Sometimes audio signals are rough problems to analyze. Who knew that it was a parameter of acoustic roughness? Well there is and it's called the asper.
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acoustic roughness is measured in aspers. an asper is the roughness of a 1 khz tone, at 60 db, 100% modulated at 70 hz. that is, the signal
(1 + sin(140π t )) sin(2000π t )
where t is time in seconds.
here’s what that sounds like (if you play this at 60 db, about the loudness of a typical conversation at one meter):
and here’s the python code that made the file:
from scipy.io.wavfile import write from numpy import arange, pi, sin, int16 def f(t, f_c, f_m): # t = time # f_c = carrier frequency # f_m = modulation frequency return (1 + sin(2*pi*f_m*t))*sin(2*f_c*pi*t) def to_integer(signal): # take samples in [-1, 1] and scale to 16-bit integers, # values between -2^15 and 2^15 - 1. return int16(signal*(2**15 - 1)) n = 48000 # samples per second x = arange(3*n) # three seconds of audio # 1 asper corresponds to a 1 khz tone, 100% modulated at 70 hz, at 60 db data = f(x/n, 1000, 70) write("one_asper.wav", n, to_integer(data))
Published at DZone with permission of John Cook. See the original article here.
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