TY - JOUR
T1 - Random changes in envelope of AM tones and their detection
AU - Ozimek, Edward
AU - Konieczny, Jacek
AU - Suzuki, Yoiti
AU - Sone, Toshio
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1998
Y1 - 1998
N2 - The aim of this investigation was to determine the detection thresholds of sinusoidal and random changes in envelope of amplitude modulated (AM) signals. The envelope changes were obtained as a result of modulation of a pure-tone carrier by chosen types of modulators, which gave either sinusoidal, pseudorandom, or random (Gaussian) amplitude modulation. For pseudorandom and random modulation, the detection thresholds were determined when only modulation depth (m) of AM signals was changed randomly (fm const) or when both modulation depth and modulation frequency (fm) were changed randomly (fm random). The data showed that for low modulation frequency (fm≤64 Hz) the detection thresholds for sinusoidal amplitude modulation (SAM), pseudorandom amplitude modulation (PAM) and random amplitude modulation (RAM) overlapped one another in the limit of the standard deviation (SD). However, for higher modulation frequencies, the average threshold for the RAM (fm const) was about 3 dB lower (around fm=128 Hz) than that for sinusoidal amplitude modulation. In this case the PAM threshold was similar, within the limit of SD, to the SAM threshold. However, when random changes in amplitude were combined with random changes in frequency, the PAM (fm random), and RAM (fm random) thresholds decreased about 5 dB relative to the SAM threshold.
AB - The aim of this investigation was to determine the detection thresholds of sinusoidal and random changes in envelope of amplitude modulated (AM) signals. The envelope changes were obtained as a result of modulation of a pure-tone carrier by chosen types of modulators, which gave either sinusoidal, pseudorandom, or random (Gaussian) amplitude modulation. For pseudorandom and random modulation, the detection thresholds were determined when only modulation depth (m) of AM signals was changed randomly (fm const) or when both modulation depth and modulation frequency (fm) were changed randomly (fm random). The data showed that for low modulation frequency (fm≤64 Hz) the detection thresholds for sinusoidal amplitude modulation (SAM), pseudorandom amplitude modulation (PAM) and random amplitude modulation (RAM) overlapped one another in the limit of the standard deviation (SD). However, for higher modulation frequencies, the average threshold for the RAM (fm const) was about 3 dB lower (around fm=128 Hz) than that for sinusoidal amplitude modulation. In this case the PAM threshold was similar, within the limit of SD, to the SAM threshold. However, when random changes in amplitude were combined with random changes in frequency, the PAM (fm random), and RAM (fm random) thresholds decreased about 5 dB relative to the SAM threshold.
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U2 - 10.1250/ast.19.83
DO - 10.1250/ast.19.83
M3 - Article
AN - SCOPUS:0032025738
SN - 1346-3969
VL - 19
SP - 83
EP - 94
JO - Journal of the Acoustical Society of Japan (E) (English translation of Nippon Onkyo Gakkaishi)
JF - Journal of the Acoustical Society of Japan (E) (English translation of Nippon Onkyo Gakkaishi)
IS - 2
ER -