Octave band SPL Acoustics Experiment shows the SPL in different octaves from, 31.5, 63, 125, 250, 500, 1k, 2k, 4k, 8k and 16k Hz centre frequency. Note that this is not calibrated but only intended to show the principles of octave bands. recording rate rate/2 appended_recording recording_subrange recording_length samples actual_samples/2 actual_samples/2+1 actual_samples+1 actual_samples subrange_start period df time frequency fftX fftY halfFrequency halfFFTtempX halfFFTtempY fft f0 amplitude t a tnow f1 f2 filteredFFT f1x f1y f2x f2y asum FFT31,5 a31,5 asum31,5 FFT63 FFT125 FFT250 FFT500 FFT1K FFT2K FFT4K FFT8K FFT16K a63 a125 a250 a500 a1k a2k a4k a8k a16k asum63 asum125 asum250 asum500 asum1k asum2k asum4k asum8k asum16k Octaves Octave_value tnow recording_subrange recording appended_recording appended_recording recording_length recording_length samples subrange_start subrange_start appended_recording recording_subrange recording_subrange actual_samples actual_samples 1 actual_samples+1 actual_samples 2 actual_samples/2 actual_samples/2 1 actual_samples/2+1 actual_samples rate period 1 period df rate 2 rate/2 0 period actual_samples+1 time 0 rate/2 actual_samples/2+1 frequency recording_subrange fftX fftY 1 actual_samples/2 frequency fftX fftY halfFrequency halfFFTtempX halfFFTtempY halfFFTtempX halfFFTtempY fft fft a fft asum fft halfFrequency f0 f1y tnow a t amplitude fft halfFrequency 22.27 44.54 FFT31,5 FFT31,5 asum31,5 FFT31,5 a31,5 fft halfFrequency 44.54 89.1 FFT63 FFT63 asum63 FFT63 a63 fft halfFrequency 89.1 178.19 FFT125 FFT125 asum125 FFT125 a125 fft halfFrequency 178.19 356.38 FFT250 FFT250 asum250 FFT250 a250 fft halfFrequency 356.38 712.76 FFT500 FFT500 asum500 FFT500 a500 fft halfFrequency 712.76 1425.53 FFT1K FFT1K asum1k FFT1K a1k fft halfFrequency 1425.53 2851.05 FFT2K FFT2K asum2k FFT2K a2k fft halfFrequency 2851.05 5702.11 FFT4K FFT4K asum4k FFT4K a4k fft halfFrequency 5702.11 11404.22 FFT8K FFT8K asum8k FFT8K a8k fft halfFrequency 11404.22 22808.44 FFT16K FFT16K asum16k FFT16K a16k f2 f2 f2x 1 2 3 4 5 6 7 8 9 10 Octaves asum31,5 asum63 asum125 asum250 asum500 asum1k asum2k asum4k asum8k asum16k Octave_value asum31,5 asum63 asum125 asum250 asum500 asum1k asum2k asum4k asum8k asum16k halfFrequency fft Octaves Octave_value asum time recording_subrange t amplitude time recording_subrange