectively 4+F/10 and 2+E/10 s.
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Compute the absorption coefficient of the absorbing material.
Alfa =0.7304347826
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